Microstructure and Raman spectra analysis of [(Zn0.8Mg0.2)1-xNix]2SiO4 microwave dielectric ceramics featuring low relative permittivity and low dielectric loss

Abstract

A solid-state reaction method was successfully employed to synthesize [(Zn_0.8Mg_0.2)_1-xNi_x]₂SiO₄ microwave dielectric ceramics by partially substituting [Zn_0.8Mg_0.2]²⁺ with Ni²⁺ ions. XRD analysis indicated that the proportion of the primary Zn₂SiO₄ phase decreases with increasing Ni²⁺ content, while the secondary MgNi(SiO₄) phase becomes predominant. This phase transition contributes to a reduction in dielectric loss. The sintering behavior, phase composition, microstructure, and microwave dielectric properties of the ceramics were systematically investigated. The incorporation of Ni²⁺ ions lowered the optimal sintering temperature from 1325 to 1400 °C. SEM analysis revealed that an optimal Ni²⁺ substitution level enhanced the grain density within the [(Zn_0.8Mg_0.2)_1-xNi_x]₂SiO₄ ceramic matrix. The relationship between Q × f and the average grain size as well as grain uniformity was analyzed. The trend of τ_f is primarily governed by the total V_izn-o and E_zn-o. Additionally, the relationship between lattice vibrations, Raman shifts, and dielectric properties was investigated using Raman spectroscopy. Certainly, the [(Zn_0.8Mg_0.2)_0.8Ni_0.2]₂SiO₄ ceramic, sintered at 1325 °C, exhibits an exemplary set of microwave dielectric properties: an εr value of 6.8, a Q × f value of 27,185 GHz, and a τ_f value of − 37 ppm/ °C.