Switching Behavior of Ferroelectric Bi4Ti3O12

Abstract

The switching behavior of single‐crystal ferroelectric Bi₄Ti₃O₁₂ has been determined at room temperature. The switching time for fields from 4 to 14 kV/cm can be expressed as t_s = 1.32×10⁻³ exp [61.6 (kV/cm)/E] μsec. For fields in the range 3 to 4 kV/cm, partial switching occurs; for fields less than 3 kV/cm, switching does not occur. In the region of exponential dependence, t_s was measured as a function of E by the direct observation of switching current pulses. For fields in the region of incomplete switching, the behavior was determined by measuring the fraction of polarization reversal as a function of field for different voltage pulse widths. A family of curves with pulse widths ranging from 100 μsec to 5 h clearly shows a switching threshold at a field of approximately 3 kV/cm. Oscilloscope photographs reveal initial hysteresis loops that possess a field axis bias which rapidly anneals to give a nearly symmetrical loop. The dependence of switching time on the frequency of the applied switching voltage indicates that the bias effect has a relaxation time extending from less than 5 msec to several minutes or longer. The unusual switching properties are explained in terms of the rapidly changing bias. The source of the internal bias is not determined in this investigation.