Synthesis of barium ferrates in oxygen

Abstract

Phase relations in th e system Bao-Fe203-"FeO," at 1 atm (1 atm= 1.013 X 1()' N/m') oxygen and be twee n 800 to 1050 °C are s hown in th e vicinity (high Ba portion) of the 1:1 cation-cation ratio co mposition. A hexagonal BaTi03-like phase, BaFe03 _X (a = 5.676A ,c= 13_ 934A), exists below %O °C. A perovs kite-lik e phase BaFeO:J_x' occurs be twee n %0 and 1050 0C. Single-phase tetragonal perovskite can be obtained at room temperature by quenching composition § with Ba-Fe ratios of 67:66 (a=3.985 A, c= 4.00S A, 1000 0c) and 27:26 (a=3.988 A, c=4.003 A, 1000 0c) from above 960°C. At the 17:16 ratio , single phase cubic perovskite(a= 3.994-A, 1000 °C), can be synthesized. Influence of te mperature , additions of barium, and use of Pt-contain ers on phase relations are discussed.