Phase relations and electrical properties in the pseudo-ternary La2O3–TiO2–Mn2O3 system in air

Scanning electron microscopy (SEM), electron-probe microanalysis, energy- and wavelength-dispersive X-ray analysis and X-ray powder diffraction were used to investigate the subsolidus phase relations in the pseudo-ternary La2O3–TiO2–Mn2O3 system in air (oxygen partial pressure pO2=0.21   atmpO2=0.21   atm) at 1275 °C. The addition of Mn2O3 to the starting La2O3:3TiO2 mixture led to the formation of a La-deficient perovskite La2/3TiO3 compound. The oxides form two new compounds with the proposed compositions: (i) La1.7Ti13.0Mn6.3O38−x, with a davidite-like crystal structure, and (ii) La49Ti18Mn13O129. There were also several solid solutions existing over a wide range of concentrations.