Low-temperature thermodynamic properties of holmium selenide (2:3)

Holmium selenide Ho2Se3(cr) was synthesized and characterized by powder X-ray diffraction and energy dispersive analysis. The heat capacity of Ho2Se3(cr) has been measured by adiabatic method in the temperature range of (4.75-302.60) K. The pronounced λ-anomalies were found in Cp,m(T) dependence with the maxima at temperatures TC1 = 6.03 K and TC2 = 228.40 K. A conclusion was drawn that the phase transition associated with antiferromagnetic ordering is observed at TC1. The values of thermodynamic function (entropy, enthalpy and Gibbs reduced energy) were calculated from the experimental Cp(T) dependence. Absolute entropy value was used for calculation of Ho2Se3(cr) formation entropy at T = 298.15 K.