Structural Role of PbO in Li2O–PbO–B2O3 Glasses

✍ Scribed by Munia Ganguli; K.J. Rao

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 237 KB
• Volume: 145
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8221

✦ Synopsis

Thermal and spectroscopic studies have been carried out on a number of glasses with wide ranging compositions in the pseudoternary glass system Li 2 O+PbO+B 2 O 3 in order to understand the structural role of PbO in these glasses. Infrared, Raman, and 11 B MAS-NMR results indicate that PbO behaves as a network former in these glasses and is possibly incorporated in the network as [PbO 4/2 ] 2؊ units. The formation of [PbO 4/2 ] 2؊ units leads to the creation of neutral three-coordinated boron (B 0 3 ) which, in turn, leads to the reformation of four-coordinated boron (B ؊ 4 ) in the structure at the expense of two-coordinated (B ؊ 2 ) and singly coordinated (B 2؊ 1 ) boron atoms. The variations of glass transition temperatures (T g ) and molar volumes also support this model.