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Diffusion of water confined in sodium bentonite clay is studied using the quasi-elastic neutron scattering (QENS) technique. Hydration of bentonite clay is characterized by several methods including X-ray diffraction and thermogravimetric measurements. X-ray diffraction shows that the clay is having a well-defined crystalline structure with an interlayer spacing of 13 Å. The QENS experiment has been carried out on hydrated as well as dehydrated clay at room temperature. Significant quasi-elastic broadening was observed in case of hydrated bentonite clay whereas dehydrated clay did not show any broadening over the instrument resolution. Analysis of QENS data reveals that diffusion of water occurs through jump diffusion. Both Jump diffusion models having random and Gaussian distribution in jump length are used to describe the observed dynamics. Obtained diffusion coefficient is found to be lower than that of bulk water.

Nickel oxide nanopowder was synthesized by sol gel method using nickel nitrate as the starting material. Nickel oxide nanoparticles with a grain size of 15-90 nm have been studied by; small angle neutron scattering; scanning electron microscopy; and vibrating sample magnetometry. A combination of Ferro and paramagnetic behaviour of the particles after calcination at 800 °C is observed while for powder calcined at 400 °C, soft magnetic character with saturation is seen. The system of nanoparticles ofNiO embedded in a silica matrix is also studied for the structural change. Weak magnetic ordering is observed in this case with the likely-hood of particles being evenly distributed in the silica.

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