Influences of ZrO2 on microstructures and properties of Li2O–Al2O3–SiO2 glass–ceramics for LTCC applications

In this work, Li2O–Al2O3–SiO2 (LAS) glass–ceramics for LTCC applications were prepared by the melt quench technique, and the influences of ZrO2 content on the microstructure, thermal, mechanical and electrical properties were investigated. XRD showed that the major crystalline phase was Li2OAl2O37.5SiO2 and the minor crystalline phases were ZrO2 and CaMgSi2O6. The formation of ZrO2 crystal phase with higher coefficient of thermal expansion (CTE) led to the increase of CTE value of LAS glass–ceramics, which was favorable for matching with silicon (3.1 × 10−6/°C). Moreover, it was found that the mechanical property enhanced markedly when the high thermal expansion phases generated in the glass–ceramic system with low CTE. The results indicated that the addition of ZrO2 was beneficial to promote the mechanical, thermal and dielectric properties. 3 wt% ZrO2-added LAS glass–ceramic sintered at 800 °C exhibited excellent properties: a high bulk density of 2.567 g/cm3, a high linear shrinkage of 20.08 %, a low CTE value (2.68 × 10−6/°C), a high flexural strength of 157 MPa, a low dielectric constant of 7.1, a low dielectric loss (tan δ) of 1.884 × 10−3 at 1 MHz, and a high resistivity (ρ > 1010 Ω cm).