Inverse barocaloric effects in ferroelectric BaTiO3 ceramics

We use calorimetry to identify pressure-driven isothermal entropy changes in ceramic samples of the prototypical ferroelectric BaTiO3. Near the structural phase transitions at ∼400 K (cubic-tetragonal) and ∼280 K (tetragonal-orthorhombic), the inverse barocaloric response differs in sign and magnitude from the corresponding conventional electrocaloric response. The differences in sign arise due to the decrease in unit-cell volume on heating through the transitions, whereas the differences in magnitude arise due to the large volumetric thermal expansion on either side of the transitions.