Enhancement of sintering rates in BaTiO₃ by controlling of DC electric current

DC electric fields ranged from 25 to 350 V/cm enhanced the sintering rates of BaTiO3. At the field of 25 V/cm, the sintering densification occurred by field-assisted sintering (FAST), and flash-sintering preceded by FAST was observed at the field strength of more than 75 V/cm. Most of the densification, however, was produced by the FAST process. At high field strength of more than 250 V/cm, the sintering densification was not finished owing to discharging during the flash-sintering. By means of FAST process at 100 V/cm and the current limit of 100 mA, in contrast, relative density of 97% and a fine grain size about 500 nm were achieved at 1020°C in the present material. The FAST process, where the electric current was set to the transition current between FAST and flash-sintering, is highly effective to fabricate uniform and fine grained BaTiO3 polycrystal.