Low-temperature heat capacity of sodium erbium molybdophosphate Na2Er(MoO4)(PO4)

Adiabatic calorimetry is used to measure the low-temperature heat capacity of Na2Er(MoO4)(PO4)from 6.41 to 347.87 K. Experimental data are used to calculate the thermodynamic functions of Na2Er(MoO4)(PO4), which at 298.15 K are as follows: C p (298.15 K) = 243,3 - 0.4 J/(K mol), S (298.15 K) = 312.8 - 0.8 J/(K mol), H (298.15 K) - H (0 K) = 45280 - 90 J/mol, and Q(298.15 K) = 136.1 - 0.3 J/(K mol). A diffuse heat-capacity anomaly associated with splitting of the Stark levels (Schottky anomaly) is discovered in the low-temperature region.