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We report the urchin-like ZnO nanostructures composed of self-assembled cone-shaped ZnO nanorods grown on the Zn-deposited Cu substrate fabricated by electrodeposition-hydrothermal method. In the FESEM images, the cone-shaped ZnO nanorods radiate from the center of the nanostructure forming a spherical urchin-like shape with a diameter of 5 μm–10 μm, the average diameter and the length of the cone-shaped ZnO nanorods can be identified as 0.1 μm–1 μm and 3 μm–5 μm, respectively. The SAED of the diffraction ring suggests that this ZnO nanorod was polycrystalline with the wurtzite hexagonal phase. The measured optical band gap Eg values are 3.12 eV, 2.98 eV, 3.04 eV and 3.10 eV respectively with the increasing pH values. In the as-prepared condition, the photoluminescence (PL) spectra of the urchin-like ZnO nanostructures are composed of a violet emission band at about 393 nm and two blue emission bands at about 446 nm and 463 nm at room temperature. With an increase in the pH value of hydrothermal solution, the intensity of PL spectra increases, while the forbidden gaps of four samples become narrower. Finally, a possible growth mechanism of the urchin-like ZnO nanostructures has been discussed. [ABSTRACT FROM AUTHOR]

Hierarchical flower-like ZnO nanostructures and Mg-doped ZnO flower-like hierarchical nanostructures composed of porous nanosheets were synthesized via a one-step hydrothermal method. In this method, Zn(NO 3 ) 2 ·6H 2 O was used as a precursor and Mg(NO 3 ) 2 ·6H 2 O was the dopant. FESEM, EDS, XRD, UV–vis absorption spectra and PL spectra were used to characterize the samples. It demonstrates that small portions of Mg are successfully incorporated into the lattice of the ZnO nanostructures. The incorporation of Mg into ZnO is supported by broadening and higher Bragg angle shift in XRD pattern and EDS analysis. Cell Parameters of hierarchical flower-like Mg-doped ZnO nanostructures are obtained from Rietveld analysis. The decrease of c- axis indicates that substitution by Mg 2+ is the dominant doping form in the hierarchical ZnO nanostructures. PL spectra show that the effective Mg doping suppresses the near band gap emission and the green emission. The band edge emission shifts to the blue with increasing amount of Mg doping, reflecting the change in the excitons energy seen in the absorption spectra. The defect band is believed to be due to deep traps and becomes dominant at high levels of doping. All the results show that the molar ratio of Mg and Zn determines the structure, surface morphology and optical properties of the samples significantly. [ABSTRACT FROM AUTHOR]

Abstract: The 773K isothermal section of the phase diagram of the Ho–Co–Fe ternary system was investigated by using X-ray diffraction technique, metallographic analysis and scanning electron microscopy with energy dispersive analysis. The isothermal section of the ternary system consists of 6 three-phase regions, 16 two-phase regions and 11 single-phase regions. Three pairs of corresponding compounds of Ho–Co and Ho–Fe systems, i.e., Ho2Co17 and Ho2Fe17, HoCo3 and HoFe3, HoCo2 and HoFe2, form a continuous series of solid solution. At 773K the compound Ho6Fe23−x Co x was found to have a wide homogeneity range from 0 to 29at.% Co. The maximum solid solubilities of Fe in Co, Ho2Co7, Ho12Co7 and Ho3Co were determined to be about 10, 9, 2 and 5at.% Fe, respectively. The maximum solid solubility of Co in Fe is found to be 78at.% Co. [ABSTRACT FROM AUTHOR]

Abstract: The isothermal section of the phase diagram of the Y–Fe–Cr ternary system at 773K was investigated by X-ray powder diffraction (XRD), optical microscopy, differential thermal analysis (DTA), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The isothermal section consists of 8 single-phase regions, 14 two-phase regions and 7 three-phase regions. The maximum solid solubilities of Cr in Fe, Y2Fe17, Y6Fe23 and YFe2 are 13, 18, 6 and 6at.% Cr, respectively. The maximum solid solubility of Fe in Cr is about 15at.% Fe. It was found that there is some homogeneity range in the ternary compound of YFe12−x Cr x with x =2.1–3.4 at 773K. [Copyright &y& Elsevier]