Study On Preparation Technology For Nano-Zno By Two-Step Method

Nano-ZnO,as a new kind of functional material,has special properties and application in the field of magnetism, sensitivity, antibiosis and antipoisoning, ultraviolet ray shield, etc which the common ZnO has not. Now there are many preparation methods for nano-ZnO, as concerning preparation technology, there are one-step method and two-step method. Considering industrialization, now there are many studies on two-step method, precipitation and thermal decomposition. Among two-step method, different precursors with different properties can be made by different raw materials. The kinds, properties, thermal decomposition surrounding of precursors influence the properties of nano-ZnO greatly. And it determines the investment and the cost of product.In this paper, two-step method is chosen to synthesize nano-ZnO indirectly using ZnCl₂, (NH₄)₂CO₃ and ZnCl₂, (NH₄)₂C₂O₄ as raw materials respectively. Two precursors Zn₅(CO₃)₂(OH)₆ and ZnC₂O₄ · 2H₂O are made. Resort to XRD, TEM, DTA etc, the precursors and nano-ZnO are tested in order to determine what it is and its size and pattern.The result of the test shows that the factors which affect the preparation of nano-ZnO by two-step method can be considered in two aspects. Firstly, the main factors dominating the precipitation reaction are temperature, time, reactant concentration and its ratio, they can take effect on the properties of precursors directly, and the properties is important to the thermal decomposition reaction. Secondly, the factors that affect the thermal decomposition reaction are reaction temperature and time, and they affect the synthesis of nano-ZnO directly. The results show that the effect of thermal decomposition reaction in the second step is more significant than that of precipitation reaction in the first step.Using (NH₄)₂CO₃ and ZnCl₂ as raw materials, the best precipitation reaction conditions are: time 30min, temperature 60℃, concentration of Zn²⁺ 0.5mol/l, ratio of...