Synthesis, thermal expansion and optical properties of (1−x)NaAl(MoO4)2-xNaEr(MoO4)2 ceramics

(1−x)NaAl(MoO4)2-xNaEr(MoO4)2 ceramics with x = 0, 0.04, 0.08, 0.12, 0.16, 0.20 and 1.0 are synthesized by coprecipitation method, and their thermal expansion and room temperature optical properties are studied. It is found that the ceramics with two phases of monoclinic and tetragonal present large thermal expansion, and exhibit relatively strong near ultraviolet and green and weak red photoluminescence, which are also observed when excited with a 980 nm laser. With increasing photoluminescence of Er3+ ions in the ceramics, the intrinsic photoluminescence of the hosts is observed to decrease intensively. It could refer that excitation into the hosts is followed by an efficient energy transfer towards Er3+ ions. The relatively strong up-conversion green lights of the ceramics indicate the potential use as one of up-conversion materials.