Pyroelectric performance of porous Ba0.85Sr0.15TiO3 ceramics

Porous Ba0.85Sr0.15TiO3 (BST) ferroelectric ceramics were synthesized by sintering compacts consisting of BST and Poly(methyl methacrylate) (PMMA) (2%, 4%, 6%, 8%, and 10% by wt.) as pore-forming agent. Systematic investigation of role of porosity on microstructural, dielectric, and pyroelectric performance is carried out. It is observed that as PMMA increased from 0% to 10%, the porosity increased from 7.5% to 29.5%. Dielectric constant decreases and dielectric loss increases with increasing PMMA content at fixed frequency. When porosity reached 29.5%, the relative dielectric constant of the BST composition decreased by more than 78% (from 3500 to 750) at 10 kHz and 300 K. Porosity leads to a significant reduction in dielectric constant and volume-specific heat capacity, which are of great interest for improving pyroelectric figure of merits (FOMs). Further, the pyroelectric figure of merits for current responsivity (F-i), voltage responsivity (F-v), detectivity (F-d), and energy harvesting (F-e and F-e*) are calculated for all investigated compositions. Compared with dense ceramic, porous BST (10% PMMA) showed an improvement of F-d by 19%, F-e by 61%, and F-e* by 98%. F-v increased by 210% at 300 K/10 kHz. All of these advancements are favorable for the development of pyroelectric devices.