Study of Ta ₂O ₅ for use as high temperature piezoelectric sensors

Acoustic sensors which can function at high temperatures have important potential uses. In this work we report on the deposition, characterization and qualitative assessment of piezoelectric behaviour of orthorhombic Ta ₂O ₅. It is shown that orthorhombic Ta ₂O ₅ belongs to the class 2 mm. XRD analysis of films annealed for 1 min., 10 min. and 1 hr at 800 °C and 900 °C reveal the formation of (0 0 1), (1 10 0) and (1 11 0) orientations at 800 °C, but the (1 10 0) increases at the expense of the other two as the annealing period is extended. At 900 °C the dominant orientations are (1 10 0) and (2 9 0). The piezoelectric effect is significantly stronger after annealing and the stronger piezoelectric effect does not correlate with the presence of (1 10 0) and (2 9 0) so much as with the absence of (0 0 1) and (1 11 0).