Effect of TiO2 on the sintering temperature and dielectric properties of Li2O–MgO–ZnO–B2O3–SiO2 ceramic composites for LTCC applications

The effects of injecting TiO2 to a Li2O–MgO–ZnO–B2O3–SiO2 (LMZBS) microwave dielectric composite on sinterability, microstructure, crystalline phase, dielectric characteristics, mechanical characteristics, and coefficient of thermal expansion (CTE) were investigated. With the increase of TiO2 content, the main crystal orientation of the samples gradually changed from Li2MgSiO4 phase, Mg3B2O6 phase, and Mg2SiO4 phase to Li5.48Mg0.74Ti7.26O18, ZnTiO3 phase, and Mg2B2O5 and the densification temperature decreased, whisker-like crystal grains gradually increased, and the porous microstructure appeared at 15% TiO2. With the increase of TiO2 content, the densification temperature of LMZBS ceramics increases, and the dielectric constant increases with the increase of densification temperature. The CTE value decreases with the increase of titanium dioxide content, and the bending strength increases first and then decreases with the increase of titanium dioxide content. The composite with 10 wt% TiO2 content sintered at 900 °C exhibits superior performance: εr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\varepsilon }_{\text{r}}$$\end{document} of 7.97, Q value of 1305 (10 GHz), flexural strength of 259 MPa, CTE value of 10.2 ppm/°C, and τf\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\tau }_{\text{f}}$$\end{document} value of − 13 ppm/°C. The LMZBS/TiO2 composites are suitable for LTCC application with match-well Ag electrodes.