X‐ray Diffraction and Microstructural Investigation of the Al2O3‐La2O3‐TiO2 System

The ternary phase diagram of Al[sub 2]O[sub 3]-La[sub 2]O[sub 3]-TiO[sub 2] at 1,400 C was determined with 12 compatibility triangles. Al[sub 2]O[sub 3] stabilizes the A-site-deficient La[sub 2/3]TiO[sub 3] perovskite structure. According to XRD and microstructural investigations, the solid solution extends along the La[sub 2/3]TiO[sub 3]-LaAlO[sub 3] tie line from at least 4 mol% LaAlO[sub 3] to pure LaAlO[sub 3]. With increasing LaAlO[sub 3] content, the stabilized La[sub 2/3]TiO[sub 3] structure changes from orthorhombic via tetragonal to cubic.