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Nano-fiber structure of ZnO and Ni doped ZnO (Ni:ZnO) transparent thin films have been deposited on glass substrate at 350 C at an ambient atmosphere via spray pyrolysis technique. The structural, surface morphological and opto-electrical properties of ZnO and Ni doped ZnO thin films have been investigated. The XRD patterns show that the films are of polycrystalline in nature having preferential orientation (0 0 2) plane for ZnO changes to (1 0 1) by Ni doping in ZnO matrix. Optical study exhibits red shifting in band gap energy with Ni doping due to spd hybridization and display high absorption coefficient of the order of 10 7 m À1 . The photoluminescence (PL) spectra indicate blue emissions in all samples. Electrical measurement confirms the resistivity of the film decreases remarkably with Ni doping and electrical transport is mainly thermally activated. From Hall Effect study, it is confirmed that all the samples are n-type having carrier concentration of the order of 10 18 cm À3 . Both mobility and carrier concentrations of the films became higher than ZnO sample with the increase of Ni concentration.

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This paper presents a novel method for the preparation of temperature responsive and hollow polymer microcapsules consisting of a rigid cross-linked primary layer on the hollow core and temperature responsive shell. Temperature responsive and perfect core-shell structured magnetic polymer particles were prepared first by a two step seed emulsion polymerization process. i) Divinylbenzene (DVB) crosslinked magnetic@P(DVB) particles were obtained by the emulsion polymerization of DVB using potassium persulfate (KPS) as an initiator in the presence of an oil-in-water magnetic emulsion. ii) The magnetic@P(DVB) composite particles were then functionalized by the precipitation polymerization of N-isopropylacrylamide (NIPAm) with functional co-monomer aminoethylmethacrylate hydrochloride (AEMH) and cross-linker N,N 0 -methylenebisacrylamide (MBA). 2,2 0 -azobis(2-methylpropionamidine) dihydrochloride (V-50) was used as an initiator. Core-shell magnetic@P(DVB)@P(NIPAm-AEM) particles were then treated with concentrated HCl. The treatment with HCl dissolved the iron oxide nanoparticles from the magnetic core to form hollow P(DVB)@P(NIPAm-AEM) particles. The hollow structure of temperature responsive P(DVB)@P(NIPAm-AEM) particles prepared was confirmed by Transmission Electron Microscopy (TEM). Dynamic light scattering (DLS) results prove that the P (DVB)@P(NIPAm-AEM) hollow microcapsules are submicron in size with a narrow size distribution, cationic surface charge and most importantly, volume phase transition above its lower critical solution temperature (LCST) of P(NIPAm-AEM) shell. This volume phase transition behaviour of the P (NIPAm-AEM) shell can be utilised as an on/off switch in controlling the permeability of biomolecules or drugs into/from the hollow capsules.