Abstract
The pyroelectric and dielectric properties of barium titanate crystals have been investigated in the temperature range from 300K to 150K. The pyroelectric coefficient has peaks at the tetragonal-orthorhombic transition and at the orthorhombic-rhombohedral transition. A thermal hysteresis of about 10K is recorded for the T-O transition and one of about 15K for the O-R transition. In the temperature range near the phase transitions, an unusual pyroelectric response was observed. Following a temperature variation, the pyroelectric charge changed its polarity with time. This behaviour can be attributed to the coexistence of two ferroelectric phases.