Phase diagram studies in the SrO–Cr 2O 3–La 2O 3 system in air and under low oxygen pressure

Abstract

Phase equilibria were determined in the complete composition range of the SrO–Cr 2O 3–La 2O 3 system in air at 1223 K and under low oxygen pressure (high vacuum, p(O 2)≈10 −9 bar). The (La,Sr)CrO 3 perovskite phase is the only quasi ternary oxide phase stable in air. The quasi ternary Ruddlesden–Popper phases (La,Sr) n+1Cr n O 3 n+1 ( n=1,2,3) were identified in addition to the perovskite phase in the samples annealed under low oxygen pressure. The solubility limit of strontium in the La 1− x Sr x CrO 3 phase was determined at 1223 K as x=0.10±0.02 in air and at 1873 K as x=0.31±0.02 under low oxygen pressure. The crystal lattice parameters of the Ruddlesden–Popper phase LaSrCrO 4 were obtained by the analysis of XRD patterns.