Characterization studies of potassium phosphotungstate glasses and a model of structural units
- 1 January 1989
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 85 (2) , 251-267
- https://doi.org/10.1039/f19898500251
Abstract
K2O–WO3–P2O5 glasses have been studied over a wide range of compositions. Their physical, thermal and spectroscopic properties, such as density, molar volume, microhardness, heat capacity, glass transition temperature and infrared special changes has been investigated. A structural model is presented to rationalize the experimental observations. According to this model, binary phosphotungstate glasses are built up of [WO6/2] octahedral and [POO3/2] tetrahedral units which share corners. Addition of K2O to binary phosphotungstates breaks the various linkages present in them. Consequently, a number of structural units are formed and the resulting glasses may be characterized by a network of polyhedra with different numbers of unshared corners. These structural units are consolidated into a structural phase diagram. The colours of these glasses, due to the presence of W5+ ions and their stabilization in the network as [W5+O6/2]– and [PO4/2]+ structural pairs, are also discussed.Keywords
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