Dielectric ceramic with stable relative permittivity and low loss from −60 to 300 °C: A potential high temperature capacitor material

A new dielectric is described that meets the industry-standard lower limiting temperature of stable performance, -55 °C whilst extending the upper limit to 300 °C, with low dielectric loss, as required for the developing high-temperature electronics sector. The combined substitution of Sr and Bi ions on A sites, and Mg and Zr ions on B sites of the ABO3 perovskite solid solution (1-x)Ba0.6Sr0.4Zr0.2Ti0.8O3-xBi(Mg0.5Ti0.5)O3, flattens the εr -T response. At composition x = 0.2 the εr max temperature , and the associated tan δ dispersion peak, are each displaced to low temperatures such that a very favourable combination of low dielectric loss, tanδ < 0.015, from -60 to 310 °C and stable εr, ~ 500 ± 15 % from -70 to 300 °C (1 kHz data) is demonstrated. The x = 0.2 material achieves stable εr and low loss over the technologically important target temperature range, -55 to 300 °C