Heat capacity by differential scanning calorimetry and thermodynamic functions of BaCe.sub.0.8Gd.sub.0.1Y.sub.0.1O.sub.2.9 in the temperature range of 166-790 K

In the present study, the heat capacities of barium cerate doped by gadolinium and yttrium oxides were measured for the first time in the temperature range of 166-790 K. The differential scanning calorimeter was used for investigation. There was reproducible anomaly with maximum at 601 K and minimum at 679 K. The experimental results were used to calculate the thermodynamic functions: smoothed heat capacities, enthalpy increment (Hmo (T) - Hmo (298.15)), and entropy (Smo (T)). The heat capacity in the temperature range of 166-602 K was described by a polynomial of the form: Cp,mo (T) = 83.140 + 0.14943 T - 1.1537 x 10.sup.-4T.sup.2 - 3.6358 x 10.sup.5/T.sup.2 (J mol.sup.-1 K.sup.-1). Heat capacity of BaCe.sub.0.8Y.sub.0.1Gd.sub.0.1O.sub.2.9 in the temperature range of 602-680 K was described by a polynomial: Cp,mo (T) = - 118.18 + 0.71961 T - 5.5387 x 10.sup.-4T.sup.2 + 5.6948 x 10.sup.+6/T.sup.2 (J mol.sup.-1 K.sup.-1). The heat capacity in the temperature range of 680-790 K was well described by the equation: Cp,mo (T) = 1987.1 - 6.9263 T + 8.3407 x 10.sup.-3T.sup.2 - 3.1992 x 10.sup.-6T.sup.3 (J mol.sup.-1 K.sup.-1).