High pressure in situ differential thermal analysis of Na0.5Bi0.5TiO3 phase transitions up to 5 GPa

High pressure in situ differential thermal analysis (DTA) was applied to study phase transitions of Na0.5Bi0.5TiO3 (NBT) up to 5 GPa. DTA analysis at room temperature with pressure as the variable indicated NBT samples have two pressure induced phase transformations at about 0.7 GPa and 2.5 GPa respectively. Below 0.7 GPa, two temperature induced phase transitions could be observed at around 220 °C and 520 °C as it was reported at ambient pressure. But under a pressure higher than 0.7 GPa, these two temperature induced phase transitions would not happen. In situ electrical resistance measurements showed that the resistance of NBT changes smoothly, and the tendency is similar to that of electrical insulators like pyrophyllite. We suggest that the pressure induced phase transitions at 0.7 GPa and 2.5 GPa are both insulator to insulator phase transitions.

► Using DTA with pressure as variable to detect phase transitions.
► Pressure induced phase transitions of NBT happened at 0.7 Gpa and 2.5 GPa.
► Insulator to insulator phase transitions occurred at both 0.7 GPa and 2.5 GPa.
► Temperature induced phase transitions at 220 °C and 520 °C happened only below 0.7 GPa.