Effects Of External Electric Field Polarization On Structure And Properties Of Nano-Zinc Oxide

Nano ZnO has a wide application in optoelectronic devices,luminescence,gas sensors,antibiosis,etc.Nano-ZnO powders were synthesized by by wet chemical process and electric field assisted method.The effects of external electric field on structure and gas sensing properties of nano-ZnO were investigated.Main conclusions of dissertation could be obtained as follows:?1?Nano ZnO was synthesized by microwave method and precipitation method,the Raman spectrum and gas-sensing properties of the product were characterized.The results show that the intensity of the peak at 438 cm^-1 in the Raman spectrum decreases with the extension of the polarization time,and the sensitivity of nano-ZnO in ethanol decreases,while the sensitivity in acetone gas increases;the intensity of the peak decreases first and then increases with the increase of the polarization voltage and polarization temperature.The peak intensity is inversely related to the sensitivity of nano-ZnO in acetone gas,and positively correlated with the sensitivity in ethanol gas.Ce-ZnO was prepared by coprecipitation method.The influence of external electric field polarization on Raman spectra of samples was studied.The relationship between doping ratio and the Raman spectra after polarization was analyzed.The results show that a new peak at 1056 cm^-1 appears in the anodic Raman spectrum,and the intensity of the peak increases gradually with the increase of voltage,but it can't be found in the cathodic Raman spectrum.When the sample was reversed,the peak at 1056 cm^-1disappeared,indicating that the polarization effect was reversible.ZnO and 0.1at%Ce-ZnO samples were calcined and then polarized,and the peak at 1056 cm^-1 can't be found.?2?Nano ZnO is obtained from the precursor of Zn?OH?₂ in external electric field.The effects of crystallization time,temperature and voltage on the growth of ZnO crystals were investigated.The results show that the external electric field slows the transformation of Zn?OH?₂ to ZnO.Nano ZnO grows in a cone shape,and finally forms a layered superimposed pyramid structure in electric field.Nano ZnO was synthesized by external electric field-assisted precipitation method,and the growth process was analyzed.Studies show that the external electric field enhances the electrostatic interaction between the polar surface of ZnO and the ionic species in the solution,which promotes the growth of ZnO crystals.