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 M II F 2 (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 II F 3 . Rietveld refinement for the ground mixtures was conducted on the basis of XRD data to inquire into structural properties of the KM II F 3 synthesized mechanochemically. The synthesis reactions proceed with grinding time, and ultimately a single phase of cubic structural KM II F 3 (Pm3m, Z ¼ 1) was obtained after grinding for 21.6 ks. The values of unit cell parameter, a, of KM II F 3 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.

An Ab Initio Perspective on the Key Vacancy Defects of KMgF3

“…221), where the center of a F 6 octahedron is occupied by divalent Mg 2+ ion, and the corners of a cube are occupied by the 12-fold coordinated K + ion (Figure 1a). The optimized lattice parameter for the KMgF 3 unit cell within the PBE level is found to be 4.030 Å, which is in line with the experimentally reported values of cell parameters (3.993−4.006 Å) 57,58 and previous computational results (4.040, 41 4.033, 43 and 4.064 Å). 59 This justifies the choice of computational methodology.…”

Calculated high-pressure structural properties, lattice dynamics and quasi particle band structures of perovskite fluorides KZnF3, CsCaF3and BaLiF3

“…5 Several experimental studies focused on synthesis, lattice dynamics, high-pressure structural stability, elastic constants, optical absorbtion and photoluminescence. [6][7][8][9][10][11][12] In addition, several theoretical studies of KZnF 3 investigated its electronic structure and optical properties, lattice dynamics and thermodynamic properties, crystal fields and influence of 3d transition metals dopants. [13][14][15][16] Similar to KZnF 3 , the CsCaF 3 perovskite also was investigated in several experimental and theoretical studies addressing the electronic structure and optical properties, low energy phonon dispersion curves, green luminescence upon Eu 2+ doping, thermodynamics at low temperatures, and the equation of state.…”

High-pressure structural, electronic and optical properties of KMgF3: A first-principles study

“…Experimental studies have been performed to determine the ground state properties [4][5][6][7][8] and elastic constants at ambient pressure [9,10] and their dependence with pressure and temperature [11]. The high-pressure structural behavior of KMgF 3 was recently investigated by the high-pressure powder Xray diffraction [12].…”