Crystal structure and luminescence properties of a novel single-phase orange-red emitting phosphor CaLa (PO):Sm.

CaLa (PO):Sm phosphors (0.01 < < 0.25) were synthesized high temperature solid-state reaction. Their properties including crystal structure, decay performance, thermal stability and photoluminescence were examined in detail. Phase analysis indicated that the phosphors crystallized in a rhombohedral structure, and the emission spectra of the phosphors consisted of four peaks centered around 570, 607, 653, and 714 nm, attributed to Sm ions transitions G → H ( = 5/2, 7/2, 9/2, and 11/2, respectively). The optimal Sm doping content was 0.12 mol and the CaLa(PO):Sm phosphor also exhibited better thermal stability compared to other phosphors. In addition, the mechanism behind the energy transfer between Sm ions was determined to be dipole-dipole interactions as described by Dexter theory. The results indicated that as orange-red phosphors, CaLa (PO):Sm phosphors were promising candidates for being integrated into white light emitting diodes.