The spherical symmetry of the ions in potassium chloride crystal

The measured structure factors for KCl at 300°K, including corrections due to the thermal diffuse scattering and dispersion, are given. The absolute scale of the structure factors has been obtained by a direct intensity measurement of the primary X-ray beam with use of both Cu Kα and Mo Kα radiation. The Debye–Waller factors and the ionic radii derived from the measured structure factors are 2.08 ± 0.05 Ų, 2.06 ± 0.05 Ų, 1.45 ± 0.07 Å and 1.70 ± 0.07 Å for K⁺ and Cl⁻, respectively. The calculations of the radial coefficients of the cubic harmonic expansion for K⁺ and Cl⁻ indicate that these ions are almost exactly spherically symmetric.