The Research On Synthesis Of ZnO Whiskers By Microwave Heating Method

Znic oxide (ZnO) is a direct wide-gap compound semiconductor with the 3.37 eV bandgap and the 60 meV binding energy of the free exciton, which permits excitonic emission at room temperature and above. Because it could be realized the visible light, UV-fluorescence and laser beam, ZnO is a new-style material to prepare the short-wave LED and laser. Recently, the preparation and application of ZnO microcosmic morphology is an important research of photoelectric material.In this paper, the properties, characteristics, preparation and research present situation of ZnO low-dimensional materials have been fully summarized, especially the application and development of ZnO whiskers. The research proves that the microwave heating method is suitable to control the material morphology. The different morphologies of ZnO whiskers had been synthesized by microwave solid-phrase heating method, such as multi-needles, one-dimensional hexagonal prisms and hexagonal microtubes. The techniques of diverse morphologies ZnO whiskers have been deserved through plenty of experiments and scientific analyses considering the aspect of the component of raw materials, temperature and heating time. The multi-needle ZnO whiskers had been synthesized with the control of vapor phrase pressure under 1030℃ and 15min synthetical time; the one-dimensional hexagonal prisms had been synthesized with nano and micrometer mixed powder under 1200℃ and 30min synthetical time; the hexagonal micro tubes had been synthesized under 1350°C and 30min.According to the characteristics of microwave electric heating and the growing properties of ZnO polar crystal, the research on the growing process of ZnO whiskers with different morphologies has been done primarily. It indicates that growth mechanism is V-S, which means the ZnO powder vaporized in the region of high temperature that was filled with ZnO (g), Zn (g) and O2 (g). In the region of low temperature, the Zn (g) and O2 generated chemical reaction and decomposed at the vapor-solid interface, the different morphologies had been synthesized under different conditions, such as needles and prisms. When the temperature was high enough, the centralized location of oxygen vacancies was as the source of evaporation, and then the microtubes had been formed.The photoelectric property is on the PL spectra, which shows that the whiskers process UV property and there are some oxygen vacancies.