Papers by Author: Z.A. Talib

Abstract: This study describes the preparation of polypyrrole multiwall carbon nanotube (PPy/MWNT) composites by in situ chemical oxidative polymerization. Various ratios of functionalized MWNTs are dispersed in the water, and PPy are then synthesized via in-situ chemical oxidative polymerization on the surface of the carbon nanotubes. The morphology of the resulting complex nanotubes (MWNT-PPY) was characterized by field-emission scanning electron microscopy (FESEM). The conductivity of each composite showed a maximum in the temperature scale of 120 – 160 °C and then decreased dramatically with the increase of temperature. The resultant PPy/MWNT nanotubes enhanced electrical conductivity and thermal stability of nanocomposite compared to PPy which was strongly influenced by the feed ratio of pyrrole to MWNTs.

Abstract: The significant influences of substituting low concentration Dy at La- site for La0.667Sr0.333MnO3 perovskites compounds in structural, electrical and magnetoresistance properties have been studied. The polycrystalline samples (La1-xDyx)0.667Sr0.333MnO3 with x= 0.00, 0.02 and 0.10 were synthesized via conventional solid-state reaction in bulk. This work measured their resistivity properties with (below 1 Tesla) and without the presence of magnetic field (0 Tesla) as a function of temperature, microstructure and particle distribution and structural distortion using four point probe resistivity technique, X- ray diffractometer (XRD) and Atomic Force Microscope (AFM). The resistivity in applied magnetic field or so-called magnetoresistance ratio is defined as MR% = (Ro – RH)/RH x 100 was measured at 90K, 100K, 150K, 200K, 250K, 270K and 300K. The highest MR% values for x=0.00, 0.02 and 0.10 are 15.3%, 15.5% and 20.6% at 1 Tesla respectively. The metal- insulator transition temperature, TMIT correspond to >300K, 298K and 230K of sample with x= 0.00, 0.02 and 0.10 respectively were observed from resistivitytemperature (R-T) curve.