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Paper on "Manifestation of Site Energy Landscapes for Ion Transport in Borate Glasses" published in PCCP

V.H. Gunawan, M. Schäfer and K.-M. Weitzel

The potential energy landscape of a Li3B7O12 glass has been quantitatively studied by the Charge Attachment Induced Transport technique. The width of the populated part of the site energy distribution is 250 meV (FWHM).

While the potential energy landscape of single crystals can be characterized by a delta function for the distribution of energy minima (sites) and energy maxima (barriers), amorphous materials, e.g. glasses, are characterized by a distribution of site energies and barrier energies. For quantifying this energy landscape native Li ions in a glass have been replaced by foreign alkali ions (K, Rb, Cs) in a unidirectional transport experiment. The resulting concentration depth profiles have been quantified by means of secondary ion mass spectrometry (SIMS). Theoretical analysis of these profiles by means of the Nernst-Planck-Poisson (NPP) transport theory allows reconstruction of the populated part of the site energy distribution, whose width (FWHM) has been derived as 250 meV. The NPP formalism is demonstrated to be fully equivalent to an Onsager ansatz of irreversible thermodynamics reflecting that both fulfill the conditions of micro-reversibility.

Phys. Chem. Chem. Phys. accepted
Doi: https://doi.org/10.1039/D4CP00262H