Sol–gel prepared bismuth titanate for high temperature ultrasound transducers

Bismuth titanate (BIT) ceramic was prepared via a sol–gel technique and characterised for use as a high temperature ultrasound sensor. Transducers were prepared as both a pressed ceramic disc and a thick film screen printed on a stainless steel shim. Platinum paste was used as an electrode, and oil bath poling at 120 kV cm−1 and 140 °C was done to align dipoles within the samples. The thermal stability of the BIT with regards to the piezoelectric coefficient was examined. Through-thickness ultrasound measurements were made on aluminium and mild steel blocks, and also on a stainless steel pipe at temperatures of up to 230 °C.