Phenomenological description of piezoresistivity in semiconducting perovskite ferroelectrics

An expression has been developed for the hydrostatic piezoresistive effect in semiconducting perovskite ferroelectrics. Numerical solutions are presented for a spectrum of surface-state densities in semiconducting barium titanate with a positive temperature coefficient of resistivity. The computations were carried out for some postulated pressure and temperature levels, above the ferroelectric-paraelectric anomaly temperature $T_c$. A comparison to experimental data is given.