Crystal structure and thermal expansion of RbNaCaTh(Si8O20)

RbNaCaTh(Si₈O₂₀), which crystallizes in the turkestanite structural type, was synthesized by a solid-phase reaction for the first time. The crystal structure of this compound was refined by the Rietveld method (space group P4/mcc). The temperature dependence of the unit cell parameters was studied using high-temperature X-ray diffraction analysis, and the thermal expansion coefficients of this compound were determined.