Temperature dependence of the root-mean-square displacements of atoms in the range 22° to 500°C for NaF, NaCl, KCl and KBr

Abstract

Abstract The temperature dependence of the <u 2>½'s was studied in the temperature range 22 to 500°C for the individual atomic species of NaCl, NaF, KCl and KBr. An initial set of values computed by polynomial extrapolation according to the model by Buyers and Smith (1968) was corrected for quasi-harmonic effects. The results are in excellent agreement with experimental data on NaCl. Specifically the experimental ratios of 〈u 2〉½ for Na18° + to Na227°c + and Cl18° − to Cl227°c − c are 1.30 versus the value 1.32 here reported.