Phase evolution of Ba_1-xEuxTi_1-x/4O₃during the sintering process in air with high temperature in situ X-ray diffraction

The phase evolution of Ba_1-xEuxTi_1-x/4O3 during the sintering process (heating and cooling) in the air with x ≥ 0.0054, 0.0384, 0.1920, and 0.2689 mol% Eu₂O₃was investigated by high temperature in situ X-ray diffraction in the range of temperature between 30 and 1200 °C. The samples were prepared mixing BaCO₃, TiO₂and Eu₂O₃powders using the solid-state method. The results obtained for the samples with x = 0.2689 mol% Eu₂O₃showed the cubic phase BaTiO₃doped with Eu³⁺at 900 °C. Below 500 °C the tetragonal ferroelectric phase BaTiO3 doped with Eu³⁺was detected. The secondary phase Ba₂TiO₄was identified in the samples when heated to 1100°C with x = 0.0054, 0.0384 and 0.2689 mol% Eu₂O₃and at 1200 °C for x = 0.1920 mol% Eu₂O₃. The secondary phases Eu₂Ti₂O₇and Eu₂TiO₅were identified during cooling in the temperature range of 1200 °C to room temperature for the sample with x = 0.1920 and 0.2689 mol% Eu₂O₃. The results of highresolution scanning electron microscope (HRSEM) showed a wide grain-size distribution, a partially homogeneous microstructure and higher amounts of inter-granular porosity as well as a uniform incorporation and distribution of Ti, Ba and Eu in each sample.