Thermodynamic stability and hydration enthalpy of strontium cerate doped with yttrium

The standard molar enthalpy of formation of SrY_0.05Ce_0.95O_2.975 has been derived by combining the enthalpy of solution in 1 M HCl + 0.1 KI with auxiliary literature data, Δ_fH° (SrY_0.05Ce_0.95O_2.975, s, 298.15 K) = −1720.4 ± 3.4 kJ/mol. The formation enthalpy of SrY_0.05Ce_0.95O_2.975 from the mixture of binary oxides is Δ_oxH° (298.15 K) = −45.9 ± 3.4 kJ/mol and the enthalpy of reaction of SrY_0.05Ce_0.95O_2.975 with water forming Sr(OH)₂, CeO₂, and Y₂O₃ is Δ_rH° (298.15 K) = −85.5 ± 3.4 kJ/mol. Our data and the entropies of different substances show that SrY_0.05Ce_0.95O_2.975 is thermodynamically stable with respect to a mixture of SrO, Y₂O₃, CeO₂ and that the reaction of SrY_0.05Ce_0.95O_2.975 with water is thermodynamically favourable.