Heat capacity measurement of (Cr − xFe x) 3Te 4 ( x = 0−0.1) at high temperatures

Abstract

Heat capacities of (Cr − x Fe x ) 3Te 4 ( x = 0, 0.02, 0.04 and 0.1) were measured from 325 to 920 K by using an adiabatic scanning calorimeter. The sample of x = 0.1 showed two heat capacity anomalies. For x = 0, 0.02 and 0.04, heat capacity anomalies were observed at 904, 900 and 890 K, respectively, presumably due to the order-disorder of chromium atoms and vacancies in (Cr − x Fe x ) 3Te 4. The transition enthalpy and entropy due to the order-disorder of chromium atoms and vacancies were determined from excess heat capacities. It was found that transition temperatures, enthalpies and entropies decreased with increasing iron contents, indicating that some of the nearest neighbor chromium vacancies neighboring iron sites may not contribute to the order-disorder transition. From the heat capacity, it was found that the solubility limit of iron to Cr 3Te 4 was between x = 0.04 and 0.1.