Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In...Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3＋ centers in Ca3Sc2Si3O12 by considering the effects of the charge com- pensations related to N3-, Sc3＋, Mn2＋, Mg2＋, and Na＋. Firstly, the local structures around Ce3＋ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce3＋ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3＋-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3＋ substituting Si4＋. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.展开更多
Synthesis of oxynitride solid solutions CaAl4-xSixO7-xNx:Eu2+ (x = 0 - 4) was attempted by the solid state reaction (SSR) methods using Si3N4 and AlN as nitrogen sources. The Ca3Al8Si4O17N4 (x = 4/3) sample with the h...Synthesis of oxynitride solid solutions CaAl4-xSixO7-xNx:Eu2+ (x = 0 - 4) was attempted by the solid state reaction (SSR) methods using Si3N4 and AlN as nitrogen sources. The Ca3Al8Si4O17N4 (x = 4/3) sample with the high phase purity was obtained when AlN was used as a nitrogen source whereas the sample synthesized using Si3N4 as another nitrogen source contained a Ca2Al2SiO7 impurity. Thus, it was revealed that AlN was a preferable nitrogen source for the synthesis of Ca3Al8Si4O17N4 by the SSR method. The solid solutions around x = 4/3 activated with Eu2+ exhibited bluish-green luminescence with emission maxima at 480 nm by the excitation at 250 - 450 nm. Thus, the CaAl4-xSixO7-xNx: Eu2+ solid solutions especially for Ca3Al8Si4O17N4:Eu2+ (x = 4/3) were developed as novel展开更多
基金This work was supported by the National Key Basic Research Program of China （No.2013CB921800）, the National Natural Science Foundation of China （No.11374291, No.11311120047, No.11274299, No.11447197, and No.11204292）, the Fundamen- tal Research Funds for the Central Universities （No.WK20304200）, the Anhui Provincial Natural Science Foundation （No.1508085QA09）. The numerical calculations have been partially done on the super- computing system in the Supercomputing Center of University of Science and Technology of China.
文摘Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3＋ centers in Ca3Sc2Si3O12 by considering the effects of the charge com- pensations related to N3-, Sc3＋, Mn2＋, Mg2＋, and Na＋. Firstly, the local structures around Ce3＋ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce3＋ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3＋-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3＋ substituting Si4＋. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.
文摘Synthesis of oxynitride solid solutions CaAl4-xSixO7-xNx:Eu2+ (x = 0 - 4) was attempted by the solid state reaction (SSR) methods using Si3N4 and AlN as nitrogen sources. The Ca3Al8Si4O17N4 (x = 4/3) sample with the high phase purity was obtained when AlN was used as a nitrogen source whereas the sample synthesized using Si3N4 as another nitrogen source contained a Ca2Al2SiO7 impurity. Thus, it was revealed that AlN was a preferable nitrogen source for the synthesis of Ca3Al8Si4O17N4 by the SSR method. The solid solutions around x = 4/3 activated with Eu2+ exhibited bluish-green luminescence with emission maxima at 480 nm by the excitation at 250 - 450 nm. Thus, the CaAl4-xSixO7-xNx: Eu2+ solid solutions especially for Ca3Al8Si4O17N4:Eu2+ (x = 4/3) were developed as novel
