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In the present investigation, synthesis, characterizations and the tuning of the optical band gap (E g) of ZnO nanowires (NWs) has been successfully achieved by introducing Mg as an intentional impurity with varying concentrations Zn 1-xMg xO (x = 0, 5, 10 and 20 at. %). Although the ionic radius of Mg 2+ (0.57 Å) is close to that of Zn 2+ (0.60 Å) the crystal structure difference and large lattice mismatch between ZnO (wurtzite, 3.25 Å) and MgO (rock salt, 4.22 Å) causes phase segregation in Zn 1-xMg xO with Mg compositions between 37% < x < 62%. Optical measurements of the as grown and Mg doped ZnO NWs shows the optical bandgap tunability from ∼3.35 eV to 3.65 eV as a function of the Mg content. Rietveld refinement of XRD data for the Mg doped ZnO nanowires confirm the wurtzite structure and a continuous compaction of the lattice (in particular, the c-axis parameter) with increasing Mg content. Strong UV with weak visible emission by PL studies establishes the sensitivity of the nanostructures yield, size and band gap to the intentional impurity. This tunability of the band gap of ZnO NWs with an intentional impurity could eventually be useful for optoelectronic applications. © 2012 The Royal Society of Chemistry

Ferroelectric and piezoelectric properties of Pb1−xBax(Zr0.532Ti0.468)O3 ceramic compositions for x = 0 to 40 mole% were investigated. As Ba concentration increased, the microstructural studies revealed that grain growth was inhibited and apparent density decreased in PZT ceramics. The room temperature dielectric response (εRT) increased up to 30 mole% with low values of dielectric loss (tan δ). The ferroelectric properties (Pr, Ps and Ec) have shown a decreasing trend as Ba concentration increased from 0 to 40 mole% in the PZT system. The optimum piezoelectric charge coefficient (d33 = 473 pC N−1), piezoelectric planar coupling coefficient (kp = 0.584) and piezoelectric thickness coupling coefficient (kt = 0.408) were found in 30 mole% Ba composition, respectively.

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At the forefront of the current scientific revolution of nanoscience nanocrystals (NCs), crystalline particles grown in liquid media, stand out over other classes of inorganic nanomaterials due to the high degree of control with which their crystal structure, size, shape, and surface functionalities can be engineered in the synthesis stage and to the versatility with which they can be processed and implemented into a large spectrum of devices and processes. Doped semiconductor nanostructures can yield both high luminescence efficiencies and lifetime shortening at the same time. In the present manuscript pure and Cr-doped ZnO nanoparticles were successfully synthesized from the solution phase chemistry and investigated with respect to their structural and optical properties. The resulting powder consisting of nanocrystalline particles were characterized by X-ray diffraction (XRD), UV-Visible spectroscopy, photoluminescence spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis (EDX) techniques. A UV emission peak was observed from the exciton transition at 380 nm in the room temperature photo luminescent (PL) spectra. The blue emission band was assigned to the Zn interstitial and vacancy level transition. Even though Cr ions are known to act as an efficient non-radiative loss centre for near band gap emission (NBE), a pronounced NBE is obtained at room temperature even for a nominal Cr concentration of 8 at. %. XRD data analysis shows that the chromium dopant atoms are incorporated into the wurtzite host lattice. The grain size decreases with increasing dopant concentration. The lattice constants extracted by the Rietveld method from XRD data vary slightly with doping concentration.