Phase equilibria in the BaTiO_3–La_2TiO_5–TiO_2 system

Subsolidus phase relations in the BaTiO_3–La_2TiO_5–TiO_2 part of the ternary BaO–La_2O_3–TiO_2 system at 1300 °C in air were determined. The phases were characterized by x-ray diffraction, scanning electron microscopy, and electron probe wavelength dispersive spectroscopic microanalysis. A combination of techniques was employed because of insensitivity in detecting secondary phases by x-ray diffraction. The location and extent of Ba_6− x La_8+2 x /3Ti_18O_54 ternary solid solution 0.2(1) ⩽ x ⩽ 2.3(1) and Ba_1− y La_ y Ti_1− y /4 (V_Ti)_ y /4O_3 binary solid solution 0 ⩽ y ⩽ 0.3 at 1300 °C was established. Tie lines between various barium polytitanates with a sequence of Ba_6− x La_8+2 x /3Ti_18O_54 solid solution regions were determined.

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