Preparation and stability of a new compound SrCe_0.9Lu_0.1O_2.95

Highlights: • The phase SrCe_0.9Lu_0.1O_2.95 was synthesized. • The formation enthalpy of SrCe_0.9Lu_0.1O_2.95 was measured by solution calorimetry. • The phase is thermodynamically stable with respect to decomposition into binary oxides. • The adding of Lu leads to increasing the stability of SrCeO₃. - Abstract: The preparation of SrCeO₃ doped by lutetium oxide (SrCe_0.9Lu_0.1O_2.95) has been carried out by the solid-state reaction of SrCO₃, CeO₂ and Lu₂O₃. The X-ray measurements have shown that SrCe_0.9Lu_0.1O_2.95 has an orthorhombic structure (space group Pnma). For the first time the standard molar enthalpy of SrCe_0.9Lu_0.1O_2.95 formation has been determined by solution calorimetry in combination with standard molar dissolution enthalpies of SrCe_0.9Lu_0.1O_2.95 and SrCl₂ + 0.9CeCl₃ + 0.1LuCl₃ mixture in 1 M HCl with 0.1 M KI at 298.15 K and other thermochemical data. It has been found out that the mixed oxide mentioned above is thermodynamically more stable than the component oxides at room temperature. It has been also shown that SrCe_0.9Lu_0.1O_2.95 is thermodynamically more favored than 0.9SrCeO₃ + 0.1SrO + 0.05Lu₂O₃ mixture. We have established that Lu adding increases SrCeO₃ thermodynamic stability