The glass transition temperatures of phosphoric acids

ABSTRACT THE vitrification of phosphoric acids is relatively easy, a glass often being formed simply on cooling from the liquid melt. Special procedures, however, are required to crystallise

these materials. The glass transition temperature, _T_g, is the temperature above which there is relatively rapid molecular motion; below _T_g translational motion of molecules is

inhibited. In standard texts1 it is stated that the glass transition temperature of orthophosphoric acid, H3PO4, is −121 °C. The source of the determination is not always cited but it seems

to be that of Kobeko _et al._2 who determined _T_g from measurements of the temperature dependence of the electrical conductivity of phosphoric acid. Although published almost 40 yr ago

there does not seem to have been a more recent determination. We present here evidence from broad-line nuclear magnetic resonance (NMR) studies that the estimate of −121 °C for the glass

transition temperature of orthophosphoric acid is wrong. A discussion of the nterpretation of the electrical conductivity of phosphoric acid would be in appropriate beyond observing that

several different ionic or molecular processes may be responsible for the transfer of electrical charges. Thus, an unambiguous determination of a glass transition from such data may be far

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February 2023 REFERENCES * Toy, A. D. F., _The Chemistry of Phosphorus_, 482 (Pergamon, Oxford, 1975). Google Scholar  * Kobeko, P. P., Kuvshinskii, E. V., and Shishkin, N. J., _J. phys.

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York, 1972). Google Scholar  * Yates, M. J., thesis, Univ. Sheffield (1973). * Smith, R. J., thesis, Univ. Sheffield (1976). * Maklakov, A. I., and Pimenov, G. G., _J. polym. Sci.,

U.S.S.R._, 15, 123 (1973). Article  Google Scholar  * McCall, D. W., _Acc. chem. Res._, 4, 223 (1971). Article  CAS  Google Scholar  * Bondi, A., _Physical Properties of Molecular Crystals,

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AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Ceramics, Glasses and Polymers, The University of Sheffield, Sheffield, S10 2TZ, UK BRYAN ELLIS Authors * BRYAN ELLIS View author

publications You can also search for this author inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE ELLIS, B. The glass transition

temperatures of phosphoric acids. _Nature_ 263, 674–676 (1976). https://doi.org/10.1038/263674a0 Download citation * Received: 24 May 1976 * Accepted: 10 September 1976 * Published: 01

October 1976 * Issue Date: 21 October 1976 * DOI: https://doi.org/10.1038/263674a0 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get

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