Excellent thermal stability and enhanced piezoelectric performance of Bi(Ni2/3Nb1/3)O3-modified BiFeO3-BaTiO3 ceramics

Lead-free piezoelectric ceramics with excellent piezoelectric performance and temperature stability are vital to stack up against PZT in various applications. Thus, xBiFeO(3)-(1-x)BaTiO3(BF-BT)-based ceramics with high Curie temperatures have drawn increasing attention. However, BF-BT based ceramics often show large leakage current due to the valence fluctuation of Fe ion. In this work, it is found that Bi(Ni2/3Nb1/3)O-3 (BNN) can suppress the valence fluctuation of Fe ions effectively. The effects of BNN on the crystal structure, morphology, and electrical properties of 0.69BF-0.31BT ceramics are investigated. For composition near morphotropic phase boundary of rhombohedral and tetragonal phases, the Curie temperature (T-c) is as high as 453 degrees C, and the piezoelectric constant (d(33)), planar electromechanical coupling factor k(p), and electric-field-induced strain Delta S can reach up to 191 pC/N, 31% and 0.236% (peak to peak), respectively. Moreover, these ceramics show excellent thermal stability. The d(33) of 100 pC/N is still maintained at about 360 degrees C and an ultrahigh strain (Delta S = 0.684%, peak to peak strain) is obtained at 190 degrees C. Our work illustrates that the BF-BT based ceramics can serve as potential candidates for sensor and actuator applications over a broad temperature range.

Automated summary

This study demonstrates that Bi(Ni2/3Nb1/3)O-3 (BNN) effectively suppresses the valence fluctuation of Fe ions in 0.69BF-0.31BT ceramics, resulting in high Curie temperatures and excellent piezoelectric performance. These ceramics have potential as candidates for sensor and actuator applications over a broad temperature range.