【作者】 刘志伟；

【导师】 印万忠；

【作者基本信息】 东北大学 ， 矿物加工工程， 2005， 硕士

【摘要】 纳米氧化锌是一种新型功能材料,在磁、光、电、敏感、抗菌消毒、紫外线屏蔽等方面具有普通氧化锌产品所不具备的特殊性能和用途。目前纳米氧化锌的制备方法很多,就制备工艺过程而言,有一步法和二步法。从工业化角度出发,目前的研究以沉淀-热分解二步法居多。在二步法中,原料与反应条件的不同,可以制得不同种类和性质的前驱物,前驱物的种类、性质、热分解环境与条件等因素对纳米氧化锌的性质均会产生很大影响,并决定着整个工艺过程的投资与产品成本。 本文采用二步法,分别以碳酸铵、氯化锌和草酸铵、氯化锌为原料,制备出前驱物碱式碳酸锌和二水合草酸锌,进而制备出纳米氧化锌。借助于XRD、TEM、DTA等测试手段,对前驱物和纳米氧化锌进行检测,确定其物相组成、粒度和形貎,并最终确定了两种前驱物制备纳米氧化锌的适宜工艺流程和相应的工艺参数。 试验结果表明:二步法制备纳米氧化锌的影响因素应分两步考虑,第一步沉淀反应的主要影响因素有反应时间、反应温度、锌离子浓度和反应物浓度比,它们直接影响着前驱物的性能,而前驱物的性能对第二步热分解反应又会产生一定的影响;第二步热分解反应的主要影响因素有反应温度和反应时间,并且第二步热分解反应的影响大于第一步沉淀反应。 以碳酸铵和氯化锌为原料时,最佳沉淀反应条件为:反应时间30min,反应温度60℃,锌离子浓度0.5mol/l,碳酸根和锌离子浓度比1.0/1.0;最佳热分解条件为:反应温度370℃,反应时间2h。上述条件下,可制得粒径分布均匀、平均粒径为23nm的纳米氧化锌。以草酸铵和氯化锌为原料时,最佳沉淀反应条件为:反应时间20min,反应温度50℃,锌离子浓度0.5mol/l;最佳热分解条件为:热分解温度500℃,热分解时间2h。上述条件下,可制得粒径分布均匀、平均粒径为28nm的纳米氧化锌粉体。 本文结合水溶液溶解度理论、溶液的热力学及动力学理论、晶核形成与生长理论,对碱式碳酸锌和二水合草酸锌的形成机理进行了研究,并初步探讨了前驱物的热分解过程及其机理。更多还原

【Abstract】 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更多还原