Ferroelectric Ceramic Synthesis and Breakdown Characterization on Pulsed Condition Using High-Voltage Half-Sine Pulses of Microsecond Duration

Abstract

There are several high-power microwave sources nowadays, but few of them work with passive components. The nonlinear transmission lines (NLTLs) are high-power radio frequency (RF) generators that use nonlinear passive components, such as ceramic capacitors selected due to the material’s high dielectric strength and permittivity. The main requirement of these passive components is to provide a change in the capacitance or inductance as a function of the applied voltage. In this work, we synthesized ceramic capacitors with three different compositions based on barium, strontium, zirconium, and titanium, named by BSZT. Beyond that, the scanning electrode microscope (SEM) images of the samples measured the density and grain size via the intercept method. The 0.5BSZT composition results showed a grain size of the order of $34~\mu $ m and a density of the order of 5.75 g/cm3. The 20 and 30BSZT compositions showed grain sizes and densities of $0.8~\mu $ m and 5.5 g/cm3, respectively. The breakdown tests showed that samples with higher grain size have higher dielectric strength. The ferroelectric ceramic breakdown characterization was performed under pulsed conditions using high-voltage half-sine wave pulses with microseconds duration. For the 0.5BSZT composition, the average dielectric strength was about 10.33 kV/mm with a standard deviation of 3.88 kV/mm. We also measured the polarization as a function of the electrical field to determine recoverable energy storage density and the coercive field of the sample related to the material losses. The experimental constraints discussed about dielectric strength measurements avoid wrong interpretations of data acquisition.