Symposium D
Advances in Inorganic Luminescent Materials and Applications

ABSTRACTS

Session D-1 - Physics and Modelling of Luminescent Materials

D-1:IL02  Valence Stability of Rare Earth Ions by Madelung Lattice Site Potential in Various Oxide Lattices
M. YOSHIMURA, National Cheng Kung University, Promotion Center for Global Materials Research, Tainan, Taiwan, Formerly, Tokyo Institute of Technology, Japan

The valence stability of allio-valent ions in various oxides with different crystal structures is an important factor to control the essential properties of those oxides: For example, rare earth ions like Eu in phosphors, Ce ions in phosphors and catalysts, 3d ions in magnetic materials, Cu ions in superconductors, etc. Although lots of studies have been reported on the relation between the properties and the valence of ions in various crystal lattices: perovskites, spinels, garnets, sheelites, etc., the most important general concept for the valence stability of such ions have little been reported even now. The present study demonstrates that the valence stability of certain ions in particular lattices is directly related to the Madelung self-site potential(Φ) of the lattice site where the ions are located in the crystal lattice. The ф ranges -1.359 ~ -1.380 [Å-1] for Eu2+, -2.038 ~ -2.107 for Eu3+, -1.908 ~ -2.103 for Ce3+ and -2.710 ~ -2.797 for Ce4+, respectively. According to the most fundamental ionic model, the total Madelung lattice energy (U) can be expressed by the equation: Since the ionization potential [loss] can be compensated by high lattice site potential [gain], high valence ion can be stabilized in a lattice site with high lattice-site potential.


D-1:IL03  Discovery of Novel Narrow-band Red Phosphors using High-throughput First Principles Descriptors
ZHENBIN WANG, SHYUE PING ONG, Department of NanoEngineering, University of California San Diego, La Jolla, CA, USA

As a red component, nitride phosphors are widely used in achieving warm-light-emitting diodes (LEDs) with high color rendition. There is therefore a huge impetus for the development of new nitride phosphors to further improve the luminous efficacy and color rendition of phosphor-converted LEDs. However, the harsh synthesis conditions (high temperature and/or high pressure) of nitride phosphors have severely hindered this development. In this talk, we outline a computationally efficient multi-property screening framework for identifying promising narrow-band red-emitting phosphors utilizing the Eu2+ activator based on first principles calculations. This screening relies on the use of first principles descriptors that correlate with desired red phosphor properties, such as high thermal/chemical stability, high quantum efficiency, near-UV absorption wavelength and narrow red emission band. We will demonstrate the applicability of our approach through its ability to identify existing well-known narrow-band red phosphors. Finally, we will propose several promising novel red phosphor host materials using this approach. Our study presents a highly efficient way to discover and design novel phosphors for illumination-grade lighting.
 

D-1:IL04  Luminescence of Organo-metal-halide Perovskites Probed at Micro- and Nanoscales
I.G. SCHEBLYKIN, Chemical Physics, Lund University, Lund, Sweden

Organo-metal halide perovskites (OMHPs) attract lots of attention as promising solution-processable semiconductors for solar energy conversion, electroluminescence and lasing. Despite of the great progress in devices, fundamental questions including the nature of photoluminescence (PL) and mechanisms of charge recombination and far from been understood. I will talk about several phenomena we observed by PL spectroscopy with high spatial resolution. We employed luminescence microscopy, super-resolution optical imaging, PL spectroscopy and electron microscopy for the very same sample in order to correlate the sample morphology and properties. We found a huge spatial inhomogeneity of the PL intensity and lifetime at the scales from nanometers and above and assigned it to a vast distribution of the PL quenching trap concentration. The trap concentration can be changed by light irradiation which can lead to several orders of magnitude increase of the PL yield. For crystals of less than one micrometer in size we observed PL blinking which shows that a single photoconvertible trap can control PL of the whole crystal. Super-resolution PL microscopy demonstrated so-called emitting sites – small areas (ca 100 nm) having orders of magnitude higher PL yield than the rest of the material.

 
Session D-2 -  Photonic and Biophotonic Structures; Plasmonic Metamaterials; Photovoltaics; Non-linear Optical Materials and Processes

D-2:IL03  Contact-free Terahertz Thermometry in Solid, Liquid and Biological Model Systems
R. NACCACHE, Dept. of Chemistry and Biochemistry, Concordia University,   Montréal, Canada; A. MAZHOROVA, A. MARKOV, L. RAZZARI, F. VETRONE, R. MORANDOTTI, Institut National de la Recherche Scientifique – Énergie, Matériaux et Télécommunications, Université du Québec, Varennes, QC, Canada; M. CLERICI, School of Engineering, University of Glasgow, Glasgow, UK; L.K. KHORASHAD, A.O. GOVOROV, Dept. of Physics and Astronomy, Clippinger Research Labs, Ohio University, OH, USA

Recently, nanomaterials have garnered significant attention in the effort to develop novel nanoparticle-based probes than can be used in imaging and therapeutics. Of particular interest are gold nanoparticles, which following resonant excitation with light, show a surface plasmon resonance effect and a transfer of energy to the environment in the form of heat. We have used gold nanoparticles in combination with terahertz radiation to develop a contact-free approach for heating, temperature sensing and imaging. More specifically, we exploit the change in the refractive index of water, induced by localized NIR heating of plasmonic nanostructures. We observe a linear relationship correlating change in the reflected terahertz amplitude and area under the curve as a function of increasing temperature. This was translated to a thermometric relationship allowing for temperature sensing following an induced heat stimulus. We extended our results to the porcine skin model system in order to mimic photothermal heating and demonstrated the capacity to sense the temperature and map its distribution in the localized injection site, following controlled NIR plasmonic heating. As a result, we have developed a terahertz biological thermometer, or a “teramometer”.


D-2:IL04  Glass-derived Photonic Crystals structures
A. CHIAPPINI1, C. ARMELLINI1, A. PIOTROWSKA1,2, A. CARPENTIERO1, S. VARAS1, M. MAZZOLA1, L. PASQUARDINI3, L. LUNELLI3,4, A. VACCARI5, S. PELLI6,7, A. LUKOWIAK8, A. QUANDT9, C. PEDERZOLLI3, D. ZONTA1,2, G.C. RIGHINI6,7, R. RAMPONI10, M. FERRARI1,7, 1CNR-IFN CSMFO Lab., Povo, Trento, Italy, 2Dep. of Civil, Environmental and Mechanical Engineering, Univ. of Trento, Trento, Italy, 3FBK-LaBSSAH, Povo Trento, Italy, 4CNR-Institute of Biophysics, Unit at Trento, Povo Trento, Italy, 5ARES unit at FBK-CMM, Povo, Trento, Italy, 6IFAC-CNR, MiPLab., Sesto Fiorentino, Italy, 7Enrico Fermi Centre, Roma, Italy, 8Institute of Low Temperature and Structure Research, PAS, Wroclaw, Poland, 9MERG Group, University of Witwatersrand, Johannesburg, South Africa, 10IFN-CNR and Politecnico di Milano, Dip. di Fisica, Milano, Italy

Photonic crystals (PhCs) influence the propagation of light by their periodic variation in dielectric contrast or refractive index. Colloidal self-assembly of dielectric spheres is one of the most favoured and low cost methods for the formation of PhCs as artificial opals. These systems are constituted by colloidal spheres assembled in a periodic structure and the spatially ordered variation of the dielectric function gives rise to photonic bands whose optical features can be suitably tailored playing with the dimension and the nature of the colloids. In this presentation, we give an overview on the main techniques developed to fabricate opal structures and, particularly, we highlight the advantages of a co-assembly deposition, respect to the traditional two steps approach, for fabricating high quality inverse structures. Starting from these structures, we discuss the recent results obtained by our team in tailoring the photoluminescence emission of Cy3 activated opals (which find promising application in the fluorescence-based biosensors field), in developing metallo-dielectric colloidal systems for SERS substrates and in fabricating low-cost responsive chromatic structures sensitive to chemical and physical stimuli.


D-2:L05  Cell Performances of Inorganic-organic Hybrid Solar Cells using Fluorosilicate/Phosphorus Oxide Composite Microparticles
KEISUKE SATO, Y. SUGANO, K. HIRAKURI, Department of Electrical and Electronic Engineering, Tokyo Denki University, Adachi-ku, Tokyo, Japan; N. FUKATA, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki, Japan

Development of inorganic-organic hybrid solar cells consisting of semiconductor microparticles and organic polymers have been proceeding rapidly in recent years. However, the inorganic microparticles are confronting some problems, such as complicated preparation technique and high-cost production. Therefore, it is necessary to develop new synthesis approaches for realization of their facile and low-cost productions. In this presentation, we propose a new way to fabricate novel microparticles consisting of fluorosilicate/phosphorus oxide composites by simplified procedures based on a chemical approach. Moreover, we also discuss the cell performances of the inorganic-organic hybrid solar cells using such composite microparticles. The composite microparticles with mean diameter of less than 2 μm were densely formed on micro-textured Si substrate by using the simplified and cheap synthesis system in which only silicon/phosphorus powders and nitric hydrofluoric acid solution were hermetically sealed in polymeric container without any vacuum systems. The hybrid solar cells using such composite microparticles showed a power conversion efficiency of 4.06%. Our suggested synthesis technologies can provide a new chemical route for the facile and low-cost productions of hybrid solar cells.


