Disorder, pseudo symmetry and photoluminescence properties of a new diphosphate K2Ba3(P2O7)2

Abstract

Abstract A new ternary metal diphosphate (V) K2Ba3(P2O7)2, has been prepared by high-temperature solution growth (HTSG) method for the first time. Structurally solution through single-crystal X-ray diffraction analysis method was complicated by pseudo centering symmetry combined with occupational disorder. The results show that it features a non-centrosymmetric space group Pmn21 with a = 5.5827 (6), b = 9.4196 (9), c = 13.9150 (12) Å, β = 94.561(4)°, Z = 2, R[F 2 > 2σ(F 2)] = 0.028. The structure of K2Ba3(P2O7)2 contains isolated [P2O7] groups in four directions array with their holes occupied by the K+ and the Ba2+ cations. Furthermore, photoluminescence study showed that K2Ba3(P2O7)2 display both a wide emission bond around 408 ~ 422 nm and a sharp bond at around 484 nm (excited by 354 nm).