Heat capacity and thermodynamic properties of lanthanum orthoniobate

Highlights: • Heat capacity of LaNbO₄ was measured by two calorimetric methods. • The second-order phase transition was detected by DSC. • Standard thermodynamic functions were calculated in the temperature range (2–1600) K. -- Abstract: Temperature dependences of the heat capacity and the enthalpy change of LaNbO₄ were measured using various calorimetric methods (adiabatic, differential scanning and drop calorimetry). It was confirmed that heat capacity has a step-like form in the region of the phase transition, and the second order phase transition "fergusonite-scheelite" proceeds without a thermal effect. Based on the smoothed values of heat capacity, thermodynamic functions (entropy, enthalpy change and Gibbs energy) were calculated over the temperature range from (2–1600) K.