Željka Antić

Self-referenced luminescence thermometry with Sm3+ doped TiO2 nanoparticles

The performance of Sm(3+) doped TiO2 nanoparticles for luminescence temperature sensing was tested over a temperature range from room to 110 °C. The Sm(3+) ions were incorporated into TiO2 nanocrystals using hydrolytic sol-gel route. Microstructural characterization of the obtained material was performed using transmission electron microscopy and x-ray diffraction measurements. Luminescence emission spectra of Sm(3+) doped TiO2 nanoparticles consists of two distinct spectral regions: the high energy region associated with the trap emission of the TiO2 host, and the low energy region with well-resolved emission peaks of the Sm(3+) ions. The ratio between Sm(3+) emission and TiO2 trap emission shows strong temperature dependence, and is tested for temperature sensing. The relative sensor sensitivity was found to be higher than 1% °C(-1) over given temperature range with the maximum value of 10.54% °C(-1) at 57.5 °C. Lifetime data derived from the Sm(3+) emission decay revealed that time-resolved measurements provide comparable quality of temperature sensing as corresponding ratiometric measurements, with a maximum relative sensitivity of 10.14% °C(-1) at 66.5 °C.

Thermographic properties of Sm3+-doped GdVO4 phosphor

Rare-earth orthovanadates are important hosts for the luminescence of rare earth activators with considerable practical applications in the artificial production of light. In this paper we investigated the possibility for GdVO4:Sm3+ usage in phosphor thermometry by observing the temperature changes of trivalent samarium transitions from 4F3/2 and 4G5/2 energy levels to the ground state. A set of three samples of Sm3+-doped GdVO4 (0.5, 1 and 2 mol.% Sm3+ with respect to Gd3+ ions) was produced via solid state synthesis. The sample crystalline structure is confirmed from x-ray diffraction (XRD) measurements. Photoluminescence measurements were recorded in the temperature range 293–823 K and the fluorescence intensity ratio of the paired emissions bands was studied as a function of temperature. All three GdVO4:Sm3+ samples proved to have good potential for the development of thermographic phosphors, whereas the maximum sensitivity of approximately 4.5×10-4 K−1 was found for the sample with 2 mol.% Sm3+ in the temperature region around 750 K.

PMMA/Zn 2 SiO 4 :Eu 3+ (Mn 2+ ) Composites: Preparation, Optical, and Thermal Properties

Luminescent composites of poly(methylmethacrylate) (PMMA) and nanophosphors (Zn2SiO4:Mn2+, Zn2SiO4:Eu3+) were prepared by dispersion casting method. It was found that nanoparticles embedded in PMMA matrix preserve their typical phosphorescence emission. The influence of Zn2SiO4 nanofillers on thermal properties of PMMA was also investigated. A shift towards higher glass transition temperatures and slight improvements in thermal stability of the nanocomposites compared to pure PMMA were observed and are discussed herein.

Structural and optical investigation of gadolinia-doped ceria powders prepared by polymer complex solution method

Abstract We present a polymer complex solution method using a modified combustion synthesis procedure, for the production of well crystalline, sub-micron gadolinia-doped ceria powders of Ce0.9Gd0.1O1.95 composition. Polyethylene glycol of two different molecular weights (200 and 20000) was used as both fuel for the combustion and nucleating agent for the crystallization process. The synthesized materials were characterized using X-ray diffraction, thermal analysis, scanning electron microscopy, and optical and photoluminescence spectroscopy. The powders are quite similar, fully crystallized in a cubic fluorite-type phase with average crystallite size of about 70 nm and average particle size in the range 220–240 nm. UV-vis absorption spectra show the absorption edge at 3.26 eV. The presence of oxygen vacancies, confirmed indirectly by clear violet emission observed at 428 nm, originated from the 5D1 → 4F1 transition of Ce3+ions.

