Ferroelectric polarization reversal in potassium dihydrogen phosphate and potassium dideuterium phosphate as monitored by switching current

Ferroelectric polarization reversal in potassium dihydrogen phosphate (KDP) and potassium dideuterium phosphate (DKDP) was studied by applying electric field pulses and monitoring the current which flowed in a series resistor (switching current). Switching currents were recorded as a function of electric field (50V/cm to 1000V/cm for KDP; 50V/cm to 3000V/cm for DKDP) at various temperatures (88K to 120K for KDP; 167K to 207K for DKDP). The data was fit (with excellent results) to a modification of the Johnson-Mehl-Avrami model of nucleation and growth which had previously not been applied to this system. The shape of the switching curve differed significantly from the only previous report. In the case of DKDP the present report is believed to be the first results presented and certainly the first time such an analysis has been made. The switching proceeded faster (provided large enough fields were applied) than previously suspected. A parameter from the fit (characteristic time) was found to have a power law dependence on electric field in both KDP and DKDP which had not previously been reported. The exponent of the power law relation, in turn, depends on temperature.