Ferroelectric Switching Time Measurements

A simple method is described for determining field-induced polarization reversal times in ferroelectrics ranging from seconds to nanoseconds without the use of an oscilloscope. The procedure consists of 1) setting some selected reference state of polarization, preferably by recording a hysteresis loop which is terminated at the reference state, 2) applying a pulse field of known amplitude and duration to reverse a portion or all of the polarization, and 3) tracing a new hysteresis loop. The difference in polarization state between the starting point of the second loop and the termination point of the first is the amount of polarization switched by the pulse field. Data consist of charge densities ⋀Pr switched by the pulse fields of various amplitudes E and durations t. From ⋀Pr versus E plots, the field corresponding to half-switching of the polarization is read for each pulse length applied and a log/log plot of the half-switching time t1/2 versus E is constructed. These log/log plots for lead zirconate-titanate ferroelectrics generally yield, each, three linear segments in which, with increasing field, t1/2 is proportional to E-ß, E-γ, and E-δ and ß>γ>δ.