Synthesis and study of cesium-containing phosphates with a β-tridymite structure

Complex phosphates CsMg 1 − x M x PO 4 (M = Mn, Co, Cu, Zn), containing cesium and metals in the oxidation state +2, have been synthesized, and their structure and thermal behavior have been studied. Continuous solid solutions (0 ≤ x ≤ 1) of the β-tridymite structure type are formed in the CsMg 1 − x Mn x PO 4 , CsMg 1 − x Co x PO 4 , and CsMg 1 − x Zn x PO 4 systems, whereas limited solid solutions (0 ≤ x ≤ 0.4) are formed in the CsMg 1 − x Cu x PO 4 system. Based on DTA data, phase transitions have been revealed in the cobalt-, copper-, and zinc-containing phosphates, and the orthorhombic or monoclinic crystal system has been identified. Unit cell parameters of the solid solutions have been calculated. Thermal expansion of the CsMPO 4 phosphates has been studied.