The External Fields Fabrication, Structures And Properties Of ZnO Materials In Low Dimension

In this paper, it was been summarized to the crystal structure and properties of ZnO and the fabrication methods and research present situation of low-dimensional ZnO materials, Using 200nm and 20nm in average particle size ZnO powder as raw materials and no using any catalyst and by controlling synthesis temperature and time parameters, different morphologies of low-dimensional ZnO had been synthesized in 915MHz and 2450 MHz microwave solid-phrase heating method respectively, such as one-dimensional rods, multi-needles, one-dimensional hexagonal prisms and hexagonal microtubes. The techniques of different ZnO morphologies whiskers have been researched through plenty of experiments and scientific analyses. The microstructure and morphologies of ZnO crystal whiskers are characterized with XRD, SEM. The results show that line, bar, tube of ZnO whiskers have better crystallization degree, there are uniform diameter and regular morphologies especially for line and bar of ZnO crystal whiskers.Base on the characteristics of microwave heating and the growing properties of ZnO polar crystal, it was researched on the growing process of ZnO whiskers with different morphologies. It indicates that growth mechanism of ZnO whiskers is V-S growth, 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 hand been synthesized under different conditions, such as rods, needles and prisms. When the temperature is high enough, the centralized location of oxygen vacancies was as the source of evaporation, and then the microtubes had been formed.The PL spectra shows that there are UV property for the whiskers and some oxygen vacancies exist inside. Using wave guide method as well as Model Agilent N5230A vector-net analyzer, the microwave electromagnetic performances of nano-scale ZnO powder, micrometer scale ZnO powder, bar of ZnO crystal whiskers are analyzed, respectively. The results show that bar of ZnO crystal whiskers have stronger absorption at about 11GHz comparing with nano-scale ZnO and micrometer scale ZnO powder.Si(111) as substrate, ZnO ceramic as target, oxygen as environmental gas, base on the orthogonal test design rules, selecting laser energy, substrate temperature, oxygen concentration, pulse frequency, deposition time as parameters, using PLD methods optimize the deposition parameters for ZnO films growth. The ZnO films appears strong UV peak at 379nm in the PL spectra, FWHM of ZNO(002) peak in XRD is 0.275 at the deposition condition 150mJ laser energy, 500℃substrate temperature, 0.1Pa oxygen concentration, 7Hz pulse frequency, 60 min deposition time, it shows the ZnO films with high quality.The above-mentioned research proves that the microwave heating method is suitable to control the material morphology, short period of production, the convenient equipments, low cost, no pollution, saving energy, and is a green and environment friendship method with important significance and development.