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Chemical Structures of Glasses of the NaBO2-NaPO3System

1967; Oxford University Press; Volume: 40; Issue: 1 Linguagem: Inglês

10.1246/bcsj.40.110

1348-0634

Terumasa Nakamura, Shigeru Ohashi,

Glass properties and applications

Abstract Glasses of the NaBO2-NaPO3 system with P/B ratios in the range from 1.0 to 98.9 have been prepared from sodium metaphosphate and sodium metaborate by quenching melts of their mixtures. By the paper chromatographic analysis and the pH titration of the solutions of the glasses, it has been found that the glasses have the chain and branched structures consisting of P–O–P, P–O–B and B–O–B linkages. On the assumption that the glasses are composed of polypohsphate and polyborate chain blocks and branched BO3 units, the theoretical treatment has been made on the compositions of these blocks and units and compared with the experimental data. It has been concluded that (1) the glass with a P/B ratio of unity, i. e., a mole fraction of sodium metaphosphate m is 0.5, may be composed of chains of the P–O–P, P–O–B and B–O–B linkages, (2) with the increase of P/B ratios, the amount of the B–O–B linkages decreases, while the amount of the branched BO3 units increases and (3) in the glasses with P/B ratios larger than 4.0 (m>0.8), all boron atoms are present as the branched BO3 units.