| Origin of Conductivity Threshold in the Solid (2009) | |||||||||||||
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| glasses increases to display a step-like jump of nearly five orders of magnitude in the narrow composition range, W7 IS7 range. To elucidate the origin of this threshold behavior, we have now examined the molecular structure of these glasses in modulated-differential scanning calorimetry (MDSC) and Raman scattering experiments. Our MDSC results reveal bimodal glass transition temperatures (T�s), a low-T � and a high-T � in the U7 RH7 range but unimodal ones outside this range. The low-T � phase bears a similarity to that of the stoichiometric glass at a I P, or AgAsS P, and we identify it with a Ag-rich phase formed in these glasses once U7. The Ag-rich phase is thought to percolate near W7, and to contribute to the large jump in conductivity of the glasses. The high-T � phase represents a semiconducting AsPSQ glass phase alloyed with a few mole percent of Ag P S, and it displays a reversibility window in the V7 IQ7 range. The semiconducting phase becomes elastically flexible once IQ7. Softening of the high-T � phase lowers Ag C ion migration energies and also contributes to the conductivity threshold. Index Terms—Macroscopic phase separation, modulated DSC, Raman scattering, self-organization, solid electrolyte glasses. I. | |||||||||||||
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