The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Christophe Dujardin - One of the best experts on this subject based on the ideXlab platform.
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Perfectly Transparent Sr3Al2O6 Polycrystalline Ceramic Elaborated from Glass Crystallization
Chemistry of Materials, 2013Co-Authors: Salaheddine Alahrache, Kholoud Al Saghir, Sébastien Chenu, Emmanuel Véron, Domingos De Sousa Meneses, Ana Isabel Becerro, Manuel Ocaña, F. Moretti, Gaël Patton, Christophe DujardinAbstract:International audienceThe highly visible and infrared (up to 6 mu m) transparent Sr3Al2O6 Polycrystalline Ceramic was obtained by full crystallization of the corresponding glass composition. The glass synthesis and the direct congruent crystallization processes are described, and the material transparency is discussed in light of its microstructure. This new transparent Ceramic exhibits a high density (i.e., complete absence of porosity) and micrometer-scale crystallites with very thin grain boundaries. These microstructural characteristics, inherent to the preparation method, minimize light scattering and demonstrate the advantages of this synthesis route compared to the high-pressure process used for the few reported transparent Polycrystalline materials. This Sr3Al2O6 Ceramic shows a H = 10.5 GPa hardness, a E-r = 150 GPa reduced elasticity modulus, and a 9.6 x 10(-6) K-1 thermal expansion coefficient. Such a transparent strontium aluminate Ceramic opens the way to a wide range of applications, especially photonics when doped by various doping agents. As examples, the luminescence of Sr3Al2O6:Eu3+ and Sr3Al2O6:Er3+, which show strong emissions in the visible and infrared ranges, respectively, is presented. Moreover, the Sr3Al2O6:Ce3+ material was found to exhibit scintillation properties under X-ray excitation. Interestingly, the analogous Sr3Ga2O6 transparent Polycrystalline Ceramic material could equally be prepared using the same elaboration method, although its hygroscopicity prevents the preservation of its high transparency under normal conditions. The establishment of the key factors for the transparency of this economical and innovative synthesis method should enable the prediction of new classes of technologically relevant transparent Ceramics
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Perfectly Transparent Sr3Al2O6 Polycrystalline Ceramic Elaborated from Glass Crystallization
Chemistry of Materials, 2013Co-Authors: Salaheddine Alahrache, Sébastien Chenu, Emmanuel Véron, Ana Isabel Becerro, Manuel Ocaña, F. Moretti, Gaël Patton, Kholoud Al Saghir, Domingos De Sousa Meneses, Christophe DujardinAbstract:The highly visible and infrared (up to 6 mu m) transparent Sr3Al2O6 Polycrystalline Ceramic was obtained by full crystallization of the corresponding glass composition. The glass synthesis and the direct congruent crystallization processes are described, and the material transparency is discussed in light of its microstructure. This new transparent Ceramic exhibits a high density (i.e., complete absence of porosity) and micrometer-scale crystallites with very thin grain boundaries. These microstructural characteristics, inherent to the preparation method, minimize light scattering and demonstrate the advantages of this synthesis route compared to the high-pressure process used for the few reported transparent Polycrystalline materials. This Sr3Al2O6 Ceramic shows a H = 10.5 GPa hardness, a E-r = 150 GPa reduced elasticity modulus, and a 9.6 x 10(-6) K-1 thermal expansion coefficient. Such a transparent strontium aluminate Ceramic opens the way to a wide range of applications, especially photonics when doped by various doping agents. As examples, the luminescence of Sr3Al2O6:Eu3+ and Sr3Al2O6:Er3+, which show strong emissions in the visible and infrared ranges, respectively, is presented. Moreover, the Sr3Al2O6:Ce3+ material was found to exhibit scintillation properties under X-ray excitation. Interestingly, the analogous Sr3Ga2O6 transparent Polycrystalline Ceramic material could equally be prepared using the same elaboration method, although its hygroscopicity prevents the preservation of its high transparency under normal conditions. The establishment of the key factors for the transparency of this economical and innovative synthesis method should enable the prediction of new classes of technologically relevant transparent Ceramics.
John B Gruber - One of the best experts on this subject based on the ideXlab platform.
