Experimental and theoretical characterization of an antiferroelectric ceramic capacitor for power electronics

Abstract

Capacitance-voltage (C-V) measurements up to 800 VDC were made on a modified lead-zirconate (PbZrO/sub 3/) 20-layer multilayer ceramic (MLC) antiferroelectric power-electronic capacitor, with large energy-density storage capability. For these a precision impedance analyzer was used, in conjunction with a high-voltage capacitor dc-bias circuit configured for voltage-isolation from the analyzer input. A peak effective permittivity /spl epsiv/ /spl sim/ 4300 was derived at the capacitance peak of 133 nF at 400-V dc-bias, yielding an energy density storage of /spl sim/0.5 J/cc in the device volume of 0.022 cc. Modeling of the experimental C-V response was applied to three conceptual series-connected capacitance regions within each grain and grain-boundary region of the MLC. The equivalent capacitance component for the first region was derived from the voltage-dependent polarizations within a ferroelectric and/or antiferroelectric grain. This involved application of differing Langevin functions for modeling the ferroelectric and antiferroelectric polarizations. That for the second region related to the voltage and frequency dependence of the equivalent p-n junction capacitance at opposite sides of a grain-boundary and compensation-region, with Debye-type relaxation constants relating its frequency dependence. The third capacitance region was associated with the insulator-barrier region itself. Agreement between experimental and theoretical C-V-f responses was considered to be good, in view of the number of modeling parameters and variables employed.