Session D-3 - Phosphors, Quantum Dots and Low Dimensional Materials for Lighting and Displays

D-3:L02  Tunable Performance of Nanostructured Eu-doped Oxide and Oxynitride Thin Films
I. CAMPS, A. MARISCAL, R. SERNA, Laser Processing Group, Institute of Optics - CSIC, Madrid, Spain

Rare earth (RE) doped materials are ideal candidates for the development of reliable emitters for integrated lighting devices. Silicon oxynitrides are compatible with the current silicon technology and show excellent optical properties including high transparency in the VIS-IR, and a tunable refractive index from that of SiO2 (1.45) to that of Si3N4 (2.01). Moreover, the inclusion of Al2O3 (1.67) to form SiAlON is advantageous providing further tuning of the optical properties and decreases the maximum phonon energy, which enhances RE-light emission efficiency. Some RE doped SiAlON have been studied as phosphors, however it have been seldom produced as thin films. We report the optical properties and emission performance of both a-Al2O3 and SiAlON thin films with nanostructured Eu doping. The Eu is distributed in the films forming well-defined doping layers with different interlayer spacing. It will be demonstrated that this nanometric distribution is essential to obtain either the 2+ or 3+ Eu oxidation state. Therefore, the film emission could be tuned from a broadband white emission characteristic from the superposition of the 5d levels to the 4f levels of the Eu2+, to a narrow and well-defined emission peaks characteristic of the 4f-4f transitions of the Eu3+.


D-3:L03  Phosphor in Glass Based on High Refractive Index Glasses for LEDs
V. ASEEV, Y. TUZOVA, Y. NEKRASOVA, N. NIKONOROV, E. KOLOBKOVA, Y. FEDOROV, ITMO University, St. Petersburg, Russia

White light-emitting diodes (LEDs) have promising features such as low energy consumption, long lifetime, small size, fast switching, as mercury free nonpolluting environment. For fixing powered phosphor on a chip, silicone resins are generally used. However these materials are unstable to UV exposure and temperatures above 150 °C. One of the perspective matrixes for fixing commercial powered phosphor is phosphor in-glass (PiG). It is a simple mixture of typical commercial phosphor and glass powders (or frits). During heat treatment glass powders can be formed into a stable matrix for the phosphors through the viscous sintering process. Phosphors as a mixture of crystalline powder of Y3Al5O12:Ce3+ and lead germanate high-refractive glasses have been studied in this paper. Refractive index and size of the crystals was varied to reduce scattering at the interface between the crystal powder and the glass. Spectral and luminescent properties of Y3Al5O12:Ce3+ in PiG have been investigated. It has been shown that the temperature quenching of the luminescence in the PiG less than one in the silicone resins (up to 10%). The highest value of the luminous efficacy was ~60 lm/W, which is comparable to that of commercial white LEDs.


D-3:L04  Ln(III)-Doped ZrO2 Nanoparticles through Hierarchical Multilayer Growth Strategy for White Light Emission Applications
C.S. OLIVEIRA, F.A. SIGOLI, I.O. MAZALI, Institute of Chemistry, University of Campinas - UNICAMP, Campinas, SP, Brazil

Light-emitting lanthanide(III)-doped ZrO2 doped is a recent focus of study for solid state lighting applications due to the combination of lanthanide(III) narrow emission bands with the properties of ZrO2, such as high thermal and chemical stabilities, large band gap, low phonon energy, low thermal conductivity and low toxicity. A mesoporous silica host containing a ZnO covering layer was used as host to prepare and prevent nanoparticles coalescence. Hierarchically nanostructured Ln(III)-doped ZrO2 nanoparticles (Ln = Eu and Tb) with controlled particle sizes (4-5 nm) and tetragonal crystalline structure were prepared by layer-by-layer growth method named Impregnation-Decomposition Cycles (IDC). The ZnO layer covering the silica surface contributed significantly to reduction of non-radiative decay rate of O-H oscillators improving the Ln(III) emission intensities. Excitation spectra and lifetime results show no energy transfer from Tb(III) to Eu(III) ions. Emission spectra (lambdaexc = 260 nm) of Tb(III)-Eu(III)-co-doped ZrO2 nanoparticles show a combination of their respective green and red emissions in addition to the blue emission attributed to defects of the silica host resulting in a pure white emission of coordinates x = 0.35; y = 0.33 in the CIE chromaticity diagram.


D-3:L05  Enhancement of Thermal Behavior of BaMgAl10O17:Eu2+ Blue Phosphors Using a Microwave Assisted Combustion Synthesis Process
A. POTDEVIN, N. PRADAL, G. CHADEYRON, ENSCCF, Institut de Chimie de Clermont-Ferrand, Clermont-Ferrand and Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Clermont-Ferrand; P. BONVILLE, CEA, Centre de Saclay, DSM/Service de Physique de l’Etat Condensé, Gif-sur-Yvette; R. MAHIOU, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Clermont-Ferrand and CNRS, UMR 6296, ICCF, Aubiere, France

Blue-emitting BaMgAl10O17:Eu2+, suitable for applications in a next generation of Hg-free lamps based on UV LED, was prepared by a microwave induced solution combustion synthesis, using urea as combustion fuel and nitrates as oxidizers. A reductive post-heating treatment has been used to reduce the residual part of trivalent europium, originating from the synthesis precursors. Structural and morphological properties of the outcoming phosphors have been studied by means of XRD and SEM. A pure well-crystallized and nanostructured BAM phase was obtained within only few minutes. An original study by magnetization and Mössbauer spectroscopy allowed us determining the relative amounts of Eu2+/Eu3+ in our samples. Furthermore, a complete study of powders optical features (photoluminescence excitation absolute quantum yields, emission spectra and decay curves) has been carried out. The thermal behavior of as-prepared and post-reduced powders has been investigated and compared to that of a commercial BAM, under conditions near to operating conditions of UV-LED based lighting devices. Powders stemming from combustion synthesis showed a better thermal behavior than commercial BAM with only a slight decrease of their luminescence intensity.


D-3:L06  The Dependence of Luminous Efficacies (LE) and Color Rendering Indices (CRI) of Simulated Warm-white pcLEDs on the Applied Red Emitting Phosphor
F. BAUR, T. JUESTEL, Münster University of Applied Sciences, Department of Chemical Engineering, Steinfurt, Germany

Solid state light sources for the generation of white light usually comprise a blue emitting (In,Ga)N semiconductor coated with a yellow emitting YAG:Ce phosphor. This is referred to as a phosphor-converted LED (pcLED). While high luminous efficacies (LE) can be easily achieved, the emitted light is cool-white since too little red light is emitted. The addition of a red emitter is a general concept to achieve warm-white light emitting pcLEDs. Since the human eye sensitivity is low in the red spectral range, this inevitably decreases the lamp’s LE. Thus, the choice of red emitter is crucial for achieving warm-white light while maintaining high LE. Mn4+ doped phosphors are well-known red emitters, suitable for excitation with a blue LED. The ion's peak emission strongly depends on the host material which in turn influences LE and CRI of the manufactured pcLED. In this work 24 simulated spectra with a correlated colour temperature of 2700 or 3000 K were created by the combination of a) a 450 nm or a 465 nm LED, b) YAG:Ce or LuAG:Ce and c) Mn4+-activated Mg14Ge5O24, Na3AlF6 or Ba2YNbO6. Of these spectra LE and CRI were calculated. The results yield insight into the optimal emission wavelength of Mn4+ in respect to obtaining a lamp spectrum that offers high LE and CRI.


D-3:L08  Luminescent Glasses and Glass Ceramics for White Light Emitting Diodes
F. STEUDEL1, A.C. RIMBACH2, S. LOOS2, B. AHRENS1, 2, S. SCHWEIZER1, 2, 1Fraunhofer Application Center of Inorganic Phosphors, Branch Lab of Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Soest, Germany; 2Department of Electrical Engineering, South Westphalia University of Applied Sciences, Soest, Germany

Luminescent glasses have recently become an interesting object of study due to their increasing importance in optical devices such as fiber lasers and light emitting diodes (LEDs). Within the framework of this paper, a series of rare-earth doped glasses are investigated for their potential application as photon converters for solid state lighting applications. Most white LEDs consist of a blue LED with a yellow phosphor on top. The phosphor powder is usually embedded in an organic polymer and directly coated onto the LED chip. However, heat-induced degradation of the encapsulant results in a decrease of efficiency and color temperature change over time. Luminescent glasses or glass ceramics represent an interesting alternative due to their higher thermal and chemical stability. Though, the “as-made” glasses provide already very promising optical properties, they can be further improved by subsequent thermal processing, resulting in luminescent glass ceramics. Interestingly, the color coordinates of rare-earth double-doped glasses can be tuned over a broad spectral range by changing the doping ratio of the rare-earth ions accordingly. In addition, double-doping allows for a change in color coordinates by using different excitation wavelengths.


D-3:IL09  From Red Band to Red Line Emitting Materials for Solid State Light Sources
T. JUESTEL, F. BAUR, Münster University of Applied Sciences, Department of Chemical Engineering, Steinfurt, Germany

Solid state light (SSL) sources for the generation of warm-white light most commonly comprise a blue emitting (In,Ga)N semiconductor equipped with a luminescent screen comprising a green to yellow emitting garnet or ortho-silicate type phosphor and a red emitting Eu2+-activated luminescent material. Due to the low sensitivity of the human eye to deep red emission beyond 650 nm, the emission band position and width of the red emitter strongly governs the luminous efficacy (LE) of SSL sources. Choosing the optimal red emitting phosphor is crucial for achieving warm-white light sources with a reasonable high LE and a high color rendering index (CRI). Simulations made by Zukauskas demonstrated that a luminescent material with a small full-width-half-maximum (FWHM) and a peak in the range 620-650 nm, is required to achieve high LE and CRI. The commonly applied Eu2+ phosphors possess a comparatively large FWHM. A viable alternative are red line emitters such as Eu3+, Sm3+, or Mn4+ with an FWHM of only a few nm. The peak emission wavelengths of these activator ions differ from each other and are also influenced by the host material. This contribution discusses the advantages and disadvantages of the various red emitting activator ions with regard to best possible LE and CRI values.