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comparative study of the crystal field splitting of trivalent neodymium energy levels in Polycrystalline Ceramic and nanocrystalline yttrium oxide
Journal of Applied Physics, 2007Co-Authors: John B Gruber, Dhiraj K Sardar, Kelly L Nash, Raylon M. YowAbstract:Absorption and fluorescence spectra of commercially available Polycrystalline Ceramic Nd3+:Y2O3 and nanocrystalline aggregates of Nd3+:Y2O3 grown in our laboratory are optically characterized at nominal 8K and room temperature. In comparing the spectra obtained from these two different sources, we find similarities in terms of the detailed crystal-field splitting of the energy levels of the Nd3+ ion in the Y2O3 host. The 8K spectra are analyzed for the energy (Stark) level transitions between the LJ2S+1 multiplet manifolds of Nd3+(4f3). The analysis includes the manifolds of I9∕24 (the ground state), I11∕24, I13∕24, I15∕24, F3∕24, F5∕24, H9∕22, F7∕24, S3∕24, and F9∕24. The results of this study are also compared with a crystal-field splitting analysis reported earlier for single-crystal Nd3+:Y2O3 grown by a modified flame fusion method. We find that the spectroscopic properties of our composites compare favorably with other Ceramic and single-crystal forms of Nd3+:Y2O3 currently available.
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Optical absorption intensity analysis and emission cross sections for the intermanifold and the inter-Stark transitions of Nd3+(4f3) in Polycrystalline Ceramic Y2O3
Journal of Applied Physics, 2006Co-Authors: Dhiraj K Sardar, Raylon M. Yow, Kelly L Nash, Douglas M. Dee, John B GruberAbstract:Spectroscopic properties have been characterized for trivalent neodymium doped Polycrystalline Ceramic ytttria, Nd3+:Y2O3. The Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] analysis has been applied to the room temperature absorption spectrum to determine the radiative decay rates and branching ratios of Nd3+ transitions from the F3∕24 metastable manifold to the IJ4 lower-lying multiplet manifolds. The quantum efficiency is determined from the measured fluorescence lifetime and the radiative lifetime of the F3∕24 manifold state. In addition, a detailed characterization of the Stark energy levels of the I9∕24 and I11∕24 manifolds has been performed using the room temperature fluorescence spectra for the F3∕24→I9∕24 and F3∕24→I11∕24 transitions of Nd3+(4f3) in Ceramic Y2O3. The emission cross sections of the F3∕24→I9∕24 and F3∕24→I11∕24 intermanifold transitions have been determined. Also, the peak emission cross sections of the principal inter-Stark peak transitions R1→X5 and R1→Y2...
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Stark components of lower-lying manifolds and emission cross-sections of intermanifold and inter-stark transitions of Nd3+(4f3) in Polycrystalline Ceramic garnet Y3Al5O12
Journal of Luminescence, 2005Co-Authors: Dhiraj K Sardar, John B Gruber, Toomas H Allik, Raylon M. Yow, Bahram ZandiAbstract:Abstract Stark energy levels of the 4 F 3/2 , 4 I 9/2 , and 4 I 11/2 manifolds have been characterized using the room temperature fluorescence spectra for the 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 transitions of Nd 3+ (4f 3 ) in Polycrystalline Ceramic garnet Y 3 Al 5 O 12 (YAG). The emission cross-sections of the intermanifold transitions, 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 , as well as the principal inter-Stark transitions, R 1 →Z 5 (945.3 nm) and R 1 →Y 2 (1063.5 nm), have also been determined. These results are finally compared with those of Nd 3+ :YAG single crystal.
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absorption intensities and emission cross sections of principal intermanifold and inter stark transitions of er3 4f11 in Polycrystalline Ceramic garnet y3al5o12
Journal of Applied Physics, 2005Co-Authors: Dhiraj K Sardar, Charles C Russell, John B Gruber, Toomas H AllikAbstract:A comparative spectroscopic study is performed on Er3+(4f11) ions doped in Polycrystalline Ceramic garnet Y3Al5O12 (YAG) and single-crystal laser rod, both containing nominal 50 at. % of Er3+. The standard Judd–Ofelt (JO) model is applied to the room-temperature absorption intensities of Er3+(4f11) transitions in both hosts to obtain the phenomenological intensity parameters. These parameters are subsequently used to determine the radiative decay rates, radiative lifetimes, and branching ratios of the Er3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds LJ2S+1 of Er3+(4f11) in these garnet hosts. The emission cross sections of the intermanifold Er3+I13∕24→I15∕24 (1.5 μm) transition as well as the principal inter-Stark transition Y1→Z4 (1550 nm) within the corresponding multiplet manifolds have been determined. The room-temperature fluorescence lifetimes of the I13∕24→I15∕24 (1.5 μm) transition in both Polycrystalline Ceramic and single-crystal YAG sample...
