Dependence on temperature and pressure of second cumulant and correlation effects during EXAFS in intermetallic alloys.

The present article is aimed to investigate the second cumulants, and the thermodynamic quantities are dependent on temperature and pressure in the X-ray absorption fine structure spectrum. The expressions have been build by using the model of the non-harmonic correlation of Einstein and Debye. A simple calculation was used to instead complex problems caused by the interaction of many particles in the system. The significant results of this work are the Morse potential parameters have been theoretically calculated method, determined the temperature dependence of the second cumulant, mean square displacement and correlation function for copper, tungsten, and copper-tungsten alloy of ratio 93-07 percent (WCu) under pressure up to 14GPa. Calculated the second cumulant dependence on the pressure in a range from 0GPa to 14GPa and clearly analysed the difference between the second cumulant at different pressure for atoms of tungsten, copper and tungsten-copper alloy. Numerical results according to the present theory agree well with experimental data and previous views.