[Synthesis and characterization of broadband IR-to-visible upconversion material caS : Ce, Sm by low-temperature...

Broadband IR-to-visible upconversion material CaS : Ce, Sm was synthesized for the first time by the low-temperature combustion synthesis (LCS) method. The effect of the rare earth dopant concentration on the upconversion properties was studied. XRD analysis shows that the sample features the cubic CaS crystal structure. The excitation spectrum of the sample is in the range of 200-500 nm, i. e. ultraviolet light or the visible light can excite the sample effectively to complete the "charged" process, and the excitation effect of the visible light is dominant. The IR sensitivity spectrum of the sample is in the range of 800-1 400 nm, indicating that CaS : Ce, Sm possesses the broadband IR-to-visible upconversion effect. The IR-to-visible upconversion spectrum of the sample is a broadband spectrum in the range of 450-650 nm, with two adjacent emission peaks at 513.4 and 572 nm, resulting from the transitions of Ce3+2T2g(5d)-->2F5/2 (4f) and the transitions of Ce3+2T2g(5d)-->2F7/2 (4f), respectively.