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 Li_5.48Mg_0.74Ti_7.26O₁₈, 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: \({\varepsilon }_{\text{r}}\) of 7.97, Q value of 1305 (10 GHz), flexural strength of 259 MPa, CTE value of 10.2 ppm/°C, and \({\tau }_{\text{f}}\) value of − 13 ppm/°C. The LMZBS/TiO₂ composites are suitable for LTCC application with match-well Ag electrodes.