Subsolidus Phase Relations in the BaO-TiO₂-Fe₂O₃ System

Abstract
The subsolidus phase equilibrium relation in the BaO-TiO₂-Fe₂O₃ system at 1240°C in air has been investigated by conventional solid state reaction techniques and X-ray powder diffraction. Twelve quarternary compounds were recognized, BaTi_1-xFe_xO_3-z (N), Ba₃TiFe_l0O₂₀ (K), BaTi₂Fe₄O₁₁ (R), Ba₂Ti₄Fe₂O₁₃ (J), Ba_xTi_4-2xFe_2xO₈, (H), Ba₁₂Ti₁₆Fe₃₀O₈₉ (I), Ba_3.5Ti₅Fe₂₃O₄₈ (O), Ba_1.8Ti_4.4Fe_13.6O₃₁ (L), BaTi₂O₅ (0.2 mol% Fe₂O₃) (Q), Ba₂Ti_4.73Fe_0.27O_11.865 (P), Ba₅Ti₁₃Fe₂O₃₄ (A), and Ba₈Ti₁₆Fe₆O₄₉ (B). The phases J, I, O, L, Q, P, A and B are new compounds found in this study. Oxidation of Fe³⁺ to Fe⁴⁺ was observed in the BaO rich region (50 mol%). Ba₁₂Ti₁₆Fe₃₀O₈₉ (I) is a ferrimagnet with a T_c around 130°C.