Temperature dependence of conventional and effective pyroelectric coefficients for compositionally graded BaxSr1−xTiO3 films

Ferroelectric thin films (∼1.2 μm) of ${\mathrm{Ba}}_x{\mathrm{Sr}}_{\text{1−x}}{\mathrm{TiO}}_3$ with gradients in composition normal to the growth surface were formed on platinum substrates by metalorganic decomposition. Effective (pseudo) pyroelectric coefficients as large as $\text{0.06\hspace{0.17em}μ}{\mathrm{C/cm}}^2\hspace{0.17em}\mathrm{K}$ have been obtained from these active ferroelectric devices under the application of an ac field (charge pumping). In contrast, a value of only $\text{−0.003\hspace{0.17em}μ}{\mathrm{C/cm}}^2\hspace{0.17em}\mathrm{K}$ has been measured for the conventional pyroelectric coefficient.