Accurate conductivity measurements, as a function of temperature (30–120° C) and
hydrostatic pressure (1× 10− 4–0· 5 GPa) have been performed on ionic conductive, xP2O5–
(1–x) Na2O, sodium phosphate glasses and on electronic conductive, xP2O5–(1–x) V2O5,
phosphovanadate glasses with x= 0· 4 and 0· 5. Isobaric variations for ionic conductivity with
temperature are characteristic of an activated mechanism for charge carrier formation and
migration. The associated activation enthalpy, ΔH*(around 0· 7 eV), is found to be pressure …

Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces, UMR
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France which interstitial cationic pairs, resulting from the auto-ionisation of the
macromolecular chain, seem to be responsible for cationic conductivity." The forma-tion of
an interstitial pair in glass may be seen as simi-lar to the formation of a Frenkel defect in an
ionic crystal. Consequently, and below the glass transition temperature, the ionic …