The Double Molybdate Rb2Ba(MoO4)2: Synthesis, Crystal Structure, Optical, Thermal, Vibrational Properties, and Electronic Structure

The double molybdate Rb2Ba( MoO4) 2 was synthesized by high temperature solid- state reaction. According to the single- crystal X- ray diffraction structure determination, it is isostructural to the mineral Palmierite K2Pb( SO4) 2 in the trigonal space group R3 m. Its structure can be described as layers of MoO4 tetrahedra corner- sharing with distorted BaO6 octahedra, while the layers are separated by bi- layers of rubidium cations in 10- coordinate environment. UV/ Vis- NIR spec- troscopy measurement indicates that Rb2Ba( MoO4) 2 has an indirect bandgap of 4.40 eV, comparable to the calculated value 4.21 eV. The DSC test demonstrates the melting point and incongruent melting characteristic of the title compound. About seven narrow Raman lines were observed in the Raman spectrum recorded for Rb2Ba( MoO4) 2 powder sample.