The effect of substituting of rare earth elements (R = Ho, Yb) on energetic characteristics of doped barium cerates

Highlights: • The BaCe_0.7Ho_0.2In_0.1O_2.85, BaCe_0.7Yb_0.2In_0.1O_2.85 compounds have been synthesized by solid state reactions. • The standard formation enthalpies and lattice enthalpies were measured by reaction calorimetry. The standard formation enthalpies and lattice enthalpies were increasing from BaCe_0.7Ho_0.2In_0.1O_2.85 to BaCe_0.7Yb_0.2In_0.1O_2.85. . The barium cerates doped by holmium, ytterbium and indium (BaCe_0.7Ho_0.2In_0.1O_2.85, BaCe_0.7Yb_0.2In_0.1O_2.85) as perspective ionic conductor materials for fuel cells with increased thermodynamic stability have been synthesized by solid state reactions. The study of energy characteristics with emphasis on determination of basic thermodynamic characteristics such as standard formation enthalpies and lattice enthalpies was carried out using reaction calorimetry. On the basis of experimental data it was shown that standard formation enthalpies and lattice enthalpies are increasing in absolute value from BaCeO₃ doped by holmium and indium to BaCeO₃ doped by ytterbium and indium. The dependences of energetic characteristics on radii of rare-earth elements were constructed; and explanation of dependences based on the Kapustinski formula was presented. Based on our studies, we can conclude that barium cerate doped by indium and ytterbium is the most promising compound for practical application from thermodynamic point of view.