Abstract
The dielectric properties of single-crystal and ceramic BaTi and of single-crystal SrTi were investigated as functions of hydrostatic pressure to 25 kbar and temperature to 150°C. The Curie point of BaTi decreased linearly with increasing pressure, but at a rate which varied from -4.6 to -5.9°C/kbar for different samples. Its spontaneous polarization decreased slowly (<2% per kbar) up to the transition pressure, where it dropped rapidly. This change in is primarily due to the displacement of the Curie point to lower temperatures. At constant temperature, the dielectric constant in the cubic phase of both compounds obeys the relationship . At 25°C, kbar and kbar for pure single-crystal BaTi, and kbar and kbar for single-crystal SrTi. Both and change with temperature. Similarly, the Curie-Weiss constant and temperature change with pressure. The temperature dependence of is separated into volume-dependent and volume-independent contributions, and it is shown that the change of the infrared polarizability with temperature at constant volume is the predominant factor in determining the change in .
- Received 27 May 1966
DOI:https://doi.org/10.1103/PhysRev.151.378
©1966 American Physical Society