D-3:L10  High Efficient Phosphor Based on Ion-exchanged Sodium-zinc-aluminosilicate Glasses
Y.M. SGIBNEV, N.V. NIKONOROV, A.I. IGNATIEV, ITMO University, Saint-Petersburg, Russia

Silver molecular clusters (SMCs) in glass have a broadband and intensive luminescence in the visible range. Currently glasses with SMCs are attractive materials for many photonics applications: phosphors for white LEDs, luminescent waveguides, luminescent sensors, down-converters for solar cells, etc. SMCs in glass host can be formed by ion exchange that is low cost, flexible and effective method that allows getting high concentration of silver ions on the glass surface. We have studied influence of antimony ions on the spectral-luminescent properties of SMCs in glasses based on Na2O–ZnO–Al2O3–SiO2–NaF system doped with different quantity of antimony oxide (Sb2O3 =0%, 0.002%, 0.004% and 0.01% mol). Silver ions were introduced in the glass by low temperature IE and subsequent heat treatment. Antimony ions play a role of reducing agents for silver ions during the ion exchange and heat treatment processes. SMCs formed in the glasses by ion exchange have broadband and intensive luminescent in the visible and NIR ranges and absolute quantum yield reaches 63% (λex=360nm). Thermal treatment at 500oC (Tg=465 °С) results to formation of silver nanoparticles and luminescence quenching in the visible range.


D-3:L11  Luminescent Properties of Silver Molecular Clusters and Nanoparticles in Fluorine, Chlorine and Bromine Photo-thermo-refractive Glasses
N. NIKONOROV, V. DUBROVIN, A. IGNATIEV, D. IGNATIEV, D. KLUKIN, A. SIDOROV, ITMO University, St. Petersburg, Russia

Photo-thermo-refractive (PTR) glass is a very attractive material for recording volume phase holograms and developing a variety of laser devices. This silicate glass doped with silver and halogenides (F, Br, Cl) exhibits a growth of variety of crystalline phases of NaF, NaBr, NaCl, AgBr, AgCl on silver nanoparticles (NPs) and a refractive index modulation after exposure to UV radiation followed by a thermal treatment. In the present work spectral and luminescent properties of silver ions, molecular clusters (MCs) and NPs in fluorine, chlorine and bromine PTR glasses were investigated and some luminescent devices were demonstrated. It was shown that UV irradiation results in a substantial increase in the intensity of luminescence in the visible due to the transformation of charged MCs to the neutral MCs such as Ag2, Ag3, and Ag4. The heat treatment of PTR glasses below Tg promotes an increase in the intensity of luminescence at the expense of an increase in the concentrations of neutral MCs. The intensity of luminescence of PTR glasses decreases with temperature and increases with an increase in the NaCl or NaBr content of the glasses. The heat treatment of PTR glasses above Tg promotes the formation of metal silver nanocrystals and luminescence quenching.


D-3:L14  Plasmonic Enhanced Rare Earth Doping Quantum Cutting Phosphor for Si Solar Cells
DONG XIAO, TALIB HUSSAIN, HUIQI YE, LIANG TANG, Nanjing Institute of Astronomical Optics & Technology, Nanjing, Jiangsu, P.R. China

As quantum cutting material could split one high energy photon to two low energy photons, it could potentially improve the efficiency of the Si solar cell due to extra carriers generated in the short wavelength region. In order to improve the quantum cutting efficiency, we attach Au nanoparticles onto the YAG:Ce-Yb phosphor by a chemical method. The quantum cutting process in the YAG:Ce-Yb is influenced by the phosphor surface modification of Au nanoparticles which strongly enhanced the local surface electromagnetic field. The spectral data reveal the process details. We also apply the materials onto a Si solar cell chip.
 

Session D-4 - Advances in Scintillator Development

D-4:IL01  Advances in Scintillation Physics Toward Development of New and Improved Scintillators
G. BIZARRI, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

The search for new scintillators has become more and more sophisticated and increasingly successful in recent years. Current properties of modern scintillators are approaching the intrinsic limits imposed by the crystals. Nevertheless, demand continues for better scintillators for specific applications;. After discussing the basic concepts of scintillation in inorganic materials, the talk will focus on two research avenues that have contributed to the recent advancements in scintillator development and discovery. The first part of the talk will focus on how phenomenological/computational models have further revealed the complex entanglements between material and scintillation properties. The second part of the talk will emphasize how combinatorial strategies have allowed for rapid transfer and application of the fundamental concepts toward performance improvement. This approach, design of experiment, rapid growth/evaluation techniques and multivariable analysis, provides a versatile framework for rapidly unveiling and optimizing concealed correlations between material composition and performance.
This work is supported by the US Department of Energy/NNSA/DNN R&D and the US Department of Homeland Security/DNDO and carried out at LBNL under Contract no. DE-AC02- 05CH11231


D-4:IL02  Modelling Energy Deposition in Nanoscintillators to Predict the Efficiency of the X-ray-Induced Photodynamic Effect
A.-L. BULIN1, A. VASIL’EV2, A. BELSKY1, D. AMANS1, G. LEDOUX1, C. DUJARDIN1, 1Institut Lumière Matiére, UMR5306, Université Claude Bernard Lyon1-CNRS, France; 2Skobeltsyn Institute of Nuclear Physic, Lomonosov Moscow State University, Moscow

Scintillating nanoparticles (NPs) in combination with X-ray or γ-radiation have a great potential for deep tissue cancer therapy because they can be used to locally activate photosensitizers and generate singlet oxygen in tumours by means of the photodynamic effect. To understand the complex spatial distribution of energy deposition in a macroscopic volume of water loaded with nanoscintillators, we have developed a GEANT4-based Monte Carlo program. We thus obtain estimates of the maximum expected efficiency of singlet oxygen production for various materials coupled to PS, X-ray energies, NP concentrations and NP sizes. A new parameter, ηnano, is introduced to quantify the fraction of energy that is deposited in the NPs themselves, which is crucial for the efficiency of singlet oxygen production but has not been taken into account adequately so far. We furthermore emphasise the substantial contribution of primary interactions taking place in water, particularly under irradiation with high energy photons. The interplay of all these contributions to the photodynamic effect has to be taken into account in order to optimize nanoscintillators for therapeutic applications.


D-4:IL03  Recent Progress of Transparent Ceramic Scintillators
TAKAYUKI YANAGIDA, Nara Institute of Science and Technology, Takayama, Ikoma, Nara, Japan

Scintillators which convert the absorbed energy of the ionizing radiation to visible photons are widely used in industrial applications basic science studies. Although scintillators with a single crystal form have been utilized in practical applications due to their high optical qualities, transparent ceramic materials can be applied to scintillation detectors. As it is well known that the ceramics are made by sintering together a large number of single crystal grains, and that they can potentially be interesting for scintillator uses since a high mechanical strength and low fabrication cost are expected. Transparent ceramic is basically achievable in materials with a cubic structure, so garnet materials (e.g., YAG), sesquioxide materials (e.g., Lu2O3), complex perovskite (e.g., (LaSr)(AlTa)O3) and pyrochlore (e.g., La2Zr2O7) have been introduced for scintillator uses. In this presentation, I will review the recent progress of development of transparent ceramic materials focusing on their scintillation properties.


Session D-5 -  Upconversion Materials

D-5:IL01  Transparent Glass-ceramics Produced by Melting and Sol-gel. Crystallisation Mechanisms and Optical and Photonic Activity
G. GORNI1, J.J. VELÁZQUEZ1, R. BALDA2, J. FERNÁNDEZ2, Y. CASTRO1, M.J. PASCUAL1, A. DURAN1, 1Instituto de Cerámica y Vidrio (CSIC), Madrid, Spain; 2Dep. Física Aplicada I, Escuela Superior de Ingenieros, Bilbao, Spain

Oxyfluoride nano-glass-ceramics containing RE ions are extensively studied for their good mechanical and optical properties. They combine the very low phonon energy of fluoride nanocrystals able to host Ln3+ ions giving rise to high quantum efficiencies, with the high chemical and mechanical stability of silicate glass matrix. Melting Quenching (MQ) and Sol-Gel method (SG) have been used to prepare transparent glass-ceramics (GCs). One problem of MQ method is the evaporation of fluorine at high temperature. SG process is an alternative method that with lower processing temperatures allows a better control of composition, nano-crystal size and doping level, reaching much higher concentration of nano-crystalline fluorides and better homogeneity than with MQ method.
LaF3 based GCs were prepared by MQ (bulk materials and fibres) and by SG (bulk materials and thin films) and doped with Nd3+ to study up and down-conversion processes. Crystallization mechanisms were identified by DTA/TG. XRD, FTIR, UV-Vis, PL allowed to complete the structural and optical characterization. Studies of PL properties of MQ-GCs showed the possibility to obtain up and down-conversion signals due to in all the materials prepared. The effect and role of processing processes is analysed.


D-5:IL02  Plasmon Enhanced Luminescence Upconversion
WON PARK, University of Colorado Boulder, Boulder, CO, USA

Nonlinear optics has traditionally focused on frequency conversion based on nonlinear susceptibility but with the recent development of upconversion nanomaterials, luminescence upconversion is receiving renewed attention. Incorporating plasmonic nanostructures provides a promising pathway to further enhance the upconversion process. Naturally, many studies have been published in recent years, reporting enhancements of several hundreds to thousands. The enhancement mechanism however remains less clear partly because luminescence upconversion is a complex process involving multiple steps that may be affected differently by the plasmonic field. This paper will provide a comprehensive review, spanning from the fundamental quantum electrodynamics framework to synthesis and fabrication of plasmonic and upconversion nanomaterials and experimental demonstration of plasmon enhanced upconversion. This is an exciting topic both from the fundamental scientific perspective and also from the technological standpoints. It offers an excellent system to study how nonlinear optical processes are affected by the local photonic environments. At the same time, efficient upconversion could make significant impacts on applications such as solar energy conversion and biomedical imaging.


