Temperature-stabilized novel high-entropy microwave dielectric  (Mg1/2Zn1/2)0.4+xLi0.4(Ca1/2Sr1/2)0.4-xTiO3 ceramics

In this work, a series of high-entropy ceramics which nominal composition (Mg1/2Zn1/2)0.4+xLi0.4(Ca1/2Sr1/2)0.4-xTiO3 (0 ≤ x ≤ 0.4) have been successfully synthesized using the conventional solid-phase method. The (Mg1/2Zn1/2)0.4+xLi0.4(Ca1/2Sr1/2)0.4-xTiO3 ceramics were confirmed to be composed of the main phase (Zn, Mg, Li)TiO3 and the secondary phase Ca0.5Sr0.5TiO3 by XRD, Rietveld refinement and EDS analysis. The quality factor (Qf) of the samples is inversely proportional to the content of the Ca0.5Sr0.5TiO3 phase, and it is influenced by the density. The secondary phase and molecular polarizability (αT) have a significant impact on the dielectric constant (εr) of the samples. Moreover, the temperature coefficient of resonant frequency (τf) of the samples is determined by the distortion of [TiO6] octahedra and the secondary phase with a positive τf value. (Mg1/2Zn1/2)0.4+xLi0.4(Ca1/2Sr1/2)0.4-xTiO3 ceramics achieved ideal microwave dielectric properties (εr = 17.6, Qf = 40,900 GHz, τf = -8.6 ppm/°C) when x = 0.35. Therefore, (Mg1/2Zn1/2)0.4+xLi0.4(Ca1/2Sr1/2)0.4-xTiO3 ceramics possess the potential for application in wireless communication, and a new approach has been provided to enhance the performance of microwave dielectric ceramics.