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High Temperature Sodium Bismuth Titanate Capacitors – A New Product Realized
ISSN: 1946-3855, e-ISSN: 1946-3901
Published November 11, 2008 by SAE International in United States
Event: Power Systems Conference
Citation: Bridger, K., Cooke, A., Schulze, W., Weigner, J. et al., "High Temperature Sodium Bismuth Titanate Capacitors – A New Product Realized," SAE Int. J. Aerosp. 1(1):876-882, 2009, https://doi.org/10.4271/2008-01-2863.
This paper describes the development of a lead free, high temperature ceramic capacitor material having the base composition of (Na0.5 Bi0.5) TiO3. The goal is to modify this structure to create a material that has the relative permittivity of barium titanate with extended X7R-like properties to 250°C - an X14R. After an extensive compositional and theoretical modeling investigation a composition was selected and capacitors developed. The dielectric has a 1-kHz relative permittivity of ∼1200 with <±15% variation from -25 to +250°C and <5% loss from -55 to +250°C. These capacitors also have very low voltage coefficients, indeed they are positive at the low end of the temperature range, resulting in a combined TC-Vc capacitance variation 0%/-25% of nominal from -55 to +200°C with applied voltage stress from 20 to 260 V/mil.