Rare-earth praseodymium-substituted Bi5Ti3FeO15 exhibiting enhanced piezoelectric properties for high-temperature application

Owing to their exceptional piezoelectric effects, piezoelectric materials play a crucial role in high-end technologies and contribute significantly to the national economy. Bismuth layer-structured ferroelectrics (BLSFs) possess high Curie temperatures, making them a focal point of research in high-temperature piezoelectric sensor devices. However, their poor piezoelectric performance and low direct-current (DC) electrical resistivity hinder their effective deployment in high-temperature applications. To overcome these shortcomings, we employed composition optimization by partially substituting bismuth ions with rare-earth praseodymium ions. This approach enhances the piezoelectric performance and improves the DC electrical resistivity by preventing the loss of volatile bismuth ions and stabilizing the bismuth oxide layer (Bi₂O₂)²⁺, thereby reducing the concentration of oxygen vacancies. Consequently, we achieved a large piezoelectric constant d₃₃ of 23.5 pC/N in praseodymium-substituted Bi₅Ti₃FeO₁₅, which is three times higher than that of pure Bi₅Ti₃FeO₁₅ (7.1 pC/N), along with a high Curie temperature T_C of 778 °C. Additionally, the optimal composition of 4 mol% praseodymium-substituted Bi₅Ti₃FeO₁₅ exhibits good thermal stability of electromechanical coupling characteristics up to 300 °C. This study holds promise for a wide array of high-temperature piezoelectric applications and has the potential to accelerate the development of high-temperature piezoelectric sensor technologies.