ZnO is a unique material that offers about a dozen different application possibilities. In spite of the fact that the ZnO lattice is amenable to metal ion doping (3d and 4f), the physics of doping in ZnO is not completely understood. This paper presents a review of previous research works on ZnO and also highlights results of our research activities on ZnO. The review pertains to the work on Al and Mg doping for conductivity and band gap tuning in ZnO followed by a report on transition metal (TM) ion doped ZnO. This review also highlights the work on the transport and optical studies of TM ion doped ZnO, nanostructured growth (ZnO polycrystalline and thin films) by different methods and the formation of unique nano- and microstructures obtained by pulsed laser deposition and chemical methods. This is followed by results on ZnO encapsulated Fe3O4 nanoparticles that show promising trends suitable for various applications. We have also reviewed the non-linear characteristic studies of ZnO based heterostructures followed by an analysis on the work carried out on ZnO based phosphors, which include mainly the nanocrystalline ZnO encapsulated SiO2, a new class of phosphor that is suitable for white light emission.

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We report the appearance of superconductivity under hydrostatic pressure (0-2.5GPa) in Sr 0.5 RE 0.5 FBiS 2 with RE=Ce, Nd, Pr and Sm. The studied compounds, being synthesized by solid state reaction route, are crystallized in tetragonal P4/nmm space group. At ambient pressure, though the RE=Ce exhibits the onset of superconductivity below 2.7K, the Nd, Pr and Sm samples are not superconducting down to 2K. With application of hydrostatic pressure (up to 2.5GPa), superconducting transition temperature (T c ) is increased to around 10K for all the studied samples. The magneto-resistivity measurements are carried out on all the samples under 2.5GPa pressure and their upper critical fields (H c2 ) are determined. The superconductivity of these compounds appears to be quite robust against magnetic field. Summarily, the Sr 0.5 RE 0.5 FBiS 2 compounds with RE=Ce, Nd, Pr and Sm are successfully synthesized and superconductivity is induced in them under hydrostatic pressure.

We report on the structure and physical properties of polycrystalline PdTe superconductor, which is synthesized by solid state reaction route, via quartz vacuum encapsulation technique at 750 o C. The as synthesized compound is crystallized in hexagonal crystal structure with in P63/mmc space group. Both transport and magnetic measurements showed that PdTe is bulk superconductor below 4.5K. Isothermal magnetization (MH) andMagneto-transport {R(T)H} measurements provided the values of lower (H c1 ) and upper (H c2 ) critical field to be 250Oe and 1200Oe respectively at 2K, establishing that the compound is clearly a type-II superconductor. The Coherence length (ξ 0 ) and Ginzburg-Landau parameter (κ) are estimated from the experimentally determined upper and lower critical fields, which are 449Å and 1.48 respectively. Thermodynamic heat capacity measurements under different magnetic fields, i.e. C p (T)H, showed clear transition at 4.5K (T c ), which shifts gradually to lower temperatures with application of field. The values of Debye temperature (Θ D ) and electronic specific heat coefficient (γ) being obtained from C p (T) data are found to be 203K and 6.01mJ/mole-K 2 . The observed specific heat jump (ΔC/γT c ) is 1.33, thus suggesting possible weak coupling case for PdTe superconductor. PACS 74.70.-b Superconducting materials other than cuprates PACS 74.25.-q Properties of superconductors PACS 74.25.Bt Thermodynamic properties

We have investigated the structural, electronic and thermoelectric properties of GaS, GaSe and GaTe monolayers based on the first-principles approach by using density functional theory and the semi-classical Boltzmann transport equation.