D-5:L04  Synthesis and Characterization of Bright Up-conversion Phosphor YTa7O19
SAKAYA TAMURA, K. TOMITA, Tokai University, Kanagawa, Japan; K. KATAGIRI, Hiroshima University, Hiroshima, Japan; M. KOBAYASHI, M. KAKIHANA, Tohoku University, Miyagi, Japan

Up-conversion (UC) phosphors emit visible (Vis) lights by excitation of near-infrared (NIR) lights through multiphoton multistep excitation. In many cases, the two type rare-earth (RE) ions are doped in UC host crystals. Er, Ho, and Tm emit Vis light, and Yb absorb NIR lights to act as photosensitizers for the other dopants. UC emission is achieved by energy transfer process between two RE ions. As a popular UC host crystal, fluorides such as NaYF4 have low phonon energy. On the other hand, oxide is low brightness from the effects of the high phonon energy. However, huge number of oxides were reported. In this work, oxide UC phosphors of various compositions were synthesized by parallel synthesis using an aqueous solution process and the UC emission characteristics were investigated. Under 980 nm NIR laser diode excitation, Er and Yb co-doped YTa7O19 showed intense green UC emission. Optimized doping amount were Er 10 mol% and Yb 40 mol%, and internal quantum efficiency of the best sample was 2.1 %. Tm and Yb co-doped YTa7O19 also showed bright blue UC emission. YTa7O19 has a layer structure in which RE ion sites are distributed two-dimensionally. Since the energy transfer is limited between RE ions in the layer, it is expected that efficiency of energy transfer is improved.

 
Session D-6 -  Optical Fibers; Sensing and Imaging

D-6:IL01  Luminescent Optical Fibers
D. DOROSZ, J. ZMOJDA, M. KOCHNOWICZ, P. MILUSKI, Bialystok University of Technology, Bialystok, Poland; J. PISARSKA, W. PISARSKI, University of Silesia, Katowice, Poland; M. FERRARI, IFN-CNR CSMFO Lab. & FBK CMM, Povo, Trento, Italy; G.C. RIGHINI, IFAC-CNR, Sesto Fiorentino, Italy

Rare-earth doped (RED) optical fibers made from multicomponent glasses give novel opportunities in such photonic devices as broadband ASE sources and luminescent fiber sensors. Since few years, the rapid development of co-doped optical fibers with unique luminescent properties arising from energy transfer between lanthanide ions has been observed. The multicomponent glasses offer more possibilities in management of optical radiation than classic silica glass. One of them is concerned with reduction of phonon energy which leads to increasing of quantum efficiency of radiative transitions and broadening of the spontaneous emission spectrum. Simultaneously, such photonic materials are characterised by good thermal stability which is required in optical fiber manufacturing. A good example is the antimony-germanate glass - a matrix of different phonon energies formed as a combination of glass-forming elements. The presentation will deal with spectroscopic properties of antimony-germanate glasses and double-clad optical fibers doped with terbium and europium ions sensitized by ytterbium. Relationship between composition of glass and luminescent properties of fabricated fibers co-doped with two different rare earth ions will be discussed.


D-6:IL02  Performances and Applications of Rare-earth Doped Silica-based Scintillating Fibers
A. VEDDA, Department of Materials Science, University of Milano-Bicocca, Milano Italy

The incorporation features of RE3+ ions in sol-gel silica are reviewed. Structural and vibrational studies, coupled to optical investigations, allow to find the most suitable RE concentrations and synthesis parameters for optimizing scintillation efficiency and RE dispersion, avoiding the formation of aggregates. Nano-aggregates are indeed formed for RE concentrations exceeding 1 mol%. Amorphous clusters are detected for Gd, Tb, and Yb doping. Moreover, cluster formation is sensitive to glass sintering conditions: amorphous Ce-based clusters or CeO2 nano-crystals are formed for reducing or oxidizing sintering atmosphere, respectively. Crystalline and highly luminescent Eu2Si2O7 nano-aggregates are found in SiO2:Eu [1]. After the description of advantages and challenges for the use of optical fibre based dosimeters during medical radiation therapy and diagnostic irradiations, recent results obtained by using Ce, Eu, and Yb doped optical fibres are described [2, 3]. Finally, the perspectives and open problems for the employment of silica fibres in high energy physics detectors are also discussed.
1. A. Baraldi et al, J. Phys. Chem. C 117, 26831 (2013); 2. I. Veronese et al, Appl. Phys. Lett. 105, 061103 (2014); 3. I. Veronese et al, J. Phys. Chem. C 119, 15572 (2015)


D-6:IL03  Versatile Lithium Fluoride Luminescent Detectors for High Resolution Imaging Applications from Extreme-ultraviolet to Soft and Hard X-rays
F. BONFIGLI, R.M. MONTEREALI, M.A. VINCENTI, ENEA C.R. Frascati, Photonic Micro and Nanostructures Laboratory, FSN-TECFIS-MNF, Frascati (Rome), Italy; E. NICHELATTI, ENEA C.R. Casaccia, Photonic Micro and Nanostructures Laboratory, FSN-TECFIS-MNF, S. Maria di Galeria (Rome), Italy

X-ray imaging represents a very relevant tool in basic and applied research fields due to the possibility to perform non-destructive investigations with high spatial resolution. We present innovative X-ray imaging detectors based on visible photoluminescence from aggregate electronic defects locally created in lithium fluoride (LiF) during irradiation. Among the peculiarities of these detectors, noteworthy ones are their very high intrinsic spatial resolution (intrinsic about 2 nm, standard about 300 nm) across a large field of view (>10 cm2) and wide dynamic range (>103). Photoluminescence response can be enhanced through the appropriate choice of reflecting substrates and multi-layer designs. This study is relevant for the most appealing X-ray imaging applications, as they will allow developing simple lensless imaging configurations with commonly-available laboratory polychromatic X-ray sources, as well as exploiting X-ray imaging-dedicated synchrotron beamlines in absorption and phase contrast experiments. X-ray micro-radiographies on LiF detectors of biological samples (also in vivo), geological samples and nano-structures obtained with extreme ultraviolet, soft and hard X-rays in different imaging configurations will be presented and discussed.


D-6:L07  Gas Effects on the Electrical and Photoluminescence Properties of Individual ZnO Nanowire 
F. RIGONI, C. BARATTO, M. DONARELLI, A. PONZONI, E. COMINI, G. SBERVEGLIERI, G. FAGLIA, Sensor Lab, Department of Information Engineering, University of Brescia & CNR-INO, Brescia, Italy

As a wide-bandgap semiconducting metal oxide (SMOX), ZnO turns out to be an attractive candidate for blue and UV optoelectronics. Many applications of SMOX materials like n-type ZnO are feasible, including single-wire transistors, gas sensors and, once put in contact with a p-type materials to create p-n junctions, nano-optoelectronic devices, e.g. UV LED. In this work we investigated the photoluminescence (PL), electrical and gas sensing properties of individual ZnO nanowire (NW) in a transistor configuration, varying the diameter of the nanowire. The choice of a single NW, instead of mesh of NWs with a wide diameters distribution, allows to better understand the properties of the material as function of the NW diameter. As the diameter of the NW decreases, a blue-shift in the near band edge (NBE) PL spectra at room temperature is observed. In order to understand the nature of this shift, PL spectra and PL imaging of the whole NW at 77 K has been carried out, which allow us to assign peaks corresponding to free exciton (FX), donor bound excitons (D0X) and optical phonon assisted free exciton FX-LO. Finally, oxidizing and reducing gases effect was investigated both on the electrical and the photoluminescence responses.

 
Session D-7 -  New Synthesis and Processing Methods

D-7:IL01  Activator-doped Amorphous Materials for Luminescent Application
HIROKAZU MASAI, Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan

Recently, rare-earth (RE)-free phosphors have attracted considerable attention because of their unique emission properties. Although ubiquitous elements for activator are fascinating, it is necessary to select an emission center exhibiting the high transition probability to attain high performance. The ns2-type emission center is one of the most favorable centers exhibiting high probability, which allows the use of practical phosphors such as Sb3+,Mn2+ co-doped calcium halophosphate. Since the ns2-type emission centers possess electrons in the outermost shell in both the ground and excited states, the emission is strongly affected by the coordination field. We have focused on the ns2-type emission center, in particular Sn2+ emission center, as an activator. The Sn2+ center is the most ubiquitous and environmentally friendly ns2-type center capable of blue light emission. Using this emission center, we have demonstrated the luminescence in amorphous materials. In this study, we report our recent results of luminescence of amorphous materials containing the ns2-type centers. It is found that the luminescent spectra have been changed depending not only on the chemical composition of the materials but also on the preparation process that affects the random network of glass.


D-7:L03  Silicon Oxycarbides with Transparency and Photoluminescence
MASAKI NARISAWA, H. INOUE, Graduate School of Engineering, Osaka Prefecture University, Sakai, Japan; F. FUNABIKI, Material Research Center of Elemental Strategy, Tokyo Institute of Technology, Yokohama, Japan; T. KAWAI, Graduate School of Science, Osaka Prefecture University, Sakai, Japan; H. HOSONO, Materials and Structure Laboratory, Tokyo Institute of Technology, Yokohama, Japan

Silicone microspheres mainly composed of methylsilsesquioxane units were pyrolyzed in a H2, Ar or CO2 atmosphere. Use of the H2 atmosphere accelerated mass loss at temperatures of 700-800 °C, and transparent Si–O–C(–H) ceramic microspheres were obtained after the pyrolysis. They exhibited photoluminescence under UV irradiation. Spin concentrations in these transparent spheres were 2 orders of magnitudes lower than those of black ceramics obtained in an Ar or CO2 atmosphere. PL color of the transparent spheres was uniform when an averaged diameter of the precursor was small. On the other hand, diversity of PL color became apparent when the averaged diameter of the precursor exceeded 10 micrometer. Hot presses with ultrahigh pressures were examined on H2 1100 (Si–O–C(–H) pyrolyzed in a H2 flow at 1100 °C). A hot pressing at 1100 °C and 4GPa yielded bulk materials. FTIR spectra in transmittance mode revealed existence of traces of Si-H and C-H groups in the Si-O-C(-H) bulk materials.


