Effect of ZnO content on microstructure, crystallization behavior, and thermal properties of xZnO-30B2O3-(65-x)Bi2O3-5BaO glass

Abstract

xZnO-30B2O3-(65-x)Bi2O3-BaO (x = 40–60 mol%) glasses were prepared by the melt quenching method. The microstructure, crystallization behavior, and thermal properties of the glasses were investigated. The results show that the samples with 40–55 mol% ZnO possess an amorphous structure after melting at 950 °C. When the ZnO content increases to 60 mol%, the sample possesses strip-shaped Zn3B2O6 crystals after melting at 950 °C, and becomes homogenous glass at 1050 °C. The thermal expansion coefficient (TEC) decreases from 10.294 to 7.43 × 10−6/°C when the ZnO content increases from 40 to 60 mol%. Both the glass transition temperature and glass softening temperature increase with increasing ZnO content. In addition, needle-shaped Bi2ZnB2O7 crystals are observed on the glass surface after annealing at crystallization temperatures for 1 h, and the amount of crystals decreases with increasing ZnO content. Furthermore, the weight loss ratio of the glasses increases gradually as the content of ZnO increases. After 48 h, the magnitude of weight loss value in 6 wt% of HNO3 or NaOH solution at 90 °C is 10−3 g/cm3∙min while it is 10−7 g/cm3∙min in deionized water.