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 growing 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 εrmax temperature, and the associated tan δ dispersion peak, are each displaced to low temperatures such that a very favourable combination of low dielectric loss, tan δ < 0.015, from −60 to 310 °C and stable εr, ∼500 ± 15% from −70 to 300 °C (1 kHz data) are demonstrated. Hence the x = 0.2 material achieves stable εrand low loss over the technologically important target temperature range, −55 to 300 °C.