The structural and spectroscopic properties of Na2O-Al2O3-SiO2-xP2O5 glasses （x = 0 to 7 mol%） are investigated. Both Raman and IR spectra reveal that discrete phosphate species （[PO4]-3, [PO3O1/2]-2） with low pol...The structural and spectroscopic properties of Na2O-Al2O3-SiO2-xP2O5 glasses （x = 0 to 7 mol%） are investigated. Both Raman and IR spectra reveal that discrete phosphate species （[PO4]-3, [PO3O1/2]-2） with low polymerization degree can be formed in the silicate glass. These phosphate structures scavenge non-bridging oxygen ions and cations from the silicate network, resulting in an increase of the glass transi- tion temperature. According to the Judd-Ofelt intensity parameters （Ω2,Ω4, Ω6） of Er3＋, the asymmetry of local environment around Er3＋ becomes higher, and the bond covalency between Er3＋ and O2-decreases after P2O5 is introduced. In the emission spectra, photoluminescence intensity increases with increasing P2O5 concentration and the spectra are inhomogeneously broadened, revealing that the ligand electric field around Er3＋ is dramatically changed, and the glass matrix becomes disordered.展开更多
Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spect...Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy. The absorption, emission spectra and fluorescence decay studies were carried out both at low and room temperatures. Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass. Up-conversion and cooperative fluorescence were also discussed.展开更多
Yb-Er codoped Na2O-Al2O3-P2O5-xSiO2 glasses containing 0 - 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between pS＋ and non-bridging oxygen but also...Yb-Er codoped Na2O-Al2O3-P2O5-xSiO2 glasses containing 0 - 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between pS＋ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4＋, most probably there coexist [SiO4] tetrahedron and [SiO6] oetahedron in our glasses. Within the range of 0 - 20 mol% SiO2 addition, the stimulated emission cross-section of Era＋ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3＋, Ω2 does not change greatly, but Ω4 and Ω6 decrease obviously with increasing SiO2 addition, because the bond between Er3＋ and O2- is more strongly eovalently bonded.展开更多
The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic par...The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.展开更多
Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scin...Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields. In both cases, the rare earth ions are playing the crucial role as emission centers. Pr^3＋ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce^3＋. Among several candidate hosts, LuAG showed the best performance. Bulk crystal growth, basic scintillation properties, two-dimensional gamma-ray imaging and positron emission mammography （PEM） application were demonstrated. Due to the international situation, the homeland security was compromized by illicit traffic of explosives, drugs, nuclear materials, etc. and the ways to its improvement became an important R＆D topic. For this purpose the Ce and Eu doped LiCAF appeared competitive candidates. Especially, when substitution of 3He neutron detectors was considered, the discrimination ability of gamma-ray from alpha-ray was important. Bulk crystal growth, basic scintillation properties and two-dimensional neutron imaging were demonstrated.展开更多
文摘The structural and spectroscopic properties of Na2O-Al2O3-SiO2-xP2O5 glasses （x = 0 to 7 mol%） are investigated. Both Raman and IR spectra reveal that discrete phosphate species （[PO4]-3, [PO3O1/2]-2） with low polymerization degree can be formed in the silicate glass. These phosphate structures scavenge non-bridging oxygen ions and cations from the silicate network, resulting in an increase of the glass transi- tion temperature. According to the Judd-Ofelt intensity parameters （Ω2,Ω4, Ω6） of Er3＋, the asymmetry of local environment around Er3＋ becomes higher, and the bond covalency between Er3＋ and O2-decreases after P2O5 is introduced. In the emission spectra, photoluminescence intensity increases with increasing P2O5 concentration and the spectra are inhomogeneously broadened, revealing that the ligand electric field around Er3＋ is dramatically changed, and the glass matrix becomes disordered.
文摘Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy. The absorption, emission spectra and fluorescence decay studies were carried out both at low and room temperatures. Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass. Up-conversion and cooperative fluorescence were also discussed.
基金supported by the International Cooperation Project of Shanghai Municipal Science Technology Commission under Grant No.05S207103.
文摘Yb-Er codoped Na2O-Al2O3-P2O5-xSiO2 glasses containing 0 - 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between pS＋ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4＋, most probably there coexist [SiO4] tetrahedron and [SiO6] oetahedron in our glasses. Within the range of 0 - 20 mol% SiO2 addition, the stimulated emission cross-section of Era＋ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3＋, Ω2 does not change greatly, but Ω4 and Ω6 decrease obviously with increasing SiO2 addition, because the bond between Er3＋ and O2- is more strongly eovalently bonded.
基金supported by the International Cooperation Project of Shanghai Municipal Science and Technology Commission under Grant No.05S207103.
文摘The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.
基金Project supported by Japan Science and Technology Agency,Regional Research and Development Resources Utilization Program,Ministry of Education,Culture,Sports,Science and Technology of Japanese government,Grant-in-Aid for Young Scientists (A)the joint project between JSPS and ASCR (19686001 (AY))+2 种基金Czech GAAV Project (M100100910)the Funding Program for Next Generation World-Leading ResearchersJapan Society for Promotion of Science
文摘Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields. In both cases, the rare earth ions are playing the crucial role as emission centers. Pr^3＋ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce^3＋. Among several candidate hosts, LuAG showed the best performance. Bulk crystal growth, basic scintillation properties, two-dimensional gamma-ray imaging and positron emission mammography （PEM） application were demonstrated. Due to the international situation, the homeland security was compromized by illicit traffic of explosives, drugs, nuclear materials, etc. and the ways to its improvement became an important R＆D topic. For this purpose the Ce and Eu doped LiCAF appeared competitive candidates. Especially, when substitution of 3He neutron detectors was considered, the discrimination ability of gamma-ray from alpha-ray was important. Bulk crystal growth, basic scintillation properties and two-dimensional neutron imaging were demonstrated.
