不同反应参数下纤蛇纹石纳米管的水热合成研究

HYDROTHERMAL SYNTHESIS OF CHRYSOTILE NANOTUBES AT DIFFERENT REACTION-PARAMATERS

以活性MgO和纳米SiO2为原料,在仿地质作用的碱性水热环境下控制不同反应参数合成了多个系列的纤蛇纹石样品。利用XRD和IR分析系统地研究了不同反应参数对纤蛇纹石特征的影响。结果表明,活性MgO和纳米SiO2在水热环境中很容易转变成纤蛇纹石相,但形成完善纳米管结构须严格控制水热反应条件;pH值、反应温度和反应时间的提高均有利于水热合成结晶度及管状结构更加完善的纤蛇纹石,最佳水热反应条件为pH=13.8,200℃,反应60h,此条件下无其它杂质产物生成,合成温度较前人采用的300℃有所降低。利用SEM和AFM对最佳反应条件下合成的纤蛇纹石纳米管的形貌进行了观察,发现其为短柱状,准直性较高,表面光洁无杂质,直径均一,约50nm,长度多为400～500nm。

：By controlling the reaction-parameters and in the alkaline hydrothermal-environment which was a simulation of geological action, some series of chrysotile samples were synthesized from activated MgO and nanophase SiO2. Then, X-ray diffraction analysis and infra-red sepectrometric analysis were conducted to systematically study the influence of different reaction-parameters on the synthesis of chrysotile tubes. The results showed that： activated MgO and nanophase SiO2 are transformed readily into chrysotile phase in the hydrothermal-environment, but the chrysotile nanotubes from under strict hydrothermal conditions ; The crystallinity of chrysotile nanotubes increases and the tubu- lar structure grows better as pH, temperature and reaction time increase, and the best hydrothermal conditions are pH = 13.8, temperature is 200 ℃ and reaction time is 60 hours, under which no other mineral is generated. Furthermore, this synthesis temperature is lower than that taken by predecessors （300 ℃ ）. Using transmission electron mi- croseopy and atomic force microscopy to observe the shape of chrysotile nanotubes synthesized under the best hydrothermal eonditions, we have found that they are shortcolumnar in shape and of high collimation. Their surface is clean and their diameters are homogeneous （about 50 nm）. Most of the chrysotile nanotubes are 400 -500 nm in length.