6MPI0301: Losses in piezoelectric materials.

Abstract

The losses associated with piezoelectric behaviour have been investigated, by measurements at frequencies and fields where extrinsic contributions play a significant role. The study concentrated on measurements in the quasi static frequency range 0.1 to 1kHz, rather than through resonance methods. The piezoelectric loss was measured using a standard Berlincourt type setup modified to enable the phase angle between the applied stress and charge output to be analysed. The mechanical loss was also investigated by measureing the phase angle between applied stress, and induced strain in a strain gauged piezoceramic sample. The piezoelectric loss showed an increase with increasing AC amplitude for hard and soft. However, the increase in loss seen at low frequencies was seen in all materials including Lithium Niobate, and it was concluded that this was an experimental artefact. The elastic loss measurements were more difficult to quantify because of bending of the sample, giving rise to arbitrary initial phase angles.