Thickness Dependence of BaTiO3 Switching Time

The ferroelectric switching time of barium titanate single crystals has been measured at room temperature as a function of electric field and crystal thickness. The switching time was found to be independent of crystal thickness at high fields in disagreement with earlier work by Merz, who found the switching time proportional to thickness at the same high fields. At low fields the results are in substantial agreement with Merz and other previous work. At fields E greater than a threshold field of 1.4 (1+0.007 cm/d) kV/cm, where d is the crystal thickness, the switching time ts is given by 9E−1.4±0.1 (kV/cm)1.4 sec. Below this threshold the switching time is adequately represented by ts=0.8 exp3.5(1+0.007 cm/d) kV/cm/E μsec for d≳0.007 cm, but for d«.007 cm, the data are fitted better by ts=1.5×103 (Ed)−10.3±0.5 sec (V)10.3. Thus the data do not agree with the predictions of any known surface layer model of BaTiO3 switching.