Showing papers by "Sampat Raj Vadera published in 2006"
TL;DR: In this article, the authors reported electrical conductivity and dielectric studies on the composites of conducting polyaniline (PANI) with crystalline semiconducting ZnS powder, wherein PANI has been taken as inclusion and Zn S as the host matrix.
Abstract: In the present paper, we report electrical conductivity and dielectric studies on the composites of conducting polyaniline (PANI) with crystalline semiconducting ZnS powder, wherein PANI has been taken as inclusion and ZnS crystallites as the host matrix. From the studies, it has been observed that the value of room temperature d.c. conductivity of the composites with volume fraction of PANI > 0.65 shows an unusual behaviour wherein, conductivity values of the composites exceed that of PANI itself with maximum value as high as 6 times that of PANI at the volume fraction of 0.85. A similar trend has also been observed for the real and imaginary parts of complex dielectric constant values of the composites. This unusual behaviour in the d.c. conductivity and dielectric properties has been attributed to the enhancement in the degree of crystallinity of PANI as a consequence of its interfacial interaction with ZnS matrix. The results of optical microscopy show coating of PANI all around the ZnS particles. The temperature dependent conductivity studies suggest the quasi one-dimensional VRH conduction in PANI as well as its composites with ZnS. FTIR and XRD studies have also been reported.
117 citations
TL;DR: A comparative study of complex dielectric properties has been carried out at the X-band of microwave frequencies of composites of barium titanate (BaTiO3) with two different polymer matrices: insulating polyaniline (PANI) powder (emeraldine base) and maleic resin this article.
102 citations
TL;DR: In this article, a colloidal precipitation method with capping agent polyvinylpyrrolidone has been used to synthesize 2.5-nm sized nanoparticles, which have been confirmed by x-ray diffraction and transmission electron microscope studies.
Abstract: ZnS : Mn nanophosphor has been doped with quencher impurity Ni using the colloidal precipitation method with capping agent polyvinylpyrrolidone. The formation of ~2.5 nm sized nanoparticles has been confirmed by x-ray diffraction and transmission electron microscope studies. Energy and time resolved photoluminescence spectra of the synthesized nanophosphors have been studied at room temperature. Photoluminescent spectra for ZnS : Mn, Ni show three peaks at 412 nm, 433 nm and 590 nm corresponding to Ni impurity, sulphide vacancies (Vs) and Mn impurity, respectively. The ZnS : Mn nanophosphor show typical nanosecond lifetimes for defect-related emission and millisecond lifetimes for Mn impurity-related emission. However, the ZnS : Mn, Ni samples showed lifetime shortening, with variation of dopant concentration for defect-related (420 nm) as well as impurity-related emission (590 nm), which is attributed to exchange interaction between Mn2+ and nearest neighbour Ni2+ impurities.
34 citations
TL;DR: In this article, meso-scale self-assembly of doped semiconductor nanocrystals leading to the formation of monocrystalline nanorods showing enhanced photo-and electro-luminescence properties are reported.
5 citations