【作者】 丁志立； 韩杰才； 线恒泽； 张明福；

【Author】 Zhi-Li Ding Jie-Cai Han Heng-Ze Xian Ming-Fu Zhang (Center for composite materials, Harbin Institute of Technology, Harbin, 150001, China)

【机构】 哈尔滨工业大学复合材料研究所；

【摘要】 采用PVA蒸发法和有机凝胶法制备了纳米MgAl₂O₄尖晶石粉末。通过XRD、TEM等测试手段,比较两种方法制备的纳米粉末的物相结构和微观形貌等性能。对PVA蒸发法,以金属硝酸盐和聚乙烯醇（PVA）为原料,首先制得黄色蓬松的前驱体,然后经过热处理而获得所需的纳米MgAl₂O₄尖晶石粉末。考察了PVA单体与金属离子的不同摩分比对最终产物的影响,研究表明,当PVA单体/金属离子为1（摩子比）时便可得到PVA聚合物网络完全包覆的稳定前驱体,煅烧而制得纳米MgAl₂O₄粉末。对于络合物型溶胶-凝胶法,采用柠檬酸或草酸作为络合剂,通过对金属离子-络合剂平衡常数的热力学计算,绘制了金属有机络合物的稳定形成区域图,对寻找最佳制备条件（适宜的PH值和反应物浓度）以制备稳定的凝胶提供了依据。研究结果表明,凝胶可在较低的温度下和较短的时间内制备得到高纯度,高分散性的纳米MgAl₂O₄尖晶石。更多还原

【Abstract】 Nanocrystalline MgA12O4 nanometer powders have been prepared using PVA (polyvinyl alcohol) evaporation technique and aqueous organic-gel method. The PVA evaporation route, which is technically simple, most effective method, was used to obtain ultrafine, pure and reactive magnesium aluminate spinel starting from metal nitrate. The effect of the different mole ratio of PVA monomer unit and metal ion on the end product was investigated. It was found that when the mole ratio of 1 was maintained, the stable precursor encapsulated by PVA polymeric network structure was obtained, following the MgAl2O4 nanocrystallites. For the aqueous organic-gel approach, chelating agents such as citric acid or oxalic acid were used to form soluble complexes in aqueous solution. The optimum conditions (PH and concentration) for the formation of metal-organic complexes were predicted through the theoretical consideration of thermodynamic equilibrium constants of the corresponding metal salts in an aqueous solution. Nanocrystalline MgA1204 powders could be obtained through the thermal decomposition of metal-organic complexes at relatively low temperature. The crystaliinity and microstructure for powders elaborated in PVA evaporation technique and aqueous organic-gel method were examined by XRD and TEM.更多还原