Thermodynamic Calculations of the Debye‐Waller Frequency Integrals of Alkaline Earth Fluorides

Abstract

The maximum frequencies of the Debye distributions having the same n-th moments as the vibrational frequency spectra in CaF,, SrF,, and BaF,, calculated from specific heat, thermal expansion, and elastic constant data, have been applied in the quasi-harmonic approximation t o calculate the Debye-Waller frequency integrals of these solids. Highand low-temperature series expansions and Pad6 approximants have been employed to calculate these parameters as functions of temperature between 0 and 300 OK. Good agreement is observed between the values calculated for CaF, and BaF, a t room temperature and those based upon neutron diffraction studies.