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Spectral analysis and energy-level structure of Er3+(4f11) in Polycrystalline Ceramic garnet Y3Al5O12
Journal of Applied Physics, 2005Co-Authors: John B Gruber, Dhiraj K Sardar, Charles C Russell, Toomas H Allik, Anmol S. Nijjar, Raylon M. Yow, Bahram ZandiAbstract:Absorption spectra obtained between 1550 and 440nm and fluorescence spectra obtained between 1700 and 1500nm are reported in a comparative spectroscopic study of Polycrystalline Ceramic Y3Al5O12 (YAG) and single-crystal laser rod YAG, both containing 50at.% Er3+ as a dopant in the garnet host. The spectra are observed in both samples at temperatures between 8K and room temperature. The detailed splitting of individual multiplet manifolds, LJ2S+1, Er3+(4f11), by the crystalline electric field is similar in both the Ceramic sample and the single-crystal laser rod. With few exceptions, there is little shift in energy (few wave numbers) of individual Stark levels within a manifold, between dilute and concentrated Er3+ samples. This is not too surprising since Y3Al5O12 and Er3Al5O12 form a solid solution with the majority of Er3+ ions occupying cation sites having D2 symmetry in the garnet lattice over the entire solid solution range. As a check on the observed manifold splittings of Er3+ in Ceramic YAG, we co...
S. N. Dolia - One of the best experts on this subject based on the ideXlab platform.
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effect of thermal history on structural microstructural properties and j e characteristics of cacu3ti4o12 Polycrystalline Ceramic
Materials Chemistry and Physics, 2018Co-Authors: P.y. Raval, A.r. Makadiya, P.r. Pansara, Poornima Sharma, N. H. Vasoya, J. A. Bhalodia, Sudhish Kumar, S. N. DoliaAbstract:Abstract We report, the effect of heat treatments slow cooling, rapid thermal cooling (quenching) and microwave-assisted heating, on structural, microstructural and J – E characteristics of CaCu 3 Ti 4 O 12 Polycrystalline Ceramic. Rietveld refinement of X-ray data confirms the emergence of the mono-phasic cubic perovskite structure, diffraction line broadening and change in the relative intensity of diffraction peaks while scanning electron microscopy revealed completely different grain morphology. The observed modifications have been discussed in detail. The strong nonlinear J – E characteristics over the wide temperature range (300–823 K) indicated the existence of a Schottky-type electrostatic potential barrier at the grain boundaries. The parameters, nonlinear coefficient, threshold electric field, potential barrier height suggest suitability of the materials for low voltage varistor applications.
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Effect of thermal history on structural, microstructural properties and J – E characteristics of CaCu3Ti4O12 Polycrystalline Ceramic
Materials Chemistry and Physics, 2018Co-Authors: P.y. Raval, A.r. Makadiya, P.r. Pansara, Poornima Sharma, N. H. Vasoya, J. A. Bhalodia, Sudhish Kumar, S. N. Dolia, Kunal B. ModiAbstract:Abstract We report, the effect of heat treatments slow cooling, rapid thermal cooling (quenching) and microwave-assisted heating, on structural, microstructural and J – E characteristics of CaCu 3 Ti 4 O 12 Polycrystalline Ceramic. Rietveld refinement of X-ray data confirms the emergence of the mono-phasic cubic perovskite structure, diffraction line broadening and change in the relative intensity of diffraction peaks while scanning electron microscopy revealed completely different grain morphology. The observed modifications have been discussed in detail. The strong nonlinear J – E characteristics over the wide temperature range (300–823 K) indicated the existence of a Schottky-type electrostatic potential barrier at the grain boundaries. The parameters, nonlinear coefficient, threshold electric field, potential barrier height suggest suitability of the materials for low voltage varistor applications.
Dhiraj K Sardar - One of the best experts on this subject based on the ideXlab platform.
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comparative study of the crystal field splitting of trivalent neodymium energy levels in Polycrystalline Ceramic and nanocrystalline yttrium oxide
Journal of Applied Physics, 2007Co-Authors: John B Gruber, Dhiraj K Sardar, Kelly L Nash, Raylon M. YowAbstract:Absorption and fluorescence spectra of commercially available Polycrystalline Ceramic Nd3+:Y2O3 and nanocrystalline aggregates of Nd3+:Y2O3 grown in our laboratory are optically characterized at nominal 8K and room temperature. In comparing the spectra obtained from these two different sources, we find similarities in terms of the detailed crystal-field splitting of the energy levels of the Nd3+ ion in the Y2O3 host. The 8K spectra are analyzed for the energy (Stark) level transitions between the LJ2S+1 multiplet manifolds of Nd3+(4f3). The analysis includes the manifolds of I9∕24 (the ground state), I11∕24, I13∕24, I15∕24, F3∕24, F5∕24, H9∕22, F7∕24, S3∕24, and F9∕24. The results of this study are also compared with a crystal-field splitting analysis reported earlier for single-crystal Nd3+:Y2O3 grown by a modified flame fusion method. We find that the spectroscopic properties of our composites compare favorably with other Ceramic and single-crystal forms of Nd3+:Y2O3 currently available.
