水热法合成碲化铋粉体及其热稳定特性

Hydrothermal Synthesis and Thermal Stability of Bi_2Te_3 Powders

通过改变实验条件,在130～200℃、NaOH溶液浓度为2～8 mol/L的较宽水热条件下合成出单相Bi2Te3粉体。利用X射线衍射(XRD),透射电镜(TEM),高分辨透射电镜(HRTEM),能谱色散仪(EDAX),热分析系统(TG-DTA)对产物的物相组成,形貌特征和晶体结构,热稳定性进行了研究。结果表明当不添加表面活性剂时,在一定反应温度下,NaOH溶液浓度不仅是合成纯Bi2Te3粉体的重要因素,而且影响所得Bi2Te3粉体的晶体形貌和晶粒尺寸。当NaOH溶液浓度较低、反应温度较高时,以原子结合方式生成Bi2Te3,反之,以离子结合方式生成Bi2Te3。一般形成机理的提出对今后采用水热法或溶剂热法合成碲化物有一定帮助,而热稳定性的研究对实验结果提出新的要求。

Single phase Bi2Te3 was obtained under loose hydrothermal conditions with reaction temperature range of 130-200 ℃ and NaOH concentration range of 2-8 mol/L.X-ray diffraction（XRD）,transmission electron microscope（TEM）,high-resolution TEM（HRTEM） and thermal analysis system（TG-DTA） were employed to study the phase composition,morphology and crystal structure,thermal stability of the powders.The result indicated that NaOH concentration plays an important role not only in determining the formation of pure Bi2Te3,but also in the morphology and grain size of Bi2Te3 nanostructures under a certain reaction temperature.Bi2Te3 was generated by atomic combination with the low NaOH concentration at high temperature and by ion combination on the contrary.The two reaction mechanism of atomic and ion combination was proposed,which contribute to the synthesis of tellurides via hydrothermal and solvothermal process.Thermal stability was also discussed,which raise demands of the experimental results.