Theoretical and Experimental Studies of Thermodynamic Properties, Anharmonic Effects and Structural Determination of HCP Crystals

Abstract

Thermodynamic properties, anharmonic effects and structural determination of hcp crystals have been studied based on their theoretical and experimental Debye-Waller factor presented in terms of cumulant expansion up to the third order in X-ray absorption fine structure (XAFS). The results have been achieved based on the present advanced method using that the calculations and measurements are necessary only for the second cumulants from which all the considered XAFS quantities have been provided. This advantage has resulted based on the description of XAFS quantities in terms of second cumulants. The many-body effects included in the present one-dimensional model have been taken into account based on the first shell near neighbor contributions to the vibration between absorber and backscaterer atoms. Morse potential is assumed to describe the single-pair atomic interaction included in the anharmonic interatomic effective potential. Numerical and experimental results for Zn in hcp phase obtained by the present advanced method are found to be in good agreement with one another and with those measured at HASYLAB (DESY, Germany).