engleski

Structure and electrical properties of Li2O-ZnO-P2o5 glasses

The effect of compositional changes observed by replacing ZnO with Li2O in xLi2O(40-x)ZnO-60P2O5, (0<x<40), glasses on the electrical and dielectric properties have been investigated. Glasses were analyzed by different thermal analysis (DTA), Raman and Impedance Spectroscopy in the frequency range from 0.01 Hz to 4 MHz and temperature range from 303 to 473 K. The addition of Li2O up to 20 mol%, give rise to the discrete reorganization of phosphate cross-linked network with formation of the isolated Li-O polyhedra. This initial reconstruction of predominantly metaphosphate structure is consistent with the observed decrease in the Tg, electrical conductivity and dielectric permittivity. Further addition of Li2O content up to 40 mol%, results in the beginning of depolymerization of phosphate network with breaking of the P-O-P bonds and conversion of the Q3 to Q2 units. The initial depolymerization, not sufficiently balanced, causes a drop in conductivity and dielectric permittivity due to the blocking of the conduction pathways for Li+ ions. With increasing Li2O content up to 40 mol% the values of electrical conductivity increase for five orders of magnitude indicating ionic conductivity. This increase coincides with an increase in the ionic interconnection of the network and an increase in the strength of phosphate structure.

Li-phosphate; electrical conductivity; dielectric properties

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