The electronic structure and optical properties of Zn1-x BexO alloys were studied using first principle calculation based on density functional theory （DTF）. The results indicate that the band gap of Zn1-x BexO alloys increases as Be composition increases. The major reason is that the valence band maximum （VBM） of O2p has no obvious shift while the conduction band minimum （CBM） of Zn4s shifts to higher energy as x composition increases. Calculated results of the imaginary part of the dielectric function reveal that the peak heights at 2.0 and 6.76eV decrease as x composition increases, which is attributed to the decrease of the Zn3d states after Be substitutes for Zn. Due to the increasing transition probability from VBM of O2p to CBM of Be2s in wurtzite structure BeO,the peak height at 9.9eV is enhanced and its position shifts toward higher energy.
Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduction of Co^2＋ is an irreversible process. Gd^3＋ cannot be reduced alone, but it can be inductively co-deposited with Co^2＋. Both the Gd content and microstructure of the prepared Gd-Co alloy films can be controlled by the deposited potential. The content of Gd was analyzed using an inductively coupled plasma emission spectrometer （ICPES）, and the microstructure was observed by scanning electron micrograph （SEM）. The films were crystallized by heat-treatment at 823 K for 30 s in Ar atmosphere, and then were investigated by XRD. The hysteresis loops of the Gd-Co alloy films were measured by a vibrating sample magnetometer （VSM）. The experimental results reveal that the deposited Gd-Co alloy films are amorphous, while the annealing causes the samples to change from amorphous to polycrystalline, thus enhancing their magnetocrystalline anisotropy and coercivity. Moreover, the magnetic properties of the Gd-Co alloy films depend strongly on the Gd content.
LAI HengLI JiaxinZHOU WeichaoZHUANG BinWU XiaopingHUANG Zhigao
