BiScO3-BiFeO3-PbTiO3-BaTiO3 high-temperature piezoelectric ceramic and its application on high-temperature acoustic emission sensor

Piezoelectric ceramic based high-temperature acoustic emission (AE) sensor is required urgently in the structural health monitoring of high-temperature fields. In this research, a series of 0.45(BiScxO3-BiFe1-xO3)-0.48PbTiO(3)-0.07BaTiO(3) (BScxFe1-x-PT-BT, n(Sc)/n(Fe) =0.4/0.6 - 0.6/0.4) ceramics with both high Curie temperature and large piezoelectric constant were presented. The structure and electrical properties of BScxFe1-x-PT-BT ceramics as a function of n(Sc)/n(Fe) have been systematically investigated. All the ceramics possess a perovskite structure, and the phase approaches from the rhombohedral toward the tetragonal phase with the decrease of n(Sc)/n(Fe). The BSc0.5Fe0.5-PT-BT and BSc0.55Fe0.45-PT-BT piezoelectric ceramics exhibit good piezoelectricity (d(33)=250-281 pC/N), high Curie temperature (T-C=430-450 degrees C) and excellent temperature stability. These improvements are greatly attributed to the balance between rhombohedral and tetragonal phase near morphotropic phase boundary with dense microstructure of ceramics. AE sensor based BSc0.5Fe0.5-PT-BT piezoelectric ceramic was designed, prepared and tested. The high-temperature stability of AE sensor was characterized through pencil-lead breaking with in situ high-temperature test. The noise of AE sensor is less than 40 dB, and the acoustic signal is up to 90 dB at 200 degrees C. As a result, AE sensors based on BScxFe1-x-PT-BT piezoelectric ceramics are expected to be applied into the structural health monitoring of high temperature fields.