Cs6RE2(PO4)4 (RE = Y and Gd): two new members of the alkali rare-earth double phosphates†
Abstract
Two new alkali rare-earth double phosphates, Cs6Y2(PO4)4 (CYP) and Cs6Gd2(PO4)4 (CGP), have been successfully synthesized using the conventional solid-state reaction method. The two compounds crystallize in the same space group, P21 (no. 4), and feature a three-dimensional network composed of CsOn (n = 8, 10 and 11) distorted polyhedra and isolated YO6 and PO4 groups. IR spectroscopy, UV-vis-NIR diffuse reflectance spectroscopy, and electronic band structures of the two compounds are reported. In addition, the Ce3+-doped CYP and CGP phosphors were synthesized and their photoluminescence properties were investigated. The results indicate that the CYP:Ce3+ and CGP:Ce3+ phosphors can be efficiently excited by ultraviolet (UV) light to realize a blue luminescence corresponding to the electric-dipole allowed 4f–5d transition of the Ce3+ ions.