10F-5 Integrated Ultrasonic Transducers above 500°C

New piezoelectric composite materials, manganese doped sodium bismuth titanate (NBT+Mn)/lead zirconate titanate (PZT) and lithium niobate (LN)/PZT have been developed for ultrasonic transducer trials at operation temperature more than 500degC. Three kinds of piezoelectric powders, bismuth titanate (BIT), NBT+Mn, and LN, were dispersed into PZT sol-gel, and ~60 mum thick BIT/PZT, NBT+Mn/PZT, and LN/PZT films were deposited onto 26 mm thick titanium (Ti) substrates by sol-gel spray technique, respectively. Reflection echoes from Ti substrates were observed for each sample at various temperatures, from room temperature to above 500degC, and the signal amplitude change was monitored. LN/PZT films demonstrated the highest temperature stability among three materials. Using LN/PZT, broadband ultrasonic signals centered at 5.0 MHz with 25 dB signal to noise ratio were recorded at 700degC without depoling.