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Optical absorption intensity analysis and emission cross sections for the intermanifold and the inter-Stark transitions of Nd3+(4f3) in Polycrystalline Ceramic Y2O3
Journal of Applied Physics, 2006Co-Authors: Dhiraj K Sardar, Raylon M. Yow, Kelly L Nash, Douglas M. Dee, John B GruberAbstract:Spectroscopic properties have been characterized for trivalent neodymium doped Polycrystalline Ceramic ytttria, Nd3+:Y2O3. The Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] analysis has been applied to the room temperature absorption spectrum to determine the radiative decay rates and branching ratios of Nd3+ transitions from the F3∕24 metastable manifold to the IJ4 lower-lying multiplet manifolds. The quantum efficiency is determined from the measured fluorescence lifetime and the radiative lifetime of the F3∕24 manifold state. In addition, a detailed characterization of the Stark energy levels of the I9∕24 and I11∕24 manifolds has been performed using the room temperature fluorescence spectra for the F3∕24→I9∕24 and F3∕24→I11∕24 transitions of Nd3+(4f3) in Ceramic Y2O3. The emission cross sections of the F3∕24→I9∕24 and F3∕24→I11∕24 intermanifold transitions have been determined. Also, the peak emission cross sections of the principal inter-Stark peak transitions R1→X5 and R1→Y2...
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Stark components of lower-lying manifolds and emission cross-sections of intermanifold and inter-stark transitions of Nd3+(4f3) in Polycrystalline Ceramic garnet Y3Al5O12
Journal of Luminescence, 2005Co-Authors: Dhiraj K Sardar, John B Gruber, Toomas H Allik, Raylon M. Yow, Bahram ZandiAbstract:Abstract Stark energy levels of the 4 F 3/2 , 4 I 9/2 , and 4 I 11/2 manifolds have been characterized using the room temperature fluorescence spectra for the 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 transitions of Nd 3+ (4f 3 ) in Polycrystalline Ceramic garnet Y 3 Al 5 O 12 (YAG). The emission cross-sections of the intermanifold transitions, 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 , as well as the principal inter-Stark transitions, R 1 →Z 5 (945.3 nm) and R 1 →Y 2 (1063.5 nm), have also been determined. These results are finally compared with those of Nd 3+ :YAG single crystal.
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absorption intensities and emission cross sections of principal intermanifold and inter stark transitions of er3 4f11 in Polycrystalline Ceramic garnet y3al5o12
Journal of Applied Physics, 2005Co-Authors: Dhiraj K Sardar, Charles C Russell, John B Gruber, Toomas H AllikAbstract:A comparative spectroscopic study is performed on Er3+(4f11) ions doped in Polycrystalline Ceramic garnet Y3Al5O12 (YAG) and single-crystal laser rod, both containing nominal 50 at. % of Er3+. The standard Judd–Ofelt (JO) model is applied to the room-temperature absorption intensities of Er3+(4f11) transitions in both hosts to obtain the phenomenological intensity parameters. These parameters are subsequently used to determine the radiative decay rates, radiative lifetimes, and branching ratios of the Er3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds LJ2S+1 of Er3+(4f11) in these garnet hosts. The emission cross sections of the intermanifold Er3+I13∕24→I15∕24 (1.5 μm) transition as well as the principal inter-Stark transition Y1→Z4 (1550 nm) within the corresponding multiplet manifolds have been determined. The room-temperature fluorescence lifetimes of the I13∕24→I15∕24 (1.5 μm) transition in both Polycrystalline Ceramic and single-crystal YAG sample...
