Mechanochemical Syntheses of Perovskite KMIIF3 with Cubic Structure (MII = Mg, Ca, Mn, Fe, Co, Ni, and Zn)

Abstract

An equi-molar mixture of potassium fluoride (KF) and one of alkaline-earth or transition metal fluoride M^IIF₂ (M^II = Mg, Ca, Mn, Fe, Co, Ni, and Zn) was ground in air by using a planetary ball mill to investigate mechanochemical (MC) synthesis of fluoroperovskites KM^IIF₃. Rietveld refinement for the ground mixtures was conducted on the basis of XRD data to inquire into structural properties of the KM^IIF₃ synthesized mechanochemically. The synthesis reactions proceed with grinding time, and ultimately a single phase of cubic structural KM^IIF₃ (Pm3m, Z=1) was obtained after grinding for 21.6 ks. The values of unit cell parameter, a, of KM^IIF₃ synthesized by MC reaction, are slightly larger than those by solid-state reaction at high temperature, and this may be attributed to structural distortions caused by intensive grinding.