Effect of Fe substitution at the B‐site on the pyroelectric properties of bismuth titanate ceramics

Abstract The effect of the B‐site substitution with the low‐valent Fe ion on the properties of lead‐free bismuth titanate (BNT) ferroelectric ceramics is explored. In this work, a series of ceramics with different Fe substitution concentrations are prepared. The Bi 0.5 Na 0.5 Ti 0.999 Fe 0.001 O 3 (BNTF‐0.1) ceramic has the highest depolarization temperature ( T d ≈ 213°C). The dielectric constant and dielectric loss fluctuate slightly with decreasing frequency. The pyroelectric coefficient p appreciably increases from 2.25 × 10 −4 C·m −2 ·K −1 for BNT to 2.88 × 10 −4 C·m −2 ·K −1 for BNTF‐0.1 at room temperature (RT). The figures of merit (FoMs) for BNTF‐0.1 component have also been improved at RT, where current figure of merit ( F i ) = 1.02 × 10 −10 m V −1 , voltage figure of merit ( F v ) = 3.51 × 10 −2 m 2 C −1 , and detectivity figure of merit ( F D ) = 1.66 × 10 −5 Pa −1/2 , which is attributed to its lower dielectric constant (∼330) and dielectric loss (∼0.0131). Between 20°C and 80°C, the values of the FoMs remain stable, with the F D of BNTF‐0.1 varying by only ±6.2%, indicating its superior temperature stability. These results confirm that low‐cost Fe substitution is an available strategy for optimizing the performance of BNT‐based ceramics. BNTF‐x ceramics would be excellent candidates for lead‐free pyroelectric infrared detection.