Bond characteristics, microstructure, and microwave dielectric properties of Bi2O3–ZnO–B2O3 glass-ceramics with Li2O substitution.

The effect of Li 2 O substitution on the sintering behavior, lattice structure, microstructure, and microwave dielectric properties of ZnO–B 2 O 3 –Bi 2 O 3 glass-ceramics was studied by various amounts of Li 2 O to substitute ZnO. The substitution of Li 2 O decreases the glass network connectivity and thus decreases the sintering temperature of the glass. In the sintered glass-ceramics, the substitution of 0.2 mol % Li 2 O leads to the most significant lattice activation resulting in the glass-ceramic exhibiting the smallest cell volume of Zn 3 B 2 O 6 crystal and the microstructure with fine and uniform grains. The P–V-L theory is innovatively applied to glass-ceramic materials to characterize the variation in bond characteristics caused by lattice activation and it indicates that the 0.2 mol % Li 2 O substitution decreases the Zn–O bond ionicity and increases the lattice energy of the B–O bond, in the Zn 3 B 2 O 6 crystalline phase. The refinement of microstructure and the optimization of bond characteristics improve the microwave dielectric properties of glass-ceramics. The glass-ceramic with 0.2 mol % Li 2 O substitution sintered at 620 °C for 5 h exhibits excellent microwave dielectric properties of ε r ∼5.05, Q×f ∼15,383 GHz, τ f ∼ −6 ppm/°C and good chemical compatibility with Ag or Al electrodes, which is a favorable candidate for application in ULTCC substrate materials. [ABSTRACT FROM AUTHOR]