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Spectral analysis and energy-level structure of Er3+(4f11) in Polycrystalline Ceramic garnet Y3Al5O12
Journal of Applied Physics, 2005Co-Authors: John B Gruber, Dhiraj K Sardar, Charles C Russell, Toomas H Allik, Anmol S. Nijjar, Raylon M. Yow, Bahram ZandiAbstract:Absorption spectra obtained between 1550 and 440nm and fluorescence spectra obtained between 1700 and 1500nm are reported in a comparative spectroscopic study of Polycrystalline Ceramic Y3Al5O12 (YAG) and single-crystal laser rod YAG, both containing 50at.% Er3+ as a dopant in the garnet host. The spectra are observed in both samples at temperatures between 8K and room temperature. The detailed splitting of individual multiplet manifolds, LJ2S+1, Er3+(4f11), by the crystalline electric field is similar in both the Ceramic sample and the single-crystal laser rod. With few exceptions, there is little shift in energy (few wave numbers) of individual Stark levels within a manifold, between dilute and concentrated Er3+ samples. This is not too surprising since Y3Al5O12 and Er3Al5O12 form a solid solution with the majority of Er3+ ions occupying cation sites having D2 symmetry in the garnet lattice over the entire solid solution range. As a check on the observed manifold splittings of Er3+ in Ceramic YAG, we co...
Jian Zhang - One of the best experts on this subject based on the ideXlab platform.
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Continuous-wave and Q-switched operation of a resonantly pumped Polycrystalline Ceramic Ho:LuAG laser
Optics express, 2014Co-Authors: Ting Zhao, Deyuan Shen, Dingyuan Tang, Jian Zhang, Yong Wang, Hao ChenAbstract:We have reported continuous-wave (CW) and Q-switched operations of a Polycrystalline Ceramic Ho:LuAG laser in band pumped by a Tm:fiber laser at the wavelength of 1907 nm. By using an output coupler of 20% transmission, maximum continuous-wave output power of 2.87 W for 9.72 W of incident pump power was achieved, corresponding to a slope efficiency of 31.9%. Shortest pulse duration of 21.0 ns with peak power of 28.2 kW has been obtained at 500 Hz pulse repetition frequency (PRF) under 5.65 W of incident pump power.
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widely tunable narrow bandwidth Polycrystalline Ceramic er yag laser with a volume bragg grating
Optics Express, 2014Co-Authors: Xiaoqi Zhang, Deyuan Shen, Dingyuan Tang, Hai Tao Huang, Jun Liu, Xuan Liu, Jianing Zhang, Jian Zhang, Dianyuan FanAbstract:We report on a tunable Polycrystalline Ceramic Er:YAG laser with a total tuning range of 23.1 nm by using a volume Bragg grating. The whole tuning range was composed of three parts, 1614.2 nm - 1621.5 nm, 1629.3 nm - 1635.1 nm and 1639.2 nm - 1649.2 nm. The bandwidth of the output spectrum (FWHM) of the tunable Er:YAG laser was narrowed down to <0.05 nm over the whole tuning range. To our knowledge, this is the widest tuning range so far in this material and it is the first time to report an Er:YAG laser operating at around 1630 nm. In the tuning range of 1629.3 nm- 1635.1 nm, the maximum output power of 1.4 W was obtained at 1633.0 nm with a slope efficiency of 20.9% with respect to the incident power.
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Widely tunable, narrow bandwidth Polycrystalline Ceramic Er:YAG laser with a volume Bragg grating.
Optics express, 2014Co-Authors: Xiaoqi Zhang, Deyuan Shen, Dingyuan Tang, Hai Tao Huang, Jun Liu, Xuan Liu, Jianing Zhang, Jian Zhang, Dianyuan FanAbstract:We report on a tunable Polycrystalline Ceramic Er:YAG laser with a total tuning range of 23.1 nm by using a volume Bragg grating. The whole tuning range was composed of three parts, 1614.2 nm - 1621.5 nm, 1629.3 nm - 1635.1 nm and 1639.2 nm - 1649.2 nm. The bandwidth of the output spectrum (FWHM) of the tunable Er:YAG laser was narrowed down to
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Polycrystalline Ceramic Er:YAG Laser In-Band Pumped by a High-Power Er,Yb Fiber Laser at 1532 nm
Applied Physics Express, 2011Co-Authors: D.y. Shen, Dingyuan Tang, Jian Zhang, Hao Chen, Xiangpeng Qin, Xiaofang Yang, Ting ZhaoAbstract:We report on the high-power and efficient operation of a Polycrystalline Ceramic erbium-doped yttrium aluminum garnet (Er:Y3Al5O12, Er:YAG) laser resonantly pumped by a cladding-pumped Er,Yb fiber laser. The pump fiber laser was wavelength-locked to the absorption peak of Er:YAG at ~1532 nm using a volume Bragg grating. The Ceramic laser yielded 13.8 W of continuous-wave output at 1645 nm for 27.3 W of incident pump power, corresponding to a slope efficiency of 54.5% with respect to the incident pump power. The laser output characteristics of different Er3+ doping levels are compared, and the prospects for improvement in lasing efficiency and output power are discussed.