Abstract
Solid-phase samples with the general formula Ba(La,Gd)2WO7 are synthesized in ternary oxide systems based on barium, lanthanum, gadolinium, and tungsten. Full-profile calculations of X-ray diffractograms are used to refine unit cell parameters and estimate the content of additional phases. Adiabatic calorimetry is used to investigate the temperature dependence of samples’ heat capacity in the helium range (4.25–325 K) and record anomalies caused by the doping element. The experimental heat capacities are corrected for the content of impurity compounds. Experimental data are used to reveal the lattice component of the heat capacity and calculate thermodynamic functions of the compounds in the range of 5–320 K, in order to determine changes in entropy and enthalpy in the domain of anomalies. The standard values of the Ba(La $$_{{1-x}}$$ Gdx)2WO7 thermodynamic functions are found to be x = 0.01, 0.03, and 0.05: $$C_{{p,298.15}}^{^\circ }$$ = 190.9 ± 1.5, 198.6 ± 1.5, and 207.0 ± 1.5 J/(mol K); $$S_{{298.15}}^{^\circ }$$ = 221.3 ± 12.9, 229.6 ± 13.3, and 229.1 ± 13.4 J/(mol K); and $$H_{{298.15}}^{^\circ }$$ – $$H_{0}^{^\circ }$$ = 34 161 ± 1379, 35 389 ± 1430, and 35 511 ± 1429 J/mol, respectively.