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The d.c. conductivity of poly(vinyl alcohol) hydrogels and ferrogels, cross-linked with borax, has been studied using two-probe resistance measurement method as a function of cross-linker and dopant concentrations. The availability of charge carriers (i.e. unbound borate ions and free sodium ions) in these matrices is seen to vary with cross-linker and dopant concentrations. Increase in borax concentration leads to the rise in d.c. conductivity values. Enhancement in the carbonyl iron dopant proportions, at unchanged borax concentrations, causes a decrease in the conductivity. This behaviour is explained on the basis of structural modifications introduced within the network matrix owing to the variations in cross-linker and dopant concentrations. [ABSTRACT FROM AUTHOR]

The sodium borate glasses doped with different CuO content (70B 2 O 3 ˗30Na 2 O˗xCuO with x = 0, 2, 4, 6 and 8 mol%) have been prepared using the conventional melt-quenching technique. The amorphous nature of the prepared samples has been identified by X-ray diffraction (XRD). The experimental and theoretical density, the molar volume, and the oxygen packing density have been defined. The effect of CuO incorporation into the 70B 2 O 3 ˗30Na 2 O glass base on the electrical and dielectric properties has been studied. The D.C. electrical parameters have been measured in the temperature range 323˗483 K, while the dielectric parameters have been measured in the temperature range 333˗483 K and the frequency range 10−1˗ 107 Hz. The D.C. electrical conductivity increases while the activation energy decreases by increasing CuO content (mol%). The conduction type is ionic which CuO inserts into the glass structure as a glass modifier. The A.C. study reveals that all investigated glasses obey the correlated barrier hopping model (CBH). Moreover, the dissipation factor peaks indicate the glasses' relaxation nature which has been further analyzed from the real and imaginary parts of the electric modulus. • The pure and CuO-doped sodium borate glasses have been prepared using the conventional melt-quenching technique. • The XRD analysis confirms the amorphous nature of the glasses. • The activation energy of the glass decreases with increasing CuO content (mol%) from 0.895 to 0.730 eV. • The A.C. studies demonstrate that the investigated glasses obey the correlated barrier hopping (CBH) model. • The presence of a peak in the frequency dependence of tan δ for all samples indicates the relaxation nature of these glasses. [ABSTRACT FROM AUTHOR]