Optimization of Calcium-Zinc-Manganese Phosphate

Ca₉Zn_1−xMn_xNa(PO₄)₇ with x = 0.05, 0.1, 0.2, 0.4, 0.5, 0.7, and 1.0 (for short CZ_1–xM_xN) was synthesized by a standard solid-state method from stoichiometric mixtures of CaCO₃, ZnO, NH₄H₂PO₄, MnCO₃, and Na₂CO₃ reagents purchased from Sigma-Aldrich [6 (link)]. Firstly, the reagents with a chemical purity of 99.9% were heat-treated to remove possible moisture impurities. Moreover, this was performed to reliably eliminate the possible admixtures and maximize purity of the raw materials. After that, the stoichiometric mixtures were heated to 1373 K and kept for 24 h in a reducing atmosphere of activated carbon to enable the reaction. Powder X-ray diffraction patterns of the synthesized powders were checked using the ICCD PDF-4 database to ensure the absence of all extraneous reflections of the initial or intermediate phases.