Nonlinear Dielectric Materials and Processing for High-Energy-Density Capacitors

Active Signal Technologies proposes to develop novel nonlinear dielectrics based largely on solid solutions of substituted sodium bismuth titanate (NBT) with substituted lead magnesium niobate (PMN) to shift the NBT antiferroelectric phase into the ambient temperature range. The effects on dielectric properties of nano-scale processing, including the preparation of submicron powders and coating the particles with glass-forming ions, will be studied. Measurements of permittivity, loss, resistivity, polarization and strain will be performed as a function of electric field, and breakdown strength will be measured on K-squares and small lab prototype capacitors to provide input data for our model which calculates intrinsic energy densities of the dielectrics comparing nano with conventional processing. It is anticipated that the nano processing, which has been shown to enhance consolidation and increase breakdown strength, combined with the unique NBT-PMN compositions will yield high energy densities with very low dissipation factor. In parallel, the team will demonstrate engineering capability to build and test a large (12-kV, 0.5 & #956;F) low inductance module using a commercial, high-energy-density antiferroelectric dielectric. A smaller module will also be constructed with prototype fuse elements to prove that graceful failure mechanisms can be achieved while pulsing at 100-pps. BENEFIT: The availability of high-energy-density ceramic capacitors that exhibit graceful failure and can to scaled to large capacitances at high voltages will greatly reduce the size and weight of power-conditioning systems and directed energy weapons since capacitors are often the largest component of these systems. Additionally if the capacitors extend these properties to high temperatures then hybrid electric vehicle and energy exploration technologies will be positively impacted.