Secondary thermal treatment effect on PTCR BaTiO3

The effect of secondary thermal treatments (450-650 C/10-30 min) on previously processed PTCR BaTiO3 samples was found to decrease the room temperature resistivity by 0.5 to 3 orders and enhance the PTCR jump accordingly. It is proposed that a strong internal stress exists near grain boundaries in modified barium titanate, which originates from the interaction between the elastic dipoles and spontaneous polarisation. Secondary thermal treatments result in a relief in the internal stress through the reorientation of oxygen vacancies, leading to more directional domain alignment, thereby more effective compensation to the electrical potential barrier. 16 refs.