Simultaneous achievement of high performance and low sintering temperature in ultra-high Curie temperature La2Ti2O7 ceramics by V2O5 additive

Abstract

La₂Ti₂O₇ (LTO) is one of the promising piezoelectric materials used in the high-temperature region due to the remarkable T_C of 1460 °C. However, LTO ceramics face challenges such as a low piezoelectric constant d₃₃ and a high sintering temperature. In this work, V₂O₅ is used as a sintering aid to modify the LTO ceramics. The addition of V₂O₅ reduces the sintering temperature of the LTO ceramics from 1500 °C to 1400 °C, enhances the piezoelectric constant d₃₃ of the LTO ceramics from 1.5 pC N⁻¹ to 5.6 pC N⁻¹, achieving a substantial enhancement to 373% of the pristine LTO ceramics, and maintains a high Curie temperature above 1370 °C. Benefiting from the increased density, the high-temperature resistivity of the modified LTO ceramics is also improved. In addition, the dynamic mechanical analysis reveals that V₂O₅ significantly enhances the thermal stability and high-temperature rigidity of LTO ceramics, as evidenced by the reduced variation in elastic modulus from 100 °C to 500 °C. Various characterizations indicate that broken local symmetry plays an important role in softening elasticity and enhancing the piezoelectricity after the addition of V₂O₅. This study provides valuable insights for optimizing ultra-high temperature ceramic materials, offering significant practical applications.