Silver ion dynamics in Ag<SUB>2</SUB>S-doped silver molybdate-glass nanocomposites: correlation of conductivity and scaling with structure

This work reports the study of silver ion dynamics in Ag2S-doped silver molybdate-glass nanocomposites of compositions xAg2S-(1 - x)(yAg2O-(1 - y)MoO3). The volume fraction of crystalline phases in these glass nanocomposites increases with the increase of Ag2S content and considerably influences the dc conductivity. It is observed that a significant amount of volume fraction of crystalline phases for x ≥ 0.15 for the y = 0.20 series and for x = 0.20 for the y = 0.30 series causes the conductivity to decrease. The power law exponent has been obtained from ac conductivity spectra using the power law model and is observed to be almost constant at lower volume fraction of the nanocrystalline phases embedded in the glass matrix, but it decreases for samples with high crystalline volume fraction. The electric modulus data have been analyzed on the basis of the Havriliak-Negami (HN) equation. The Kohlrausch-Williams-Watts (KWW) stretched exponent β, obtained from modulus data, indicates a strong nonexponential relaxation. The scaling of the conductivity spectra reveals that the relaxation dynamics is independent of temperature but is dependent on compositions affected by the increased volume fraction of crystalline phases of the glass nanocomposites