Synthesis, characterization and crystal structure of a new mixed alkali and alkaline-earth metal borate Rb9Ba24(BO3)19

Abstract

A new mixed alkali and alkaline-earth metal borate, Rb₉Ba₂₄(BO₃)₁₉, has been synthesized by a high-temperature solution method. Single crystal X-ray crystallographic investigation reveals that it crystallizes in the trigonal space group Pm1 (No. 164) with unit cell parameters of a = b = 16.977(3) Å, c = 7.282(2) Å, and Z = 1. Rb₉Ba₂₄(BO₃)₁₉ possesses an intricate three-dimensional (3D) Ba–O framework with three types of infinite channels viewing along the c axis where the Rb⁺ cations and isolated BO₃ units are located. The synthesis, single crystal growth, thermal behavior, IR spectrum and UV-vis-NIR diffuse reflectance spectrum of the title compound have been comprehensively studied.