Thermodynamic Data of Gadolinium–Strontium Phosphate

Abstract

Gadolinium–strontium phosphate with the eulytite structure was synthesized. Its structure refinement was performed applying the Rietveld method. The isobaric heat capacities of phosphate Sr₃Gd(PO₄)₃ have been measured from T = 6 to 800 K by adiabatic vacuum and differential scanning calorimetry. The standard thermodynamic functions C_p,m⁰, [H_m^o(T) – H_m^o(6)], [S_m^o(T) – S_m^o(6)], and Φ_m^o in the range of T → 6–800 K were calculated from the experimental data. Thermal expansion of phosphate using X-ray diffraction was studied in the temperature range 298–473 K. The linear thermal expansion coefficient was α = 12.1 × 10^–6 K^–1.