Piezoelectric measurements of granite as composite material using atomic force microscope

The piezoelectric vibrational amplitude of a granite sample was measured using an atomic force microscope (AFM) and a lock-in amplifier system. Other samples such as lead zirconate titanate (PZT) and quartz were used as piezoelectric standards, and soda glass was examined as a control to check the background noise level. The converse piezoelectric effect, in which the electric field induces the strain, gave an apparent piezoelectric coefficient of similar to 7.0 (+/- 0.1) x 10(-13) C/N for granite. The relative dielectric constant of granite was also obtained by measuring the vibrational amplitude and the phase difference at different frequencies. The value was in the order of 10(13) less than 1 Hz and decreased as a function of frequency.