Effect of K2O on the glass structure, crystallization behavior, and properties of non-stoichiometric cordierite glass-ceramics

Glass-ceramics with α-cordierite as the primary crystalline phase were prepared via solid-state sintering with varying K 2 O additions, utilizing perlite tailings as the starting material. The effects of sintering temperature and K 2 O addition on the glass structure, crystallization behavior, microstructure, properties and crystallization kinetics were systematically investigated. The results indicated that an appropriate addition of K 2 O could prevent the formation of μ-cordierite intermediate phase and promote the direct precipitation of α-cordierite, thereby effectively shortening the overall crystallization pathway. This addition also lowered the densification temperature of the glass-ceramics and improved their mechanical and dielectric properties. Crystallization kinetics analysis revealed that K 2 O addition significantly reduced the crystallization activation energy of α-cordierite, while remaining the bulk nucleation and one-dimensional crystal growth mechanism. The α-cordierite glass-ceramics with 0.7 wt% K 2 O addition sintered at 850 °C exhibited the optimal comprehensive properties: high flexural strength of 145.7 MPa, low dielectric loss of 1.80 × 10 −2  at 10 MHz, and suitable coefficient of thermal expansion of 3.71 × 10 −6  K −1 . These properties highlight the potential of this glass-ceramic as a promising candidate for low-cost LTCC substrate materials.