Mechanochemical Syntheses of Perovskite KM<SUP>II</SUP>F<SUB>3</SUB> with Cubic Structure (M<SUP>II</SUP> = 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 MIIF2 (MII = 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 KMIIF3. Rietveld refinement for the ground mixtures was conducted on the basis of XRD data to inquire into structural properties of the KMIIF3 synthesized mechanochemically. The synthesis reactions proceed with grinding time, and ultimately a single phase of cubic structural KMIIF3 (Pm3m, Z=1) was obtained after grinding for 21.6 ks. The values of unit cell parameter, a, of KMIIF3 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.