High breakdown strength, multilayer ceramics for compact pulsed power applications

Advanced ceramics are being developed for use in large area, high voltage devices in order to achieve high specific energy densities (>10/sup 6/ J/m/sup 3/) and physical size reduction. Initial materials based on slip cast TiO/sub 2/ exhibited a high bulk breakdown strength (BDS>300 kV/cm) and high permittivity with low dispersion (/spl epsi//spl ap/100). However, strong area and thickness dependencies were noted. To increase the BDS, multilayer dielectric compositions are being developed based on glass/TiO/sub 2/ composites. The addition of glass increases the density (/spl ap/99.8% theoretical), forms a continuous grain boundary phase, and also allows the use of high temperature processes to change the physical shape of the dielectric. The permittivity can also be manipulated since the volume fraction and connectivity of the glassy phase can be readily shifted. Results from this study on bulk breakdown of TiO/sub 2/ multilayer structures with an area of 2 cm/sup 2/ and 0.1 cm thickness have measured 650 kV/cm. Furthermore, a strong dependence of breakdown strength and permittivity has been observed and correlated with microstructure and the glass composition. This paper presents the interactive effects of manipulation of these variables.