The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln ...The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln and N-Ln,5d orbitals of Ln have large contribution in all valence orbitals of Ln and 4f orbitals have very small contribution.(2)The covalent chara- cter and ionic character are almost equal in the chemical bond which is comparatively weak between phen,C_2H_5OH and Ln are mainly ionic with some covalent character.展开更多
LaSr2A1Os：Sm3＋ phosphors were synthesized by the Pechini-type sol-gel process. The X-ray diffraction pattern revealed that a pure LaSr2AIO5 phase was obtained with a sintering temperature of 1200 ℃. Microstructure ...LaSr2A1Os：Sm3＋ phosphors were synthesized by the Pechini-type sol-gel process. The X-ray diffraction pattern revealed that a pure LaSr2AIO5 phase was obtained with a sintering temperature of 1200 ℃. Microstructure characterization showed that the particles were spherical in shape with a mean size of 2.93 μm. Being a candidate orange/red emitting phosphor for orange and white light emitting diodes, LaSr2A1Os：Sm3＋ could be effectively excited by both near-ultraviolet （NUV） and blue lights with typical f-f transitions of Sm3＋ ions. The most intense emission corresponding to 4G5/2---＊6H7/2 （604 nm） could be achieved at the same Sm3＋ concentration of 4 mol.%. The chromaticity coordinates of La0.96Sr2A1Os：0.04Sm3. phosphor under the excitation of 407 and 458 nm were （0.57, 0.43） and （0.59, 0.38）, respectively. Further study was carried out using Van Uitert＇s and Dexter＇s models. A consistent result was obtained that electric dipole-dipole interaction was dominant for the energy transfer among Sm3＋ ions. The critical distance for energy transfer among Sm3＋ ions in LaSr2A105 was calculated to be ca. 1.843 nm.展开更多
基金National Natural Science Foundation of China(61205180)Natural Science Foundation of Hebei Province,China(A2012201013)Distinguished Young Scholars of Hebei University(2012JQ01)
文摘The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln and N-Ln,5d orbitals of Ln have large contribution in all valence orbitals of Ln and 4f orbitals have very small contribution.(2)The covalent chara- cter and ionic character are almost equal in the chemical bond which is comparatively weak between phen,C_2H_5OH and Ln are mainly ionic with some covalent character.
基金supported by the Funding of Jiangsu Innovation Program for Graduate Education(CXZZ12_0147)funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘LaSr2A1Os：Sm3＋ phosphors were synthesized by the Pechini-type sol-gel process. The X-ray diffraction pattern revealed that a pure LaSr2AIO5 phase was obtained with a sintering temperature of 1200 ℃. Microstructure characterization showed that the particles were spherical in shape with a mean size of 2.93 μm. Being a candidate orange/red emitting phosphor for orange and white light emitting diodes, LaSr2A1Os：Sm3＋ could be effectively excited by both near-ultraviolet （NUV） and blue lights with typical f-f transitions of Sm3＋ ions. The most intense emission corresponding to 4G5/2---＊6H7/2 （604 nm） could be achieved at the same Sm3＋ concentration of 4 mol.%. The chromaticity coordinates of La0.96Sr2A1Os：0.04Sm3. phosphor under the excitation of 407 and 458 nm were （0.57, 0.43） and （0.59, 0.38）, respectively. Further study was carried out using Van Uitert＇s and Dexter＇s models. A consistent result was obtained that electric dipole-dipole interaction was dominant for the energy transfer among Sm3＋ ions. The critical distance for energy transfer among Sm3＋ ions in LaSr2A105 was calculated to be ca. 1.843 nm.
