Materials design with enhanced temperature stability of resonant frequency for high frequency application

Abstract

For low temperature cofired ceramic (LTCC) materials to achieve increase functionality, as well as low loss and moderate dielectric constant, it is essential to achieve the temperature stability of the resonant frequency. Facing several empirical approaches toward tuning the temperature coefficient of the resonant frequency (τf) through the formation of mixtures or a solid-solution between the two end members with opposite signs of τf, which result in higher dielectric loss, we took a closer look at the texture engineering that determines the anisotropic dielectric properties in barium niobate ceramics. We demonstrate the advantage of texture engineering for microwave dielectric properties including temperature stability by control of crystallographic orientation. Also, the monoclinic rare earth niobates are investigated as novel microwave dielectric materials. Furthermore, the stable τf of the rare earth niobates could be efficiently explained through the ferroelastic domain engineering related to phase transformation.