A synchrotron radiation study of potassium zinc fluoride perovskite

Vibration amplitudes and electron-deformation densities, Δρ, have been determined for KZnF3 from diffraction data measured using focused synchrotron radiation with λ=0.7000(2) A at the Photon Factory, KEK, Japan. The lack of systematic variation of intensity with path length indicates that secondary extinction is not significant, a result confirmed when the strong intensities measured using a weaker parallel beam with λ=0.5000(2) A showed no dependence on λ. The 0.7 A study is generally concordant with, but more precise (R=0.008, wR=0.006) than earlier analyses with Mo Kα radiation. The charge of +0.47(4) e determined for the Zn atom is larger than that calculated with extinction corrections which minimize differences between observed and calculated structure factors. Near the Zn nucleus Δρ is mildly anisotropic, with a topography similar to that found for closed-shell atoms in related perovskite structures. (orig.)