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Oxide coatings were prepared on Al-1050 substrates by an environment-friendly plasma electrolytic oxidation (PEO) process using an electrolytic solution of Na 2 SiO 3 (8 g/L) and NaOH (3 g/L). The effects of three different duty cycles (20%, 40%, and 60%) and frequencies (50 Hz, 200 Hz, and 800 Hz) on the structure and micro-hardness of the oxide coatings were investigated. XRD analysis revealed that the oxides were mainly composed of α-Al 2 O 3 , γ-Al 2 O 3 , and mullite. The proportion of each crystalline phase depended on various electrical parameters, such as duty cycle and frequency. SEM images indicated that the oxide coatings formed at a 60% duty cycle exhibited relatively coarser surfaces with larger pore sizes and sintering particles. However, the oxides prepared at a 20% duty cycle showed relatively smooth surfaces. The PEO treatment also resulted in a strong adhesion between the oxide coating and the substrate. The oxide coatings were found to improve the micro-hardness with the increase of duty cycle. The structural and physical properties of the oxide coatings were affected by the duty cycles.

ZnO materials with a range of different morphologies have been successfully synthesized via a simple double-solvothermal method in the presence of glycine. The morphologies of the products can be controlled from superstructures to microrods by adjusting the amount of water in the EtOH/H 2 O system. Photoluminescence (PL) studies reveal that the more amount of water was used, the stronger PL relative intensity of the green emission is, but the weaker ultraviolet emission. This might be attributed to the more defects of the products when the more water was used. The catalytic studies show that all the samples have good abilities to decrease decomposition temperature around 3006C and the decomposition temperature lowers with the increase of the relative intensity of ZnO green emission. C ontrol of the structure, size, and shape of inorganic materials has received increased attention in current materials syntheses due to the fact that they play very important roles in correlating to their magnetic, electrical, optical, and other properties [1][2][3][4] . Over the past two decades, a wide range of one-dimensional nanostructures, such as wires, rods, belts, and tubes, has been prepared [5][6][7][8] . So far, based on these 1D forms, intensive attention has been attracted to realization of 3D superstructures by patterning micro-/nano-structured building blocks with complex geometry, due to their unique properties for potential applications 9,10 . Commonly, surfactants are used as additives to assist the synthesis of materials with 3D superstructures. Therefore, developing facile, solution-based, morphology-controlled methods to fabricate novel self-assembled architectures remains challenge.Zinc oxide (ZnO), an important semiconductor with a band gap of 3.37 eV at room temperature, has attracted great interests due to its unique properties and wide applications in field effect transistors, chemical sensors, transparent conductors, and ultraviolet light emitting devices [11][12][13][14] . The properties of ZnO are strongly dependent on its morphology and aspect ratio, as well as on the size, orientation, and density of the crystal [15][16][17] . And these structural characteristics have important applications in optoelectronics and photocatalysts. ZnO with different morphologies has been produced by various synthetic methods 18. The solution based methods, such as solvothermal/hydrothermal and sol-gel processes, are attractive because the synthesis conditions used are mild and the processes are very simple. Compared to the conventional hydrothermal/solvothermal process, in which commonly only one kind of solvent is used, a double-solvothermal or a mixed-solvothermal process would have much greater influences on the structural control for various materials, because the properties of the mixed solvent can be controlled by adjusting the type and volume ratio of the solvents 19 . In biomineralization, organisms can exert great control over mineral deposition from the solution phase by using biological molecules as matrices o...

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