Polypyrrole and silver nanoparticles have been synthesized at 277 K by chemical route. Nanoparticles of polypyrrole-silver (PPy-Ag) composites were prepared by mixing polypyrrole and silver nanoparticles in different weight percentages. Dielectric properties as a function of temperature in the range from 300 K to 550 K and frequency in the range from 50 Hz to 1 MHz have been measured. Dielectric constant decreased with increase in frequency and temperature. Dielectric loss decreased with increase in frequency and increased with increase in temperature. Using dielectric data AC conductivity has been determined. Conductivity was found to be in the order of 10 −3 (Ω −1 m −1 ) and it increased with increase in temperature. Temperature variation of conductivity data has been analyzed in the light of Mott's polaron hopping model. Activation energy for conduction has been determined. Activation energy was determined to be in the order of meV and it has increased with increase in frequency and Ag nanoparticles content. This is the first time that PPy-Ag nanocomposites have been investigated for dielectric properties and AC conductivity and data analyzed thoroughly.

No abstract

No abstract

No abstract

Melt quenching technique has been adopted to synthesize a set of borotellurite glasses consisting of ZnO, Li2O, WO3 and Dy2O3, with a varied content of WO3. After confirming their amorphous nature by XRD, they were investigated for dielectric properties over a wide range of freqency and temperature. Observed variations in dielectric parameters with frequency, temperarure and composition suggests the presence of mobility of charge carriers, increase of loss due to ionic migration and involvement of dc conductivity. Single phase and conducting nature of the samples have been obtained by sketching cole-cole plots. DC conductivity estimated from impedance spectra indicated semiconducting nature and its activation energy increased with increase of WO3 concentration. Dielectric relaxation time and its thermal activation energy were determined independently from modulus and impedance and found that the former decreased with increase of temperature and the later increased with WO3 content. Master curves drawn for electric moduli revealed that relaxation mechanism in these glasses is temperature independent.