NaNbO3–BaTiO3–Ba0.93Ca0.07TiO3 ceramic composites for temperature stable X8R rated dielectrics

X7R rated dielectrics with room temperature relative permittivity (εr) of ∼2000 are produced as ceramic–ceramic composites based on a ferroelectric BaTiO3 matrix (BT, Curie Temperature, Tc = 122 °C) and a relaxor-ferroelectric Na0.6Ba0.4Nb0.6Ti0.4O3 filler (Tmax = −135 °C at 250 kHz) in a respective 80:20 wt. % mass fraction. X8R rating is achieved when the composite is formed with a Ba0.93Ca0.07TiO3 (BCT, Tc = 129 °C) matrix phase instead of BT. The enhancement from X7R to X8R performance is attributed to creating a broader εr peak at ∼121 °C due to a wider distribution of A-site cations in the composite, as opposed to an increase in Tc of monolithic BCT.