| Summary: | There has been recently a great progress in the development of dielectric capacitors for high temperature electronic applications. The design of lead-free ceramics with high dielectric permittivity, low dielectric loss and a limited variation of these parameters over a wide temperature range is still a big challenge. In this work, lead-free Bi0.35Na0.65–0.5xRb0.5xTi0.7Nb0.3O3 (x = 0–0.05) bulk ceramics were prepared using the solid-state reaction method. Upon Rb substitution, the variation of the dielectric permittivity was reduced substantially, in particular, at high temperature (over 200 °C). In addition, a low temperature coefficient of capacitance (TCC ≤ 10%) together with an ultra-low dielectric loss (tanδ ≤ 0.05) were achieved for the Bi0.35Na0.63Rb0.02Ti0.7Nb0.3O3 sample in the temperature range from −43 °C to 292 °C. The new relaxor-type ferroelectrics also possess the outstanding stability of the dielectric properties under high DC bias voltage, which makes them promising materials for high-performance capacitors of the next generation.
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