Crystal structure and luminescence properties of thermally stable Sm3+-doped Sr9In(PO4)7orange-red phosphor

A series of novel phosphate orange-red phosphor, Sr9In(PO4)(7):xSm(3+)(0.01 < 0.30), were successfully synthesized from high-temperature solid-state synthesis in this work. Their crystal structure has been analyzed by the Rietveld refinement, which shows Sr9In(PO4)(7)consists of a monoclinic cell (C2/c), which also confirms the successful doping, preferential site occupancy and local ligand environment of Sm3+. Luminescence properties of the samples have been systematically investigated including excitation and emission spectra, quantum efficiency, concentration quenching, fluorescence decay and temperature-dependent luminescence properties. Photoluminescence spectra exhibited typical peaks, corresponding to(4)G(5/2)->(6)H(J)transitions of Sm(3+)ions, whereJ= 5/2, 7/2, 9/2, and 11/2, respectively. Moreover, the concentration quenching result revealed that the optimal doping content of Sm(3+)was 0.15 mol, and based on the Dexter theory, the energy transfer between Sm(3+)ions was found in dipole-dipole interactions. The quantum yield of Sr9In(PO4)(7):0.15Sm(3+)phosphor was acceptable (58.5%). Most importantly, the emission intensity of Sr9In(PO4)(7):0.15Sm(3+)remains constant (>97%) below 150 degrees C and the configurational coordinate diagram analysis demonstrated excellent thermal stability of the Sr9In(PO4)(7):Sm(3+)phosphor, which is superior to that of the previously reported and commercially available phosphors. These results suggest that the Sr9In(PO4)(7):Sm(3+)phosphor is a promising orange-red phosphor materials for white light emitting diodes.