IR and Raman investigation on the structure of (100- x)B 2O 3- x[0.5 BaO–0.5 ZnO] glasses

Abstract

Glasses with molar composition of (100- x)B 2O 3- x[0.5 BaO–0.5 ZnO], x=40, 50, 60, 70 were prepared from the melts of ZnO, BaCO 3 and H 3BO 3 mixture. The structure and thermal behavior were characterized by IR and Raman spectroscopy, DSC and Dilatometer. The investigation shows that the transition of the structural unit [BO 4] (B IV) to [BO 3] (B III) happens when BaO and ZnO content x increases in the borate glass, resulting in fewer B III–O–B IV bonds and more B III–O–B III bonds. At the same time, the diborate groups, which are found to be the predominant structural group of the glass with high B 2O 3 content, gradually changes into ring-type metaborate, pyro- and orthoborate groups. With increasing ZnO and BaO content x, the glass transition temperature ( T g) and the softening point ( T f) decreases, while linear expansion coefficient ( α) increases, that comes from the weakening of the glass network.