D-7:IL04  Three Primary Color Emission Up-conversion Phosphors for 3D Volume Display
KOJI TOMITA, S. TAMURA, M. TANAKA, Tokai University, Kanagawa, Japan; Y. SATO, Okayama University of Science, Okayama, Japan; M. KOBAYASHI, M. KAKIHANA, Tohoku University, Miyagi, Japan

Up-conversion (UPC) emission phenomena happen by multi photon excitation processes. Therefore UPC emission intensities are proportional to the square when the processes are two photon excitation, and are proportional to the cube in three photon excitation. Using this properties small point emission in a transparent volume is possible by focusing excitation lights. Full color 3D volume display which draws 3D images in a transparent volume can be fabricated using three primary color UPC phosphors. For such display three UPC phosphors which have high color purity of blue, green, red are necessary. We focused on the color purities, and prepared optimized UPC phosphors by parallel solution synthesis. Er, Yb doped YTa7O19 showed good green purity and high emission. Its quantum efficiency was 2.1%. For blue emission, Tm was doped instead of Er. Although the quantum efficiency was very low, YTa7O19 doped with optimized amount of Tm, Yb showed pure blue emission. Pure red emission was not observed in the YTa7O19 host crystal. On the other hand, Er, Yb doped Gd2O3 showed good red emission. Prepared three color UPC phosphors were dispersed in UV curable resin. Prototype of 3D volume display in which the three color phosphors were separately fixed as layers was fabricated by UV curing.


D-7:L05  Growth Kinetics of Colloidal CdSe Nanocrystals: Size and Size Distribution Control
E.A. SLEJKO, V. LUGHI, University of Trieste, Department of Engineering and Architecture, Trieste, Italy

The dependence of CdSe nanocrystals growth kinetics on growth temperature and oleic acid (OA) concentration has been investigated for a typical hot-injection synthesis. The growth temperature ranged between 210 °C and 270 °C while the cadmium-to-OA ratio ranged between 0.05 and 0.2; trioctilphosphine-selenium and cadmium oleate were used as precursors. The evolution of size and of size distribution of nanocrystals have been monitored during the synthesis via UV-Vis absorption and photoluminescence. Three key growth parameters have been extracted from the experimental data and discussed: the initial particle size right after the nucleation stage, the growth rate, the final particle size before the onset of the Ostwald ripening. The growth rate was found to be independent from the OA concentration, and to follow the Arrhenius law with an estimated activation energy of 0.43 eV/atom. Narrower size distribution, as well as a smaller initial and final particle size are favoured by increasing the OA concentration. Knowledge of the nanocrystal size at the end of the growth stage represents a valuable tool for designing the synthesis in order to obtain the desired particle size and size dispersion while maximizing the reaction yield.


D-7:IL06  Large-area Luminescent Phosphor Sheets for Lighting and Display Applications
H. MENKARA, PhosphorTech, Kennesaw, GA, USA

We report on large area luminescent phosphor sheet processing technology for lighting, display, and video applications. The sheets can be produced using roll-processing on a variety of large format substrates ranging from polycarbonate to flexible glass using conventional phosphors and other optical materials and structures. Both monochrome and patterned phosphor sheets have been demonstrated to date and widths up to 50 inch are possible with monolayer control over phosphor coating thickness. The technology is particularly suited for producing high color quality and fidelity solid-state lighting (SSL) devices and fixtures using blue or UV LEDs/lasers. LED lamps ranging from daylight to warm white have been produced with very high Color Rendering Index (CRI: 95-99), high Television Lighting Consistency Index (TLCI>95) and high Color Quality Scale (CQS>95). A custom red/green inorganic phosphor mixture coated on ultra-thin film has also been shown to deliver 100% of NTSC color gamut for LCD backlight applications.


D-7:IL07  Review of Phosphor Identification and Synthesis Methods
J. MCKITTRICK1, JUNGMIN HA2, ZHENBIN WANG3, G.A. HIRATA4, O.A. GRAEVE1, SHYUE PING ONG3, 1Dept. of Mechanical and Aerospace Engineering and Materials Science and Engineering Program, University of California, La Jolla, CA, USA; 2Materials Science and Engineering Program, University of California, La Jolla, CA, USA; 3Dept. Of Nanoengineering and Materials Science and Engineering Program, University of California, La Jolla, CA, USA; 4Center for Nanoscience and Nanotechnology, Ensenada, B.C. México

A higher quality white light can be generated through use of phosphor blends with a near UV-emitting (380-410 nm) LED, instead of a yellow-emitting phosphor and a blue-emitting LED. There are several basic properties that an ideal near UV phosphor should simultaneously possess. The quantum efficiency should be as high as possible and the excitation maximum should fall in the range where near UV LED emission is most efficient. Because of higher photon flux from LEDs, the phosphors are expected to operate at elevated temperatures, which require them to have reduced thermal quenching behavior. The phosphor must not degrade chemically or thermally and be free from photo-bleaching. The radiative lifetime of the activator ions should be short in order to reduce saturation effects and nonlinear, non-radiative recombination. Sub-micron or nanosize phosphors are needed for reduced light scattering.  It must be possible to economically manufacture the phosphor on a large scale. Finally, the phosphor should be non-toxic, and the fabrication, use, and disposal of the phosphor should be as environmentally benign as possible.  These topics will be addressed in this presentation. Also discussed is a combined first-principles modeling and experimental approach for the identification of phosphor hosts and activators. Phosphor synthesis methods and resultant particle characteristics will be discussed in the context of luminescence intensity.


D-7:L08  Fabricating Glasses with High Refractive Index and Strong Upconversion Luminescence using Containerless Processing
J. YU, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P.R. China

Titanium oxide glasses LaTi2.25O6 showing high refractive index was prepared by the aerodynamic levitation method. The thermal stability of these glasses was studied by DTA, and the effect of Yb3+ concentration on upconversion luminescence was investigated for the glass composition (La0.98-xEr0.02Ybx)(Ti0.95Zr0.05)2.25O6 (x=0~0.32, in steps of 0.04). Three emission bands centered at 535, 554, 672nm are obtained under the excitation of 980nm laser. When the Yb3+ concentration x is 0.16, the glass sample performs the strongest upconversion luminescence. The emission intensities at 535nm and 554nm are 47 and 51 times as high as that of Er3+-doped glass at room temperature.


D-7:L09  Synthesis of Ce:YAG Nanoparticles via the Formation of Urea Complexes
M.L. SALADINO1,2, F. ARMETTA2, C. GIORDANO3, E. CAPONETTI1,2, 1Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche - STEBICEF, Università di Palermo, Palermo, Italy; 2Centro Grandi Apparecchiature-UniNetLab, Università di Palermo, Palermo, Italy; 3Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Berlin, Germany

Yttrium Aluminium Garnet doped with cerium (Ce:YAG) is used in white LED devices, inorganic displays, X-ray scintillators and fluorescence thermometers. Since the optical properties of Ce:YAG nanoparticles (np) depend on particles size due to quantum size effect[1], the production of high-quality np is conditioned upon the use of fine, low-agglomerate powders. The aim of this work is to prepare Ce:YAG np with well-defined morphology, reduced sizes and hindered aggregation, simplifying at the same time the reaction conditions in order to scale up the synthesis. Ce:YAG np were prepared via the urea glass route[2] through the formation of complexes with different urea/metals molar ratio R and calcining the gels at suitable temperature. Structure, morphology and optical properties of the obtained powders, as well as the starting gel complexes were broadly investigated in order to understand the role of urea in the formation mechanism of the garnet phase. Results show that the gel formation and the suitable calcination temperature to obtain the garnet phase is influenced by R. Structure, particle size, morphology and optical properties of the np depend on R.
[1] Y. Djaoued et al. et al. J. Alloy. Comp. 508 (2010) 599; [2] C. Giordano et al. Chem of Mat. 21(21), (2009) 5136.

 
Session D-8 -  Advances in Characterization Techniques; Light Management for Active Applications

D-8:L01  Energy Transfer Probing of Nd3+ Doped Fluorescent Nanoparticles as an Agent for Near IR Bioimaging
Y. ORLOVSKII1,2, A. VANETSEV1, K. KALDVEE1, E. SAMSONOVA1, I. SILDOS1, 1Institute of Physics, University of Tartu, Tartu, Estonia; 2Prokhorov General Physics Institute RAS, Russia, Moscow

We employed energy transfer probing as a new tool for characterization of Nd3+ doped nanoparticles (NPs) as a fluorescent agent for near IR bioimaging. It is based on the analysis of static Förster and fluctuation kinetics of impurity quenching. We compared quantitatively the fluorescence quenching in the KY3F10, KYF4, and YPO4 water-dispersible Nd3+ doped NPs synthesized by microwave-hydrothermal treatment. As a result we revealed that the OH quenching acceptors are distributed in the volume of the NPs, rather than on their surface. The result may be extended to all NPs synthesized by water-based techniques. Therefore, all of the previously obtained results concerning the fluorescence quenching of such NPs should be reviewed in the light of the new data on the actual source of the quenching. We found minimum fluorescence quenching and accordingly maximum fluorescence quantum yield for the Nd3+: KY3F10 nanocrystals, which is in agreement with the amount of OH molecular groups in the volume of the NPs estimated from Förster kinetics. The analysis of the kinetics at 1% Nd3+ concentration revealed the realization of the late fluctuation stage. The formation of the fluctuation stage confirmed the high concentration of the OH acceptors in the volume of the NPs compared to Nd3+ ions.


