| Popis: |
The phases deriving from Ba2CuO3+δ by partial substitution of lanthanum for barium atoms up to the limit composition Ba1.33La0.67CuO3+δwere investigated. The reaction environment was CO2 free air, in order to avoid any pollution of the samples by CO−−3 ions. At 950°C the system is characterized by the presence of two solid solution fields Ba2−xLaxCuO3+δ: the first shows tetragonal structure K2NiF4-type with disordered anionic vacancies and stretches from x=0 to x=0.05, the second has an orthorhombic structure deriving from that of Sr2CuO3 and extends from x=0.25 to x=0.67. Under 450°C the tetragonal phase disappears and we observe a unique solid solution fields, with orthorhombic symmetry |
