Four-Component Perovskites in A-R-Fe-O Systems at 1200° (A - Alkaline-Earth, R - Rare-Earth Metal)

O. Zaremba, V. Hrytsan, R. Gladyshevskii Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St., 6, 79005 Lviv, Ukraine

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The formation of four-component perovskites in the A-R-Fe-O systems, where A is an alkaline-earth and R a rare-earth metal, was studied on the basis of the analysis of 36 polycrystalline samples synthesized by a multi-stage solid-state reaction method and annealed at 1200°. X-ray diffraction was chosen as the main method of investigation. The existence of A0.5R0.5FeO3 ternary compounds with CaTiO3-type perovskite structures (Pearson symbol cP5, space group Pm-3m) was shown in the {Ca,Sr}-R-Fe-O systems, i.e., Ca0.5Pr0.5FeO3 (a=3.8501(3) Å), Ca0.5Nd0.5FeO3 (a=3.8486(4) Å), Sr0.5Pr0.5FeO3 (a=3.8783(4) Å), Sr0.5Nd0.5FeO3 (a=3.8752(4) Å), Sr0.5Sm0.5FeO3 (a=3.8651(4) Å), and Sr0.5Eu0.5FeO3 (a=3.8653(2) {Å}). The remaining Ca0.5R0.5FeO3 samples contained as main phase R1-xCaxFeO3 solid solutions with orthorhombic structure (x up to 0.25, GdFeO3 type, oP20, Pnma), whereas the Sr0.5R0.5FeO3 samples contained SrxR1-xFeO3 solid solutions with cubic structure (x up to 0.4, CaTiO3 type). Annealing of Ba-containing samples at 1200° led to the formation of Ba1-xRxFeO3 (x ≃ 0.15) solid solutions based on the BaFeO3 phase (CaTiO3 type) for light rare-earth metals.

DOI:10.12693/APhysPolA.141.304 topics: alkaline-earth metal, rare-earth metal, iron, perovskite