Dependence of the pyroelectric response on internal stresses in ferroelectric thin films

The role of internal stresses on the pyroelectric properties of ferroelectric thin films is analyzed theoretically via a thermodynamic model. The pyroelectric coefficient as a function of the misfit strain is calculated for (001) Ba0.6Sr0.4TiO3 epitaxial thin films. It is shown that this property is highly dependent on the misfit strain. A very large pyroelectric response (0.65 μC/cm2 K) is theoretically predicted at a critical misfit strain (∼−0.05%) corresponding to the ferroelectric to paraelectric phase transformation. The analysis shows that internal tensile stresses are particularly not desirable with significant degradation close to an order of magnitude in the pyroelectric response.