Crystal structure of KCaF3 determined by the Rietveld profile method

Abstract

Using the Rietveld profile method, the atomic coordinates and anisotropic temperature factors of KCaF3 were refined. At room temperature, KCaF3 crystallizes in monoclinic B21/m symmetry, with the lattice parameters: a=8.754(2) Å, b=8.765(4) Å, c=8.760(5) Å, β=90.48(3)°, V=672.1(3) Å3, Z=8. The refinement procedure was stopped when RB=0.05 and the Durbin–Watson statistic factor=0.85 had been reached. The structure determined is related to the tilting of CaF6 octahedra of the a−b+c− type, which are responsible for the monoclinic distortion in perovskite crystals.