A spiral carbon nanofiber of 30 to 40 nm diam and 20 mm average lengths has been synthesized by catalyst chemical vapor deposition method using Ni or Fe-Ni alloy as catalyst. The purpose of synthesis of carbon nano fibers was to use it for hydrogen adsorption. Catalysts used affected the morphology of carbon nano material (CNM) where as purification and ball milling of CNMs affected the hydrogen adsorption. The hydrogen adsorption is found to be 0.296 wt% and 0.334 wt% at hydrogen pressure of 11 Kg/cm 2 with as grown and purified CNMs with nitric acid respectively. After the ball milling of CNMs, their hydrogen storage capacity decreased to 0.222 wt%.

Al substituted M type Ca hexaferrite with composition CaAl x Fe 12-x O 19 (x ¼ 0, 0.2, 0.4, 0.6, 0.8) were synthesized by sol gel auto combustion method. The prepared samples were characterized by XRD, SEM, FTIR and VSM. X ray diffraction study shows that the with increasing aluminum ion concentration lattice parameter a decreases from 5.87 A to 5.83 A while the lattice parameter c decreases from 22.15 Å to 22.00 Å are well within the range of M type of hexaferrite. The crystallite size of the particles decreases from 74.36nm to 62.12nm are suitable for magnetic recording. Morphology of the particles from SEM images was hexagonal platelet. The absorption band between 580 and 440cm À1 in FTIR confirm the formation of hexaferrite. The magnetic properties of the samples changes with Al ion substitution make the material suitable for low density longitudinal and perpendicular magnetic recording.

Phase diagram and spin-glass phenomena in electron-doped La1−xHfxMnO3 (0.05≤x≤0.3) manganite oxides J. Appl. Phys. 110, 113914 (2011) Rectifying characteristic of perovskite oxide La1.89Ce0.11CuO4/Ba0.5Sr0.5TiO3/La0.67Sr0.33MnO3 heterostructures J. Appl. Phys. 110, 103716 (2011) Strain modulated magnetization and colossal resistivity of epitaxial La2/3Ca1/3MnO3 film on BaTiO3 substrate Appl. Phys. Lett. 99, 092103 (2011) Magnetoresistance in epitaxial thin films of La0.85Ag0.15MnO3 produced by polymer assisted deposition Appl. Phys. Lett. 99, 083113 (2011) Additional information on J. Appl. Phys. Despite numerous attempts to explain the phenomenon of transport and magnetoresistance in manganites based on Jahn-Teller phonon coupling and double exchange mechanisms, satisfactory results could not be reached. The small polaron transport mechanism, based on the valence exchange arising from Madelung energy, is shown to account for the resistivity and magnetoresistance of the doped manganite La 2/3 Ca 1/3 MnO 3 in the ferromagnetic range. The transport equation for the correlated polaron based on the Holstein Hamiltonian shows the well known transition from the low temperature band to the localized polaron hopping conductivity at high temperature in agreement with experiment. The present attempt is to demonstrate that the complexity of the problem that involves the interplay between the spin and charge order on one hand and itinerant and localized behavior on the other for a simple ferromagnetic metal system of manganites is best described by the correlated small polaron model leaving the more complicated systems for future studies.

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