Defect Structure and Phase Relations of Highly Lanthanum‐Doped Barium Titanate

Incorporation of La 3+ into the BaTiO 3 lattice was studied on samples of various composition, using quantitative WDS microanalysis (EPMA) in combination with scanning electron microscopy (SEM) and X‐ray powder diffractometry (XRPD). Direct determination of solid‐solution formulas by microanalysis supports the structure model of a solid solution with La 3+ on Ba 2+ sites and a deficient Ti 4+ sublattice, independent of the starting composition. Solid solution extends on the tie line, which points from BaTiO 3 to La 4 Ti 3 O 12 , to the composition of approximately Ba 0.70 ‐ La 0.38 Ti 0.925 ( V ″″) 0.075 O 3 . On the basis of these results, the BaTiO 3 ‐rich part of the BaO‐La 2 O 3 ‐TiO 2 phase diagram was constructed.