Superior piezoelectric performance in holmium-substituted high-TC Bi5Ti3FeO15

High-temperature piezoelectric materials are essential for advanced sensor technologies, yet achieving both superior piezoelectric properties and a wide operating temperature range remains a persistent challenge. Bismuth titanate-ferrite (Bi5Ti3FeO15) is a promising candidate due to its notably high Curie temperature (TC) of approximately 761 degrees C. However, its low intrinsic piezoelectric response and limited poling efficiency, attributed to insufficient direct-current (dc) resistivity, have restricted its broader utilization. To address these issues, we explored compositional modifications by partially substituting A-site bismuth ions with holmium ions (Bi5- x Ho x Ti 3 FeO 15 , BTF-100xHo), aiming to enhance both piezoelectric performance and electrical resistivity. Comprehensive characterization was performed on the holmium-substituted ceramics, examining their crystal structure, microstructural attributes, and piezoelectric properties. Our findings reveal that the holmium- substituted Bi5Ti3FeO15 compositions exhibit significantly improved piezoelectric behavior in comparison to their unmodified counterparts. The optimized BTF-4Ho composition demonstrates a high piezoelectric coefficient (d33 = 23.1 pC/N) and an elevated T C of 795 degrees C. Moreover, the BTF-4Ho composition maintains stable electromechanical coupling across a wide temperature range, underscoring its potential for high-temperature sensor applications.