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We demonstrate a method to control the distribution of magnetic Co ions in Co-doped SnO2 nanorods by the surfactant. The nanorods with nanoflower morphology have been synthesized by surfactant-assisted hydrothermal method. The X-ray absorption fine structure spectra at Co K-edge reveal that Co ions substitute for Sn site in SnO2 lattice. The X-ray absorption fine structure spectra at O K-edge with its simulated spectra have been performed to investigate the local environment of Co ions. In the experimental spectra, the pre-edge peak continues to decline with the addition of the surfactant. It shows the same trend when the number of clustered Co ions in the simulated spectra is reduced, which indicates that the surfactant suppresses the formation of Co clusters. The effect of surfactant in mediating Co distribution arises from the strong interactions between the Co2+ ions and the CTA+ ions. In the Co K-edge experimental spectra, the weakened pre-edge peak reflects the electron transfer from the CTA+ ions to Co 3d band. Such electron transfer changes the charge state of Co ions and modifies the electrostatic interactions among dopant ions, leading to the uniform distribution of substitutional Co dopants. These results provide experimental guidance in the synthesis of the homogeneous-doped metal oxide semiconductors.

The effect of sample orientation on static recrystallization (SRX) of AZ31 magnesium alloy was investigated with electron backscattered diffraction (EBSD) technique. Two kinds of samples, one was cut along the normal direction of the sheet (0 • sample), the other along the transverse direction of the sheet (90 • sample), were given 15% uniaxial compression strain at 150 £, followed by annealing at 275 £ for different times. The results show that slip dominates the deformation process during

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The microstructure and defect evolution of Co-doped SnO2 nanostructures have been mediated by the surfactant via a hydrothermal method. The microstructure is characterized by X-ray diffraction and Raman spectra in detail. It is found that the density of structural defects considerably increases with the increase of the surfactant amount used in the preparation process. Meanwhile, the orange emission enhances dramatically. The growth process and defect evolution have been investigated by the following time-dependent experiments. Due to the existence of hollow scrolls in the growth, the mesocrystal lamellar attachment and the rolling process are proposed for the possible growth mechanism. In the synthetic process, surfactant cations, which are incorporated into the network of the self-assembled structure, strongly interact with tin hydroxyl anions. After removing the surfactants by calcination, the vacancies create in the corresponding locations, which promote the orange emission. Our finding opens a new way to control SnO2 defects and strength the optical emission.