Photoluminescence properties of an orange-red LaSr_(2)AlO_(5):Sm^(3+)phosphor prepared by the Pechini-type sol-gel process

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.