The electronic structure and electronic absorption spectra of binuclear Au(Ⅰ) complexes with bidentate phophines and a bidentate ylid ligand have been studied using quasirelativistic pseudopotential ab initio cal...The electronic structure and electronic absorption spectra of binuclear Au(Ⅰ) complexes with bidentate phophines and a bidentate ylid ligand have been studied using quasirelativistic pseudopotential ab initio calculations at the HF and MP2 levels by the LANL2DZ basis sets. The electronic properties of the spectral transition and Au(Ⅰ)—Au(Ⅰ) interaction were also discussed.展开更多
The green-emitting phosphor BaSi2O5 ：Eu^2＋ was synthesized by the conventional solid state reaction. Using the CASTEP code, BaSi2O5 is calculated to be an intermediate band gap semiconductor with an indirect energy ...The green-emitting phosphor BaSi2O5 ：Eu^2＋ was synthesized by the conventional solid state reaction. Using the CASTEP code, BaSi2O5 is calculated to be an intermediate band gap semiconductor with an indirect energy gap of about 3.2 eV. As expected, the calculated optical band gap of BaSi2O5 is lower compared to the experimentally determined values. Eu^2＋-activated BaSi2O5 phosphor can be excited efficiently over a broad spectral range between 200 and 400 nm, and has an emission peak at 500 nm with a full width at half maximum of 95 nm. The study of concentration-dependent emission intensity shows the optimal concentration of the Eu^2＋ is 0.05 mol, and that concentration quenching occurs when the Eu^2＋ content is beyond the critical value. The external quantum efficiency of the optimized BaSi2O5 ：Eu^2＋ is 96. 1%, 70.2% and 62.1% under excitation at 315,350 and 365 nm, respectively. The superior optical properties of the sample show the potential as an ultraviolet converting green-emitting phosphor for white light emitting diodes.展开更多
Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2 CO3 and NH4 Cl were used as the fluxes.The phase for...Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2 CO3 and NH4 Cl were used as the fluxes.The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photo luminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi2 O2 N2：Eu^2＋ phosphor can be improved effectively. The photoluminescence intensity of BaSi2 O2 N2：Eu^2＋ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2 CO3, NH4 Cl and without flux. The optimum content of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2 O2 N2：Eu^2＋ phosphor prepared with BaF2 flux rises to 141%,meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2 O2 N2：Eu^2＋ is sort of promising bluish-green phosphor for application in full-spectra LED.展开更多
文摘The electronic structure and electronic absorption spectra of binuclear Au(Ⅰ) complexes with bidentate phophines and a bidentate ylid ligand have been studied using quasirelativistic pseudopotential ab initio calculations at the HF and MP2 levels by the LANL2DZ basis sets. The electronic properties of the spectral transition and Au(Ⅰ)—Au(Ⅰ) interaction were also discussed.
文摘The green-emitting phosphor BaSi2O5 ：Eu^2＋ was synthesized by the conventional solid state reaction. Using the CASTEP code, BaSi2O5 is calculated to be an intermediate band gap semiconductor with an indirect energy gap of about 3.2 eV. As expected, the calculated optical band gap of BaSi2O5 is lower compared to the experimentally determined values. Eu^2＋-activated BaSi2O5 phosphor can be excited efficiently over a broad spectral range between 200 and 400 nm, and has an emission peak at 500 nm with a full width at half maximum of 95 nm. The study of concentration-dependent emission intensity shows the optimal concentration of the Eu^2＋ is 0.05 mol, and that concentration quenching occurs when the Eu^2＋ content is beyond the critical value. The external quantum efficiency of the optimized BaSi2O5 ：Eu^2＋ is 96. 1%, 70.2% and 62.1% under excitation at 315,350 and 365 nm, respectively. The superior optical properties of the sample show the potential as an ultraviolet converting green-emitting phosphor for white light emitting diodes.
基金Project supported by the National Key Research and Development Program of China(2016YFB0701003)
文摘Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2 CO3 and NH4 Cl were used as the fluxes.The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photo luminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi2 O2 N2：Eu^2＋ phosphor can be improved effectively. The photoluminescence intensity of BaSi2 O2 N2：Eu^2＋ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2 CO3, NH4 Cl and without flux. The optimum content of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2 O2 N2：Eu^2＋ phosphor prepared with BaF2 flux rises to 141%,meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2 O2 N2：Eu^2＋ is sort of promising bluish-green phosphor for application in full-spectra LED.
