Material design of two-phase-coexisting niobate dielectrics by electrostatic adsorption

Abstract

A material design process using electrostatic adsorption was proposed to synthesize composite ceramics with a two-phase-coexisting structure. Supported particles were fabricated by the electrostatic adsorption of (Na,K)NbO3–SrTiO3 (NKN–ST) nanoparticles on (Na,K)NbO3–Ba2NaNb5O15 (NKN–BNN) particles. NKN–ST and NKN–BNN were well dispersed with no aggregate in NKN–ST/NKN–BNN ceramics synthesized using the supported particles in comparison with ceramics synthesized using a mixture obtained by simply mixing NKN–ST and NKN–BNN powder. The temperature dependence of dielectric constant is closely related to the composite structure and the dielectric constant was stable in a wide temperature range from room temperature to 400 °C. Capacitance for DC bias was also insensitive to temperature in the range of 0–2 kV/mm, and the change rate of the capacitance was within ±5% in the temperature range from room temperature to 200 °C.