D-8:IL02  Autocorrelation Analysis for the Unbiased Determination of Power-Law Exponents in Single-Quantum-Dot Blinking
J. HOUEL, G. LEDOUX, D. AMANS, A. AUBRET, C. DUJARDIN, F. KULZER, Institut Lumière-Matière, CNRS UMR5306, Université Lyon 1, Université de Lyon, Villeurbanne CEDEX, France; Q.T. DOAN, T. CAJFINGER, A. DOMINJON, S.FERRIOL, R. BARBIER, Institut de Physique Nucléaire de Lyon, CNRS UMR5822, Université Lyon 1, Université de Lyon, Villeurbanne Cedex, France; M. NASILOWSKI, E. LHUILLIER, B. DUBERTRET, ESPCIParisTech, PSL Research University, CNRS, Sorbonnes Université, UPMC Paris VI, Paris, France

We present an unbiased and robust analysis method for power-law blinking statistics in the photoluminescence of single nano-emitters, allowing us to extract both the bright- and dark-state power-law exponents from the emitters' intensity autocorrelation functions [1]. As opposed to the widely-used threshold method, our technique therefore does not require discriminating the emission levels of bright and dark states in the experimental intensity timetraces. We rely on the simultaneous recording of 450 emission timetraces of single CdSe/CdS core/shell quantum dots at a frame rate of 250 Hz with single photon sensitivity. Under such experimental conditions, our approach can determine ON and OFF power-law exponents with a precision of 3% from a comparison to numerical simulations, even for shot-noise-dominated emission signals with an average intensity below 1 photon per frame and per quantum dot. These capabilities pave the way for the unbiased, threshold-free determination of blinking power-law exponents at the micro-second timescale.
[1] J. Houel et al., ACS Nano 9, 886 (2015)


D-8:IL03  Simultaneous Vibrational and Optical Spectroscopy for the Study of the Local Structure and Optical Properties of Luminescent Ions in Phosphors
M. KARLSSON, Chalmers University of Technology, Goteborg, Sweden

Phosphor converted LEDs are presently revolutionising lighting as they offer tremendous energy savings over traditional light sources. The phosphors often consist of a crystalline oxide host lattice containing a small amount of so called activator ions, which convert light to longer wavelength via an electronic transition. Although the activator ions have intrinsic characteristics that contribute to the optical properties of phosphors, the static and dynamic structure of the host lattice ultimately determine phosphor performance. Understanding the coupling between optical properties and atomic-scale structure and dynamics is therefore important for the development of new phosphors. However, the presence of defects and/or local structural distortions complicates the description of the optical properties of phosphors and still they are not fully understood for any material; hence more investigations are needed. In this presentation, I will present new results related to the local structure and vibrational dynamics of the well known phosphor Ce3+-doped Y3Al5O12, as obtained from simultaneous mode-selective vibrational and optical spectroscopy experiments. A key result is the observation of specific phonon modes and local structures affecting the emission intensity of the phosphor.


D-8:IL04  Photon Management with Luminescence Structures
S. NORMANI, M. SALHI, A. BRAUD, J.L. DOUALAN, R. MONCORGÉ, G. BRASSE, P. CAMY, CIMAP, Caen, France

Luminescence properties of rare earth ions in materials such as fluoride crystals or chalcogenide glasses can be adjusted with aid of energy transfers or excited state absorption (ESA) mechanisms. Materials with high proportion of ion clustering such as fluorites are particularly interesting to study the energy transfers and there consequences. These processes can be used to emphasize or to avoid specific transitions. ESA can also be a very interesting tool to convert photons from the mid Infrared to the visible domain. Thus, in this communication, recent potential applications resulting from this “photon management” that can be achieved in rare-erath doped luminescent materials will be presented in the fields of lasers and sensors.


D-8:L05  Synthesis and Luminescence Properties of Ce doped LiCaPO4 Phosphor for Radiation Dosimetry
S.K. OMANWAR, C.B. PALAN, N.S. BAJAJ, Department of Physics, Sant Gadge Baba Amravati University, Amravati, India

The LiCaPO4:Ce phosphor is synthesized using modified solid state reaction. The uniform particles are obtained and confirmed by XRD and SEM. The average particle size is also determined by Debye Scherrer formula. The LiCaPO4:Ce phosphor has been investigated for its photoluminescence (PL), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties. PL spectra showed the emission of Ce ion at 381 nm when excited by 313 nm. The TL parameters such as activation energy, frequency factor and order of kinetics were determined. The CW-OSL studies reveal that the phosphor has better sensitivity than α-Al2O3:C (BARC) however it is found to decay faster.

 
Session D-9 -  Methods to Integrate Luminescent Materials in a Device

D-9:IL01  Electrophoretic Deposition of Phosphors for Solid-state Lighting
J.B. TALBOT, Dept. of NanoEngineering, University of California, San Diego, La Jolla, CA, USA

Electrophoretic deposition (EPD) is a coating method in which charged particles in a suspension are deposited onto an oppositely charged substrate under the force of an applied electric field. EPD has many advantages such as benign processing conditions, the ability to produce uniform deposits quickly and continuously, and a low level of contamination. A wide variety of phosphors (oxides, nitrides, silicates, phosphates) have been deposited by EPD for the application of solid-state lighting. EPD has been used to coat a uniformly thin, highly-packed conformal layer (deposited directly on a blue-emitting LED) and a thick layer for a remote configuration (deposited on a substrate above either a blue-emitting or near UV-emitting LED). Films of different blended phosphor compositions and sequentially-deposited layered films of phosphors have been deposited to produce white light. Micron, nano-size and core-shell phosphor particles have been deposited and compare using EPD. EPD has advantages for controlling color and efficiency of solid-state lighting devices by coating single layers, multiple layers or blends of phosphor particles.


D-9:IL03  Temperature Sensing via Downconversion Luminescence of Lanthanide Doped Metal Oxides
M.D. DRAMICANIN, University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

The changes of luminescence properties of materials with temperature (such as changes of absolute and relative emission intensities, lifetime values of excited states, emission rise times, peak positions, and emission bandwidths) allows some materials to act as sensitive thermometers. The phenomenon become the basis of a new arm in the field of luminescence spectroscopy commonly termed as a luminescence thermometry, which presents many prospective applications including temperature measurements at the nanoscale. This lecture presents an overview of lanthanide doped metal oxides developed for temperature sensing via downconversion luminescence. Different modalities of luminescence thermometry are discussed, such as the use of materials with a single- or multi- emission centers, the selection of the reference emission, and advantages or disadvantages of the emission intensity measurements versus measurements of temporal changes in emission. Figures of merit of measurements (like temperature sensitivities, resolutions, measurement ranges) are compared between different lanthanide ions and metal oxides. Also, several examples of temperature sensing using lanthanide doped metal oxides will be given with an emphasis on the measurements at the nanoscale and in the harsh environments.


Session D-10 -  Medical Applications and Bioimaging

D-10:IL02  Design, Functionalization and Use of Persistent Luminescence Nanocrystals
E. TESTON, T. MALDINEY, J. SEGUIN, N. MIGNET, D. SCHERMAN, C. RICHARD, Unité de Technologies Chimiques et Biologiques pour la Santé; UMR 8258 CNRS; U 1022 Inserm; Université Paris Descartes, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France; Chimie-ParisTech, Paris, France

Optical imaging has become a dominant visualization method in biomedical research due to its high sensitivity, low cost and its ease of use. However, tissue autofluorescence produces a substantial background signal that severely limits the quality of images. To overcome this limitation, our team pioneered the use of persistent luminescence nanoparticles for optical real-time imaging in small animals. These nanocrystals have the ability to store the excitation light in traps and to emit light from minutes to hours after the end of the excitation, through a thermal activation in tissues. This property allows the detection of PLNP in tissues with high target to background ratio. The first generation of PLNP was a silicate doped with Eu2+, Dy3+ and Mn2+. It was synthesized by a sol-gel process allowing getting nanoparticles. The search for new optical probes, with improved optical property, has led us to a new family of materials, a zinc gallate doped with 0.25% of Cr3+ and synthesized by a hydrothermal process. During this seminar, I will report the design and synthesis of different nanocrystals prepared in our lab and give examples of their use for in vivo optical imaging.


D-10:IL03  Inorganic Fluorescent Materials for Biophotonics in the Second Biological Window
KOHEI SOGA, Department of Materials Science and Technology, Tokyo University of Science, Tokyo, Japan Imaging Frontier Center, Tokyo University of Science, Tokyo, Japan

The wavelength range between 1000-1700 nm has recently called as “over 1000-nm near infrared (OTN-NIR)” or the “Second Biological Window (SBW)” since the optical loss is almost ten times less in the window compared to the conventional one. The author’s group has developed the materials and system for fluorescent bioimaging in the SBW for a decade. Major luminescent materials in the SBW are rare-earth doped ceramic nanoparticles (RED-CNP), quantum dots and carbon nanotubes (CNT). To make those particles work in biological system, as well as for keeping them mono-dispersed, incorporation of these inorganic materials with biofunctional polymers is inevitable. Beside the materials development, the grout has developed both micro- and small animal fluorescence bioimaging system for the SBW. The OTN-NIR small animal imaging system, which has been developed by the collaboration of the group and Shimadzu Co., Japan now has been launched to market in Japan. The presentation will overview the development both in materials and systems for the biophotonics in the SBW.


D-10:IL04  Photoluminescent Color Center-based Lithium Fluoride Radiation Detectors for Proton Beam Diagnostics
M. PICCININI, A. AMPOLLINI, L. PICARDI, C. RONSIVALLE, M. VADRUCCI, F. BONFIGLI, S. LIBERA, E. NICHELATTI, M.A. VINCENTI, R.M. MONTEREALI, ENEA, C.R. Frascati, FSN-TECFIS, Frascati (RM), Italy

Lithium fluoride (LiF) is a well-known dosimeter material and is sensitive to any kind of ionizing radiation. A linear accelerator for protontherapy under development at ENEA was used, to irradiate at room temperature with proton beams of 3 and 7 MeV energy, LiF crystals and thin films in a dose range from 1000 to 10000000 Gy. The irradiation of LiF induces the formation of stable F2 and F3+ color centers (CCs), which emit with broad photoluminescence (PL) bands in the visible. By acquiring the PL image of the irradiated spots with a conventional fluorescence microscope, the transversal proton beam intensity was mapped with a high spatial resolution and also allowed measuring the integrated PL intensity as a function of the irradiation dose: LiF films showed a linear PL response extending over three orders of magnitude of dose range, independently on the beam energy. It was also possible to measure the CCs PL distribution with proton penetration depth and direct imaging the Bragg peak, which gives an estimation of the proton beam energy. The sensitivity of the optical reading techniques and the high emission efficiency of CCs provided encouraging results. Further experiments are under way, to optimize the PL reading techniques for proton beam dosimetry and imaging applications.

