High-temperature dielectrics in CaZrO3-modified Bi1/2Na1/2TiO3-based lead-free ceramics

Materials in two composition regimes, Bi1/2Na1/2TiO3–BaTiO3–CaZrO3 (BNT–BT–CZ) and Bi1/2Na1/2TiO3–BaTiO3–K0.5Na0.5NbO3–CaZrO3 (BNT–BT–KNN–CZ), were synthesized via the mixed oxide route and their structural, dielectric and electrical properties were investigated. CZ was identified to render the two local maxima in permittivity more diffused. This resulted in temperature-insensitive relative permittivity spectra with average values from ∼470 up to ∼2300 and operational windows of at least ∼400 °C with less than 15% of variation in the temperature range from −100 up to above 500 °C. Moreover, loss factors are below ∼10% and RC constants range from ∼0.03 s up to ∼4 s at 300 °C. The materials of current investigation are highly attractive for developing capacitors of wide temperature usage.