Processing and characterization of up-converting Er3+ doped (Lu0.5Y0.5)2O3 nanophosphor

Abstract In this paper we demonstrate visible up-conversion emission of Er3+ doped (Lu0.5Y0.5)2O3 nanophosphor and discuss possible mechanisms for pumping the upper energy levels of Er3+ ions. Polymer complex solution synthesis yields well crystalline, pure-phase cubic nanopowder with particle size in the 20–50 nm range. Red, green and blue up-conversion emission is measured under near-infrared excitation (1 540 nm), over the temperature range 10–300 K. The red/green intensity ratio indicates that the mechanism responsible for populating red up-conversion is temperature dependent. Decay times are found to be around 0.25 ms for red and green, and around 70 μs for blue emission.

Sol-Gel Derived Eu3+-Doped Gd2Ti2O7Pyrochlore Nanopowders

Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (∼2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (~2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.

Sol-Gel derived Eu 3+ -doped Gd 2 Ti 2 O 7 pyrochlore nanopowders

Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (∼2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (~2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.

Sol-Gel Derived Eu3

Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (∼2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (~2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.

ICOM2012: 3rd International Conference on the Physics of Optical Materials and Devices (Belgrade, Serbia, 2–6 September 2012)

The 3rd International Conference on the Physics of Optical Materials and Devices (ICOM2012) was held in Belgrade (Serbia) from 2 to 6 September 2012 (figure 1). The conference was organized by the Vinca Institute of Nuclear Sciences, University of Belgrade (Serbia) and the Laboratoire de Chimie de la Matiere Condensee de Paris (France), and supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia and Optical Society of America. ICOM2012 was a follow-up to the two previous, successful ICOM conferences held in Herceg Novi in 2006 and 2009. The conference aimed at providing a forum for scientists in optical materials to debate on: • Luminescent materials and nanomaterials• Hybrid optical materials (organic/inorganic)• Characterization techniques of optical materials• Luminescence mechanisms and energy transfers• Theory and modeling of optical processes• Ultrafast-laser processing of materials• Optical sensors• Medical imaging• Advanced optical materials in photovoltaics and biophotonics• Photothermal and photoacoustic spectroscopy and phenomena The conference stressed the value of a fundamental scientific understanding of optical materials. A particular accent was put on wide band-gap materials in crystalline, glass and nanocrystalline forms. The applications mainly involved lasers, scintillators and phosphors. Rare earth and transition metal ions introduced as dopants in various hosts were considered, and their impact on the optical properties were detailed in several presentations. This volume contains selected contributions of speakers and participants of the ICOM2012 conference. The conference provided a unique opportunity for about 200 scientists from 32 countries to discuss recent progress in the field of optical materials. During the three and half days, 21 invited talks and 52 contributed lectures were given, with a special event in memory of our dear colleague Professor Dr Tsoltan Basiev (Russia). In addition, 183 posters were presented and the two Young Scientist Awards were announced at the closing ceremony. Acknowledgments We thank all the authors for their valuable research contribution presented in this volume. We express our acknowledgements to all reviewers with a special thanks to Dr G Watt, then Publisher of the journal, for accepting the publication of these papers in a special issue of Physica Scripta . We wish to express our gratitude to the members of the ICOM scientific advisory committee and organizing committee for their excellent work and commitment for the success of ICOM2012.

Structural and optical properties of europium doped Y2O3 nanoparticles prepared by self-propagation room temperature reaction method

Abstract Europium-doped yttrium oxide nanoparticles with different doping concentrations were prepared by self-propagation room temperature reaction method. This simple synthesis method provides particles in the range of 12nm to 50 nm, depending on the temperature of calcination. In all cases, the nanopowders showed intense red emission upon excitation with ultraviolet radiation. Structural and optical characterization showed that the nanoparticles obtained after calcination at 1100°C have smaller unit cell volume and microstrain and longer emission lifetimes compared to the nanoparticles obtained after calcination at 600°C and 800°C. The maximal emission intensity was found for the sample doped with 5at% of Eu3+.