Structure and property of multicomponent germanate glass containing Y 2 O 3

CaO–BaO–Al₂O₃–SiO₂–GeO₂ glasses doped with 0·00–16·67 wt-% Y₂O₃ have been prepared by conventional melt quenching method. The influence of Y₂O₃ addition on the properties and structure of the glasses has been investigated. The results show that, with the introducing of Y₂O₃, the density, glass transition temperature and thermal expansion coefficient of the glass increase but the chemical durability declines. In addition, compared with the glass without Y₂O₃, the bend strength of the glass including 4·76 wt-% Y₂O₃ increased from 54 to 110 Mpa. The possible mechanism is that yttria acts as a network former in the structure and makes the island shape network unit repolymerisation by forming Ge–O–Y bond. The absorption strength caused by hydroxyl vibration decreased up to completely disappearance as the Y₂O₃ content increased continuously. The introducing of yttria in the composition causes the conversion from four coordination to higher coordination germanium, which decreases non-bridge oxygen (NBO) and weakens hydroxyl characteristic absorption.