THERMODYNAMIC CALCULATIONS OF DEBYE-WALLER FREQUENCY INTEGRALS OF ALKALINE EARTH FLUORIDES

The maximum frequencies of the Debye distributions having the same n‐th moments as the vibrational frequency spectra in CaF2, SrF2, and BaF2, calculated from specific heat, thermal expansion, and elastic constant data, have been applied in the quasi‐harmonic approximation to calculate the Debye‐Waller frequency integrals of these solids. High‐and low‐temperature series expansions and Padé approximants have been employed to calculate these parameters as functions of temperature between 0 and 300 °K. Good agreement is observed between the values calculated for CaF2 and BaF2 at room temperature and those based upon neutron diffraction studies. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim