A ferroelectric loop tracer and its applications

In the usual technique for the display of ferroelectric hysteresis loops, the specimen is excited from a sinusoidal a.c. voltage source, signals proportional to D and E are derived and these are respectively applied to the vertical and horizontal deflection plates of a cathode ray oscilloscope. Ordinarily, the frequency of excitation is 60 c.p.s., the choice being purely one of convenience. Actually, it would be preferable to obtain a plot of the quasi-static loop except where one is specifically interested in frequency dependent hysteresis effects. Quasi-static loops can be obtained by a point by point ballistic method, but this is a tedious procedure and there is always the uncertainty in distinguishing between the effects of the polarization current and the conduction current.