 
Poster Presentations

D:P01  FRET between Inorganic Luminescent Quantum Dots and New Novel Organic Fluorescent Derivative
G.H. PUJAR1, N. DESHAPANDE2, I.M. KHAZI2, S.R. INAMDAR1, 1Laser Spectroscopy Programme, Department of Physics, and UGC-CPEPA, Karnatak University, Dharwad, India; 2CPEPA, Department of Chemistry, Karnatak University, Dharwad, Karnataka, India

We have designed and synthesised a novel molecule 2-(4-((E)-2-(5-((E)-4-(5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl)styryl)thiophen-2-yl)vinyl)phenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole based on Donor-π-Acceptor strategy by employing Wittig reaction. The structural integrity of the new compound was confirmed by 1H NMR, 13C NMR, LC-MS analysis, DFT computations and thermal studies (TGA and DSC). The HMF-ZnSe/ZnS core-shell QDs (7 nm and 8 nm) and this novel fluorescent derivative were specially chosen as the energy donor and acceptor to study fluorescence resonance energy transfer (FRET) employing steady state and time resolved spectroscopy techniques. The results reveal that the FRET pairs (i) show a strong dipole-dipole interaction tendency to transfer energy from donor to acceptor, (ii) demonstrate high FRET efficiency and (iii) display a strong dependence of the acceptor fluorescence emission on overlap integral, size of the QDs and distance between donor and acceptor. Dynamic quenching too is noticed to occur in the present FRET system. Stern–Volmer (KD) and bimolecular quenching constants (kq) are determined from the Stern–Volmer plot. It is observed that the transfer efficiency follows linear dependence on the spectral overlap as predicted by the Förster theory.


D:P06  Effect of Process Parameters on Luminescent Properties of Eu,Tb,Tm Codoped CaMoO4 Thin Films
A.P.A. MARQUES, A.S.M. CHARALABOPOULOS, F.S. TAVARES, UNIFESP, Diadema, SP, Brasil; F. V. MOTTA, UFRN, Natal, RN, Brasil; M.S. Li, USP, São Carlos, SP, Brasil; E. LONGO, UFSCar, São Carlos, SP, Brasil

The search for a stable inorganic phosphor based on rare earth with a high emission in blue, green and red spectral region, with potential to white emission, is an attractive and challenging research assignment. The Calcium molybdate (CaMoO4), inorganic material of this research, have applications in various fields such as phosphors, optical fibers, scintillators, magnets and catalysts. In this study CaMoO4 was codoped with three different earths rare: europium, terbium and thulium ions. CaMoO4:Eu,Tb,Tm (CMO:ETT) thin films were prepared from method Complex Polymerization (CP). The effect of the experimental parameters on the morphology, particle size, sample uniformity and optical properties of the CaMoO4 doped thin films were studied. The precursor resin of CMO:ETT was deposited onto Si wafers by means of the spinning technique. The structure and optical properties of the resulting films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and Photoluminescence (PL) measurements. XRD characterization showed that thin films presented the scheelite-type crystalline phase. AFM analyses showed a considerable variation in surface morphology by comparing samples heat-treated at 300 and 900°C.
Work supported by FAPESP #2013/07437-5.


D:P08  Luminescent Fluorine Phosphate Glasses Doped with CdS CdSe, PbSe and PbS Molecular Clusters and Quantum Dots for Lighting and Solar Cells Converters
E. KOLOBKOVA, ZH. LIPATOVA, N. NIKONOROV, St. Petersburg, ITMO University, Saint-Petersburg, Russia

Optical composite materials containing CdS, CdSe, PbSe and PbS quantum dots (QDs) are widely used in optics and photonics. Such materials possess luminescence in visible (CdS, CdSe) and near IR (PbSe, PbS) spectral region. In the present work luminescent properties of fluorophosphate glasses doped with CdS, CdSe, PbSe and PbS are disscused. The luminescence in a visible region with absolute Quantum yield (Q.Y.) up to 10% in as-prepared (before thermal treatment) fluorophosphates glasses (FPG) with Cd, Pb, Se and S ions was observed. This indicates the presence of (PbSe)n ,(CdS)n, (CdSe)n and (PbS)n molecular clusters (MCs) in the glasses. These MCs play the role of crystallization centers for quantum dots during heat treatment. Within heat treatment QD are formed and the absolute Q.Y. encreased up to 60-70%. The influence of heat treatment on luminescent properties of the MCs and QDs was studied. New luminescent fluorophosphates glasses with MCs and QD are promising as phosphors in photonic devices, down-converters of solar radiation in solar cells, and in luminescent fiber temperature sensors and dosimeters of UV radiation.


D:P21  Crystal Orientation and Grains Morphology in Polycrystalline YAP Ceramics
D. MICHALIK, T. PAWLIK, B. CHMIELA, Silesian University of Technology, Katowice, Poland

Yttrium aluminum perovskite as the one of the equilibrium phase in the Al2O3-Y2O3 system shows high thermal stability and good chemical resistance. Doped by RE3+ it found a place in the optical application. High quality of polycrystalline YAP ceramics give them a chance to compete with monocrystal materials. This work shows results of the microstructure analysis of polycrystalline YAP specimens using scanning electron microscopy (SEM) accompanied by the outcome of energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) studies. The initial powders of YAP-RE3+ were obtained by both, the solid state reaction or wet chemical methods. Then they were compacted by cold isostatic pressing at 250MPa. Finally, the samples were densified at 1650 °C in the air atmosphere. The resultant pellets were cut and polished parallel and perpendicular (horizontally and vertically) to the top surface. Crystal orientation, grain size and grain boundaries between the main phase and impurities were observed and described in all analyzed samples.


D:P26  Solid State Synthesis of SrSi2O2N2:Eu2+ Powder in Flowing Nitrogen
T. PAWLIK, D. MICHALIK, M. SOPICKA-LIZER, Silesian University of Technology, Katowice, Poland   

Oxynitride compound SrSi2O2N2 is a good material as a host lattice for the phosphor material application due to the highly covalent bonds. SrSi2O2N2 doped by Eu2+ shows a broad green band emission spectrum. The present paper shows results of Eu2+ concentration on photoluminescence properties. The phase composition was checked by X-ray diffraction method. Morphology of the resultant powders were examined by the scanning electron microscopy. The effect of Eu2+ concentration was analyzed by photoluminescence measurements. The obtained results show the a diverse quenching concentration effect. Apart from that, preparation method can influence the actual value of dopant accommodated into the host lattice.


D:P29  Encapsulation of Oxynitride Phosphors into Sintered Na2O-ZnO-B2O3-P2O5 Glass Body
NANAKO AKIYAMA1, H.T. HINTZEN2, K. ITATANI1, 1Department of Materials and Life Sciences, Sophia University, Tokyo, Japan; 2Faculty of Applied Science, Delft University of Technology, Delft, The Netherlands

The conditions for the fabrication of transparent glass body in the Na2O-ZnO-B2O3-P2O5 system were examined by a pressureless firing and subsequent oxygen-supplied hot isostatic pressing (O2-HIP). The starting glass was prepared by melting the mixture of NaH2PO4, ZnO, H3BO4 and H3PO4 at 1100ºC, followed by quenching on copper plates cooled by liquid nitrogen. The glass compact was pressurelessly-fired at 350ºC for 20 min in order to remove open pores, and the subsequent O2-HIP treatment at 350ºC for 24 h under the pressure of 130 MPa resulted in the transparency. When the oxynitride phosphors, i.e., blue-emitting (La0.96Ce0.04)3Si8O4N11 and yellow-emitting (Ca0.97Eu0.03)Si2O2N2, were encapsulated into the glass, no peak shifts in the emission/excitation spectra were found, which demonstrated that no degradation of phosphors has occurred during the encapsulation operation conducted under the same conditions described above. Pseudo-white light emission was observed by the equi-mass addition (total amount: 3 mass%) of (La0.96Ce0.04)3Si8O4N11 and (Ca0.97Eu0.03)Si2O2N2. Overall, the transparent glass body could be fabricated by the pressureless firing and subsequent O2-HIP treatment, and the phosphors were encapsulated into the glass without significant degradation.


D:P31  Synthesis and Characterization of Lanthanide Metal-organic Frameworks with Perfluorinated Linkers
A. LAURIKENAS, J. BARKAUSKAS, A. KAREIVA, Department of Inorganic Chemistry, Vilnius University, Vilnius, Lithuania

Metal-organic frameworks (MOFs) based on lanthanide metal ions or clusters represent a group of porous materials, showing interesting coordination and optical properties. MOFs present opportunity for tuning the luminescence behavior because of the possibility to trap in the network pores molecules which can influence the lanthanide emission. In this study, the MOFs based on the lanthanide series and 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylic acid (TFBDC) were synthesized by precipitation and diffusion-controlled precipitation methods. Powders insoluble in aqueous media and polar solvents were obtained. The microstructure and properties of lanthanide-containing MOFs were evaluated and discussed. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS) were used to characterize crystallinity, structural features and chemical composition of synthesized MOFs.


