Superior piezoelectric performance in ytterbium-substituted high-TC Bi5Ti3FeO15

High-temperature piezoelectric materials are essential for advanced sensor applications. However, it is challenging to achieve both high piezoelectric performance and a broad service temperature range. Aurivillius-type bismuth layer-structured ferroelectric (BLSF) bismuth titanate-ferrite (Bi5Ti3FeO15) has recently received significant attention. However, the piezoelectric properties of Bi5Ti3FeO15-based compounds have not been extensively explored due to their poor piezoelectric performance and low direct-current (dc) electrical resistivity at elevated temperatures. To address these limitations, we optimized the composition by partially substituting A-site bismuth ions with rare-earth ytterbium ions. This substitution aimed to enhance the piezoelectric performance, dc electrical resistivity, and thermal stability of the piezoelectric properties. We conducted a detailed examination of the crystal structure, microstructural morphology, and piezoelectric properties of ytterbium-substituted Bi5Ti3FeO15. The optimal composition, 4 mol% ytterbium-substituted Bi5Ti3FeO15 (BTF-4Yb), exhibits a significantly improved piezoelectric constant (d33) of 21.4 pC/N, which is three times higher than that of Bi5Ti3FeO15 (7.1 pC/N). Additionally, it shows a high dc electrical resistivity of 1.6 MΩ cm at 400 °C and a high Curie temperature (TC) of 771 °C. Importantly, BTF-4Yb maintains good thermal stability of electromechanical coupling characteristics up to 300 °C. These results indicate that ytterbium-substituted Bi5Ti3FeO15 is a promising candidate for high-temperature piezoelectric ceramics, offering significant potential for applications in high-temperature piezoelectric sensors. •A high piezoelectric constant (d33) of 21.4 pC/N was achieved in Bi5Ti3FeO15 with 4 mol% ytterbium substitution.•Bi5Ti3FeO15 with 4 mol% ytterbium substitution exhibited a significantly improved Curie temperature (TC) of 771 °C.•Bi5Ti3FeO15 with 4 mol% ytterbium substitution demonstrated stable electromechanical properties up to 300 °C.