Comparative microwave- and conventional oven-assisted hydrothermal syntheses of BaTiO3 nanoparticles for improved electroceramics

Barium titanate (BT) nanoparticles were prepared using both microwave- and conventional oven-assisted hydrothermal syntheses with varying reaction times (1 h, 3 h, and 6 h). In the case of the conventional oven-assisted hydrothermal syntheses, 16 h, 24 h, 48 h and 72 h reaction times were also studied. Structural and morphological evolution of BT particles were investigated. Microwave-assisted hydrothermal synthesis allowed for the rapid formation of nearly pure barium titanate (BT) phase in just one hour at 200 °C. On the other hand, using a conventional oven as the heat source required at least 6 hours of synthesis to achieve a similar material. When the different BT powders were pelletized and sintered at 1300 °C, ceramics with over 95 % density were obtained. The room-temperature (RT) dielectric permittivity exceeded 1750 for BT particles prepared over 6 hours using both heating methods. However, a significant distinction emerged when comparing the piezoelectric coefficient (d33) values. The BT pellet obtained through the sintering of BT synthesized in the conventional oven for 6 hours exhibited a notably higher d33 value, approximately 171 pC/N, as opposed to the 146 pC/N value observed in BT ceramics resulting from the microwave synthesised powders. Among the ceramic BT variations, the one derived from the best-crystallized tetragonal BT particles (CON_72h) displayed the lowest d33 value at 79 pC/N. These findings underscore the immense potential of microwave- and conventional oven-assisted hydrothermal syntheses in the sustainable production of BT nanomaterials, which can then be sintered to enable the preparation of ceramics with enhanced ferroelectric and piezoelectric properties.