Nano- and Micro-Scaled Zinc Oxide and Ni and Co Doped Zinc Oxide Materials

Abstract

이 연구에서는 산화아연 그리고 나노와 마이크로 크기의 물질로 이루어진 산화아연의 형상을 제어한 합성방법이 실험적으로 연구되었다. 수직면으로 이루어진 산화아연 나노로드, 1차원 zinc nickel oxide 고체용액, Ni와 Co가 첨가된 ZnO 중공구체가 간단한 용매열 과정에 의하여 성공적으로 제조되었다. 이 합성은 형판과 지지체를 사용하지 않으며, 많은 양을 값싸게 그리고 온건한 온도의 조건하에서 ZnO 나노구조물의 방향성 성장을 허락하는 용액 합성 방법을 포함한다. 다양한 형태를 가진 ZnO 혼성 물질들은 단순한 에탄올 용액 내에서 계면활성제가 직접적으로 사용되어진 용매열 과정을 통하여 성공적으로 제조되었다.

In the present study, perpendicular side-faceted zinc oxide nanorod, one-dimensional zinc nickel oxide solid solution, nickel and cobalt doped zinc oxide hollow spheres were successfully fabricated through facile one-pot template-free solvothermal methods. A surfactant-directed solvothermal synthesis approach has been successfully demonstrated on fabricating large scale of ZnO hybrid materials with diverse morphologies in a simple ethanol solution. 1. A novel route to the rational fabrication of narrow one-dimensional ZnO nanocrystals with perpendicular side facets is demonstrated in alcoholic solutions. The synthesis involves no-template or no-substrate solution method, which still allows the oriented growth of ZnO nanostructures at large-scale, low-cost, and moderate temperatures. The management consists of monitoring of the nucleation, growth, and aging processes by means of chemical and solvent control of the interfacial free energy. It enables the control of the size of nano-, meso-, and microcrystallites with various aspects from cubes to rods, wires, and belts. 2. A novel facile method has been demonstrated for large-scale synthesis of zinc oxide based one-dimensional solid solution with a series percentage of nickel dopant. The obtained Zn1-xNixO nanorods were characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and energy dispersed X-ray spectroscopy. The result shows that the obtained Zn1-xNixO nanorods are single crystalline with the Ni2+ dopants occupying tetraheral Zn2+ cation sites of wurtzite ZnO. Moreover, the Zn1-xNixO nanorods exhibit robust high-Curie-Temperature (TC) ferromagnetism at 300 K. 3. This chapter describes a template-free solvothermal treatment of precursors in methanol solvent leading to the formation of transition-metal-doped zinc oxide spheres and hollow spheres is reported. The synthesis includes hydrolysis of metal salts, spontaneous aggregation and localized Ostwald ripening in an alcohol solvent. Electron microscopy observation and X-ray diffraction analysis confirmed that the mesoscale hollow spheres with uniform in size and shape and highly crystalline structures are finely doped with transition metals such as nickel or cobalt. Magnetic hysteresis loops reveal robust coercivities at 300 K, indicating high-Tc ferromagnetism in the system. 4. A novel surfactant-directed process is successfully developed for morphology control on ZnO hybrid materials with distinctive shapes ranging from mushroom, bi-hemispheres, dumbbell, bi-layer hexagonal disks, to flower-like aggregated sheets. Replacing of the conventional oil-water system, a simple alcohol-water surfactant system is employed that provides a more environmental benign and bio-safe approach. Moreover, the remarkable ZnO hybrid materials and facile method demonstrated here not only expand the material morphologies but also provide a new approach to explore the materials for physical and chemical properties and technological applications.