D:P33  Synthesis and Characterization of PLD Glass Phosphate Films doped with CdS Powder
M. ELISA, I.C. VASILIU, I.D. FERARU, R. IORDANESCU, National Institute of R&D for Optoelectronics INOE 2000, Magurele, Jud. Ilfov, Romania; G. EPURESCU, M. FILIPESCU, National Institute for Laser, Plasma and Radiation Physics, Magurele, Jud. Ilfov, Romania; C. PLAPCIANU, C. BARTHA, M. ENCULESCU, National Institute of Materials Physics, Magurele, Jud. Ilfov, Romania; S. PERETZ, Institute of Physical Chemistry “I. Murgulescu”, Romanian Academy, Bucharest, Romania

In the present work optical, structural and morphological properties of CdS-doped phosphate films obtained by PLD (Pulsed Laser Deposition) method were investigated. In the deposition process a target based on a mixture composed of Li2O-Al2O3-BaO-La2O3-ZnO-P2O5 glass and CdS powder as dopant was used. Initially, the phosphate glass was obtained by non-conventional wet route of raw reagents processing followed by melting-quenching technique. The obtained glass was grinded and mixed with 3 wt. % CdS powder, by mechanically homogenization. The mixture was compressed to obtain a cylindrical sample which was heat treated for 2 h, at 500o C in an inert gas atmosphere, in order to sintering the material and to obtain the target used in PLD deposition process of the films on silicon substrate. The X-ray Diffraction analysis put in evidence crystalline compounds specific to phosphate matrix and dopant. It was found that the luminescence spectra show a broad band located at approximately 430 nm provided by 350 nm excitation. FTIR and Raman spectroscopy revealed specific vibration modes of vitreous inorganic matrix and Cd-S bond from the dopant. The morphology of the deposited film was investigated by scanning electron microscopy (SEM), showing in evidence spherulitic units specific to PLD films. Energy Dispersive of X-ray found an elemental composition in the deposited films similar to that of the glass target, proving the reproducibility of the chemical content of the target in the PLD process.


D:P42  YAGG:Cr3+ as NIR Persistent Phosphor for In Vivo Imaging
O.Q. DE CLERCQ, J.H. BOUMAN, P.F. SMET, D. POELMAN, Lumilab, Ghent University, Ghent, Belgium; K. BRAECKMANS, Bio-Photonic Imaging Group, Ghent University, Ghent, Belgium

The use of infrared emitting persistent phosphors for medical imaging is a novel application in the field of persistent luminescence [1]. Current research focuses on host materials doped with Mn2+ or Cr3+, as these transition metals show emission at wavelengths larger than 600 nm [2], which falls in the tissue transparency window. We focus on Cr3+-doped Y3Al5-xGaxO12 (YAGG). Ceramic YAGG discs have been shown to exhibit persistent properties, with afterglow intensities five times brighter than the popular ZnGa2O4:Cr3+ phosphors [3]. We check the influence of codoping YAGG:Cr3+ powders with lanthanides on the persistent luminescence intensity and duration. Thermoluminescence experiments are conducted to investigate the variation in trap depth upon codoping. The influence of different synthesis conditions is also checked, as is the relation between crystallite size and the persistent properties of the material.
[1] le Masne de Chermont et al., PNAS 104, 9266 (2007). [2] Zhuang et al., Opt. Mater. 36, 1907 (2014). [3] Xu et al., APEX 8, 042602 (2015).


D:HP43  Cd-free Quantum Dot Dispersion in Polymer and their Film Molds
YUYANG SU, KAILING LIANG, CHYI-MING LEU, Industrial and Chemical Research Institute (ITRI), Material and Chemical Research Laboratories (MCL), Hsinchu, Taiwan

Indium phosphide (InP) quantum dots (QDs) with luminescence tunable over the entire visible spectrum were prepared by the conventional hot injection method. InP QDs are considered alternatives to Cd- containing QDs for application in light-emitting devices because of showing similar optical properties to those containing toxic heavy metals. The multishell coating with ZnS/ZnS or ZnS/SiO2 was shown to improve the photoluminescence quantum yield (QY) of InP QDs more strongly than the conventional ZnS shell coating. QY values were more than 60% along with FWHM of 41-63 nm can be routinely achieved, making the optical performance of InP/ZnS/ZnS or InP/ZnS/SiO2 QDs comparable to that of InP/ZnS QDs.


D:HP44  Study of Crystallization of Tm2Ti2O7 Powder under Non-isothermal Conditions
M. MARINOVIĆ - CINCOVIĆ, B. MILIĆEVIĆ, S. KUZMAN, M. DRAMIĆANIN, Institute of Nuclear Sciences “Vinča”, University of Belgrade, Belgrade, Serbia

The crystallization process of Tm2Ti2O7 has been studied under non-isothermal conditions. In order to characterize the precursor’s powders and final product of crystallization, several experimental techniques were used: simultaneous thermogravimetric (TG), differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis.Kinetic parameters were calculated with non-isothermal methods based on the Arrhenius equation: Kissinger and Ozawa peak methods.It was found that all curves are shifted to a higher temperature with an increase of heating rate, verifying that thermal activation steps occur during the crystallization process. The crystallization peaks appeared in the temperature range of 1058-1125 K. Apparent activation energy of crystallization under linear heating condition were obtained from the temperature dependence of the exothermic peak on the heating rate: (812 ± 50) kJ/mol and (790 ± 50) kJ/mol, for Kissinger and Ozawa method, respectively. The average values of the activation energy were obtained by two isoconversion methods.These results were in a very good agreement with methods based on the Arrhenius equation and corresponds to the values of activation energy: (820 ± 20) kJ/mol and (845 ± 20) kJ/mol, for FWO and KAS method, respectively.


D:HP45  Effect of a Confined Environment on the YAG Nanopowder Features
D. CHILLURA MARTINO1, F. ARMETTA1,2, M.L. SALADINO1.2, R. LOMBARDO1, E. CAPONETTI1.2, 1Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche - STEBICEF, Università di Palermo, Palermo, Italy; 2Centro Grandi Apparecchiature-ATEN Center, Università di Palermo, Palermo, Italy

The goal of this work is investigate the role of the microemulsion confined environment on the formation of yttrium aluminium garnet (YAG, Y3Al5O12) nanopowders. The synthesis of the precursors has been performed in a water/CTAB/n-butanol/n-heptane microemulsion followed by a calcination process.
The phase behaviour of the microemulsion has been investigated on increasing the water solutions (of reactants) content (R). Small angle X-ray scattering data analysis reveals that as function of R, ammonia solution organize the system in water in oil microemulsion, bicontinuous and lamellar phases, instead the yttrium and aluminium nitrates solution prevent the formation of the lamellar phase. The precursor synthesis has been performed by mixing two microemulsions containing reactants. R=20 and 70 amounts have been choice because at these value both microemulsion are bicontinuous but with different domain size and order degree. YAG nanopowder, obtained from precursor calcination, has been characterized by means of wide angle X-ray diffraction and transmission electron microscopy. At R=20 the nanoparticles were regular in size and in shape with high tendency to agglomerate. At R=70 the nanoparticles were spherical but polydisperse in size and with low agglomeration degree.


D:HP46  Luminescence Properties of Ytterbium Activated PLZT Ceramics
M. PLONSKA1, J. PISARSKA2, W.A. PISARSKI2, 1University of Silesia, Faculty of Computer and Materials Science, Institute of Technology and Mechatronics, Division of Electroceramics and Micromechatronics, Sosnowiec, Poland; 2University of Silesia, Faculty of Mathematics, Physics and Chemistry, Institute of Chemistry, Katowice, Poland

Lanthanum modified lead zirconate titanate (PLZT) ceramics, has been known as ferroelectric material with perovskite structure and presents various structural phases, dielectric and optical properties depending on its chemical composition. Co-doping with other rare earth ions (RE3+) causes modified PLZT:RE3+ ceramics to become a luminescent laser-host active medium.In the present work the influence of co-doping with ytterbium ions on physical properties of 8/65/35 PLZT was studied. The ceramic powders were synthesized by the modified sol-gel method, and underwent consolidation by pressure-less sintering techniques, in Ts=1200°C/6h. Our investigations offer a detailed account of the relationships between concentrations of trivalent ytterbium ions in PLZT matrix, on their structure, microstructure, as well as luminescence properties. Near-infrared luminescence spectra at about 1020 nm were recorded, which correspond to 2F5/2 - 2F7/2 transition of Yb3+. Based on decay measurements, the luminescence lifetimes for the 2F5/2 excited state of Yb3+ were determined.
The present research has been supported by National Science Centre in years 2013-2017, as a research project No UMO-2012/07/D/ST8/02634.


D:HP47  Characterization of Lead Lanthanum Zirconate Titanate Ceramics Co-doped with Lanthanide Ions
J. DZIK, M. PLONSKA, University of Silesia, Faculty of Computer Science and Materials Science, Institute of Technology and Mechatronics, Division of Electroceramics and Micromechatronics, Sosnowiec, Poland

The aim of this work was to obtain Pb0.92(La0.08)(Zr0.65Ti0.35)0.98O3 materials co-doped with two different lanthanide ions (Ln3+) and characterization how they influence the physical properties of prepared 8/65/35 PLZT: Ln3+ ceramics. As a co-dopant, praseodymium (Pr3+) and neodymium (Nd3+) ions were used at the concentration of 0.0 and 0.5 wt.% respectively. The ceramic powders of 8/65/35 PLZT, PLZT:Pr3+ as well PLZT:Nd3+ were synthesized by conventional ceramic route, from high purity raw oxide materials (>99,9%). All compositions of the ceramic samples were sintered via single time process at Ts=1200°C/3h, by uniaxial hot pressing. Performed measurements have shown dependence of used dopant on structure, microstructure, and dielectric as well optical properties of the fabricated 8/65/35 PLZT: Ln3+ materials.
The present research has been supported by National Science Centre in years 2013-2017, as a research project No UMO-2012/07/D/ST8/02634.
 

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