Microstructure of Ba1−xLaxTiO3−δ ceramics sintered by Spark Plasma Sintering

Nano-sized Ba1-xLaxTiO3-delta (x = 0.00-0.14) powders were prepared by coprecipitation and calcined at 850 C in air. The corresponding ceramics were obtained by spark plasma sintering at 1050 C. The ceramics were oxygen deficient and marked as Ba1-xLaxTiO3-delta. Both powders and ceramics were characterised by XRD and TEM. The effect of lanthanum concentration on the densification behaviour, structure and microstructure of the oxides was investigated. The average grain sizes were between 54(3) nm and 27(2) nm for powders, and 330(11) nm and 36(1) nm for the ceramics according to the La-doping level. The powders crystallised in a cubic (or pseudo-cubic) perovskite phase. The structure of ceramics consisted of a mixture of cubic (or pseudo-cubic) and tetragonal perovskite type phases. As the lanthanum content increased, the tetragonality of the samples decreased, as well as the grain size.