Graphene-Polyvinyl alcohol (PVA) nanocomposite films with thickness 120µm were synthesized by solidification of PVA in a solution with dispersed graphene nanosheets. Electrical conductivity data were explained as arising due to hopping of carriers between localized states formed at the graphene-PVA interface. Dielectric permittivity data as a function of frequency indicated the occurrence of Debye-type relaxation mechanism. The nanocomposites showed a magnetodielectric effect with the dielectric constant changing by 1.8% as the magnetic field was increased to 1 Tesla. The effect was explained as arising due to Maxwell-Wagner polarization as applied to an inhomogeneous two-dimensional,two-component composite model. This type of nanocomposite may be suitable for applications involving nanogenerators.

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Iron ion containing nanodimensional silica glass was grown within the 5 nm pores of mesoporous silica. The nanocomposite material showed ferromagnetic-like behavior at room temperature. This was ascribed to the presence of Fe2+ and Fe3+ ions within the nanodimensional glass phase and an antiferromagnetic superexchange interaction between them. The nanocomposite showed a large magnetodielectric coefficient (up to 51%) for a magnetic field of 1.7 T. The dielectric loss (tan δ) was found to be in the range 0.35 to 0.66. This was explained on the basis of Catalan’s model of space–charge polarization. From the theoretical fitting of experimental data, magnetoresistance of nanoglass phase was extracted to be 58% up to a magnetic field of 1.7 T.