不同碳酸盐沉淀剂热分解法制备纳米氧化锌

以硝酸锌为锌源,分别以碳酸钠和碳酸氢铵为沉淀剂,采用热分解碱式碳酸锌工艺制备纳米氧化锌。通过热重分析、晶型测试、平均粒径测试、微观形貌观察等系列对比,分析了以两种碳酸盐为沉淀剂制备氧化锌的过程,建立了生长动力学方程,对比了微观形貌和分散状态。实验结果表明,以碳酸氢铵为沉淀剂制备的前驱体在煅烧温度为200℃后直接生成纳米氧化锌,而以碳酸钠为沉淀剂制备的前驱体在煅烧温度为200~250℃时先生成碳酸锌然后在300℃时完全转变为氧化锌;两种沉淀剂制备纳米氧化锌的生长过程符合不同指数方程生长关系,以碳酸钠为沉淀剂制备纳米氧化锌的生长满足方程y=2.775 04e0.004 76x,而以碳酸氢铵为沉淀剂制备纳米氧化锌的生长满足方程y=5.152 96e0.002 85x,对比来看以碳酸氢铵为沉淀剂制备纳米氧化锌在相同温度下得到的晶粒尺寸要小;从粒度分布和透射电镜观察分析,在相同温度下也是以碳酸氢铵为沉淀剂制备的纳米氧化锌的粒径较小。

Preparation of nano-sized zinc oxide by thermal decomposition with different carbonate precipitates

Nano-sized zinc oxide was prepared by thermal decomposition process of basic zinc carbonate,with zinc nitrate as zinc source,and sodium carbonate and ammonium hydrogen carbonate as precipitants.The formation process,growth kinetics equa-tion,micromorphology and dispersion state of zinc oxide samples by two kinds of carbonates were analyzed by thermogravime-tric analysis,crystal form test,average particle aize test and microscopic morphology.It was found that zinc oxide was obtained directly at 200 ℃ using ammonium hydrogen carbonate as precipitant; while using sodium carbonate as the precipitant,the precursor changed into zinc carbonate at 200~250 ℃,and then completely transformed into zinc oxide above 300 ℃.The growth process of nano-sized zinc oxide prepared by two precipitants was in accordance with the growth relationship of differ-ent exponential equations.The growth of nano-sized zinc oxide prepared using sodium carbonate as precipitant was satisfied the equation of y=2.775 04e^{0.004 76x},while the growth of nano-sized zinc oxide prepared using ammonium hydrogen carbonate as precipitant was satisfied the equation of y=5.152 96e^{0.002 85x}.Smaller grain size of zinc oxide was prepared by using ammonium bicarbonate as the precipitant at the same temperature through the growth kinetics equations.Smaller particle size of zinc ox- ide was prepared by using ammonium bicarbonate as precipitant through particle size distribution and electron microscopy.