Potentiality of Bi and Mn co-doped lead-free NaNbO3 ceramics as a pyroelectric material for uncooled infrared thermal detectors

The pyroelectric materials have immense applications in the uncooled infrared thermal detectors. However, owing to increasing environmental concerns due to Pb element, it is required to explore novel, high-performance, environmental-friendly pyroelectric materials. This is the first study to report about the pyroelectric properties of lead-free NaNbO3 ceramics, which displayed a high pyroelectric coefficient of 1.85 × 10−8 C cm-2 K−1 and figures of merit as Fi = 0.67 × 10−10 m V−1, Fv = 3.33 × 10−2 m2 C−1, and Fd = 5.32 × 10-5 Pa−1/2 at room temperature. Also, highly temperature-stable pyroelectric characteristics were also observed in NaNbO3 ceramics due to the high depolarization temperature of 280 ℃. The high pyroelectric properties and temperature stability were a result of the electric field induced irreversible phase transition from antiferroelectric to ferroelectric. Hence, we can conclude that lead-free NaNbO3 ceramics are a novel and promising candidate for pyroelectric detectors in a wide temperature range, especially for large area detectors and pyroelectric point detector.