Dissertation
Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Preparation and Properties of ZAO Target

Author WangHanBin
Tutor ShaoZhongBao
School Northeastern University
Course Physical and chemical
Keywords nanometer-sized ZnO ZAO compound powder ZAO target a method of direct precipitation mechanically ball milling method at high temperature
CLC TB383.1
Type Master's thesis
Year 2009
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ZAO is an n-type semiconductor formed by doping a small quantity of Al2O3 in ZnO. Recently, the ZAO gets more and more attention for its Properties capability which is as good as ITO (Sn2O3:In). In this paper, nano ZnO and Al2O3 are synthesized by a method of direct precipitation, and ZAO nano composition powder is prepared by a mechanically ball milling method at high temperature. In addition, the influence of preparation conditions on the properties of the ZAO target is discussed.The ZnO nano powder is prepared by the method of direct precipitation through taking ZnSO4·7H2O and NH4HCO3 as raw materials. The influence of Zn2+ concentration and sintering temperature on its properties is discussed. In the same way, the Al2O3 nano powder is prepared by the method of direct precipitation through taking AlCl3·6H2O and NH4HCO3 as raw materials. Finally, the properties of the powder are characterized by means of thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM). The influence of doping amount of Al2O3 and sintering temperature on the electric resistivity and consistency of the ZAO target.The results show that the mean particle size of the ZnO nano powder prepared under the optimal experimental conditions is about 47 nm. The optimal experimental conditions are 7.5 of pH value,80℃of reaction temperature,1.6 mol/L of the concentration of NH4HCO3 solution,0.5 mol/L of the concentration of Zn2+ and 700℃of the sintering temperature. In addition, the mean particle size of the Al2O3 nano powder prepared at 1100℃is 50 nm. The powder has the advantages of uniform particle size distribution, ball-shaped particles and high purity. It is demonstrated that high-performance nano powder can be prepared at lower temperature through the mechanically ball milling method at high temperature by contrasting the mean particle size, particle size distribution and surface appearance of the ZAO compound powder prepared respectively by the method of direct precipitation and the high-energy ball milling method. The optimal preparation conditions are 3wt% of doping amount of Al2O3 and 1300℃of the sintering temperature. The electric resistivity of the target prepared at the conditions is 8.2×10-2Ω·cm, and its relative density is 90.8%.

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