The sintering and dielectric properties modification of Li2MgSiO4 ceramic with Ni2+-ion doping based on calculation and experiment

Abstract

The microwave dielectric properties and sintering behavior of Li2(Mg1-xNix)SiO4 (x = 0.00–0.10) ceramics were researched with the help of first principle calculation and solid-state reaction experiment. The crystal structure, electron density, and formation energy were obtained through the density functional theory. The X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Network Analyzer were used in this study. The substitution of Ni2+-ion to Mg2+-ion could lower the densification temperature from 1250 °C to 1150 °C and improve the microwave dielectric properties of composite ceramics, demonstrated by the result of lattice parameters, bond population, electron density, and microstructure. A peak dielectric property of Li2(Mg1-xNix)SiO4 (x = 0.00-0.10) ceramics was achieved when x = 0.04 (εr = 5.69, Q×f = 28,448 GHz at 16 GHz, τf = −15.3 ppm/ °C) sintered at 1150 °C. Besides, LBBS glass was used as the sintering aid to lower the densification temperature from 1150℃ down to 900℃. The Li2(Mg0.96Ni0.04)SiO4 ceramic with 2 wt% LBBS sintered at 900 °C obtained excellent microwave dielectric properties, εr = 5.89, Q×f = 29,320 GHz (at 16 GHz), τf = −13.8 ppm/°C, and there was no chemical reaction between the composite ceramics and Ag. It’s a promising material for the applications of the millimeter-wave devices in the field of low temperature co-fired ceramics. Keywords: Low dielectric constant, LTCC, Microwave dielectric properties, DFT