Investigation on glass-forming ability,Flexural strength and microwave dielectric properties of Al2O3-doped LMZBS glasses

Abstract In this work, a new high flexural strength microwave dielectric material for LTCC applications, (1-x) Li 2 O MgO ZnO B 2 O 3 SiO 2 -xAl 2 O 3 (x = 1–10 wt %) (LMZBSA) glass-ceramics, was prepared by conventional solid-state reaction method. The effects of Al 2 O 3 -doped Li2O MgO ZnO B 2 O 3 SiO2 (LMZBS) glass on its glass-forming ability (GFA) and activation energy were investigated by Dietzel, Saad-Paulin methods and Kissinger model, respectively. Comparing the undoped sample with the 10 wt % of Al 2 O 3 -doped LMZBS glass the parameters of ΔT and S which characterize the GFA increase by 35% and twice, respectively. Meanwhile, the addition of Al 2 O 3 will reduce the activation energy, making initial crystallization easier. And then the impact of Al 2 O 3 on the phase composition, flexural strength and microwave dielectric properties of LMZBSA glass-ceramics was studied systematically. It shows that the content of Al 2 O 3 has a great influence on the flexural strength of LMZBSA glass-ceramics, and different composition is responsible for its microwave dielectric properties. LMZBSA glass-ceramics with 5 wt % Al 2 O 3 sintered 2 h at 900 °C showed the highest relative density (96.41%) and flexural strength (σ = 190 MPa), optimum microwave dielectric properties ( e r  = 6.8, Q × f  = 12500 GHz, τ f  = −45 ppm/°C).