Temperature measurement by extended X-ray absorption fine structure: A new theoretical development

Abstract

In the recent paper Ye et al. (2020) presented a theoretical development on the measurement of temperature by extended X-ray absorption fine structure (EXAFS) based on the anharmonic correlated Debye model. The authors showed that their new developed approach could derive accurate actual temperatures. In this work, we propose another theoretical development on the basic of the anharmonic correlated Einstein model which could give the same accurate order as in Ye et al.’ work. By making numerical calculations for gold, iron, vanadium and titanium metals up to temperature more than 1300 K we show that the thermal disorder gives significant contribution to the EXAFS Debye–Waller factors at high temperature, especially at temperature that is higher than the Debye temperature. Gold metal has the lowest threshold temperature (about 50 K) at which the second EXAFS cumulant curve becomes linearly. And Fe–Fe, V–V, and Ti–Ti bonds are stiffer than Au-Au bonds. This causes the weaker dynamic disorder in Fe–Fe, V–V, and Ti–Ti systems in comparison to Au metal. Furthermore, our calculated temperatures derived from anharmonic correlated Einstein model are reasonably accurate to the actual temperatures with small deviation. It reflects the fact that the anharmonic correlated Einstein model is reliable and effective to study thermodynamic quantities in EXAFS theory.