Use of Amorphous Oxides as High Temperature Dielectric Material in Wound Capacitors (PREPRINT)

Capacitors that perform well at temperatures exceeding 200C and have energy densities in excess of 5 Jcm are an enabling technology for many applications in automotive, geophysical exploration, aerospace, and the military. To address this need Nanohmics has been examining the use of amorphous oxides as the dielectric material for high energy density, temperature-stable rolled film capacitors. Such capacitors can be fabricated by depositing 0.3 -0.7 m films on both sides of a thin metallized flexible substrate to form dielectric-coated electrodes. The two coated electrodes can then be rolled together into a cylindrical shape to produce a capacitor. Capacitors fabricated using amorphous silicon dioxide as the dielectric have been shown to have stable capacitance, dissipation factor, and breakdown threshold over a wide temperature range. Nanohmics is evaluating other amorphous oxide dielectric materials that have a higher dielectric constant in order to improve the energy density. These materials include hafnium dioxide and zirconium dioxide. Initial results indicate that the capacitance for these other materials can be higher but breakdown voltage and dissipation factor is sacrificed.