• A new approach for understanding ion transport in glasses; example of complex alkali diborate glasses containing lead, bismuth and tellurium oxides

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    • Keywords


      Diborate glass; heavy metal ions; NBO–BO switching; lone pair electron.

    • Abstract


      Mechanism of ion transport in glasses continues to be incompletely understood. Several of the theoretical models in vogue fail to rationalize conductivity behaviour when d.c. and a.c. measurements are considered together. While they seem to involve the presence of at least two components in d.c. activation energy, experiments fail to reveal that feature. Further, only minor importance is given to the influence of structure of the glass on the ionic conductivity behaviour. In this paper, we have examined several general aspects of ion transport taking the example of ionically conducting glasses in pseudo binary, 𝑦Na2B4O7.(1−𝑦) M$_{a}$O$_{b}$ (with 𝑦 = 0.25–0.79 and M$_{a}$O$_{b}$ = PbO, TeO2 and Bi2O3) system of glasses which have also been recently characterized. Ion transport in them has been studied in detail. We have proposed that non-bridging oxygen (NBO) participation is crucial to the understanding of the observed conductivity behaviour. NBO–BO switching is projected as the first important step in ion transport and alkali ion jump is a subsequent event with a characteristically lower barrier which is, therefore, not observed in any study. All important observations in d.c. and a.c. transport in glasses are found consistent with this model.

    • Author Affiliations


      V C Veeranna Gowda1 C Narayana Reddy2 K J Rao3

      1. Department of Physics, Government College for Women, Chintamani 563 125, India
      2. Department of Physics, Maharani’s Science College for Women, Bangalore 560 001, India
      3. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India
    • Dates

  • Bulletin of Materials Science | News

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      Posted on July 25, 2019

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