Network structure, crystallization behavior, and microwave dielectric properties of ZnO-B2O3 glass-ceramics with ZrO2 additions

Abstract

The effects of ZrO2 addition on the glass network structure, crystallization behavior and microwave dielectric properties of ZnO-B2O3 glass-ceramics were investigated. The introduction of ZrO2 decreases the connectivity of the superstructure in the borate glass network and thus affects the crystallization behavior of glass, leading to the transformation of the main crystalline phase from Zn4B6O13 to ZnB4O7 and Zn3B2O6. With the increase of ZrO2 content, the microstructure changed from the branch-like structure into the net-like structure. For the sintered glass-ceramics, the relative permittivity increased with the ZrO2 content, which relates to the decrease in the vibrational energy of the B-O bond. In addition, the glass-ceramic with 0.25 mol% ZrO2 exhibits the maximum Q×f value due to the low disorder of B3+ cations. The ZnO-B2O3 glass-ceramic with 0.25 mol% ZrO2 sintered at 660 °C for 5 h exhibits the optimum microwave dielectric properties with εr = 6.18, Q×f = 23,670 GHz, τf = −65 ppm/°C. The high Vickers hardness of 662 kgf/mm2 and excellent chemical compatibility with Ag electrode demonstrated that the glass-ceramic is a good candidate for ULTCC application.