摘要
采用水热合成方法制备出外径约8nm,壁厚为1nm的纳米管,以TEM、XRD和TG等分析手段对不同工艺条件下获得的产物进行了表征,对它们的热稳定性进行了测试。结果表明,纳米管是在NaOH水热处理过程中形成的,而不是在清洗过程中形成的。其形成机理可能是纳米氧化钛颗粒在强碱作用下形成的Na2TiO3片状物经过卷曲而成短纳米管,通过溶解-吸收机理,逐渐长成长纳米管。但清洗溶液的pH值对生成的纳米管的成分和结构有影响,通过控制清洗产物溶液的pH值和热处理温度,可以获得组成分别为Na2TiO3、H2TiO3和TiO2的纳米管,且纳米管具有较好得热稳定性,经400℃热处理后,能保持其纳米管形貌,600℃时,纳米管间有烧结的迹象,至800℃时纳米管完全变为颗粒状。
Nanotubular titanates, with an external diameter of 8nm and a wall thickness of about 1nm, were prepared by hydrothermal processing.The thermal stability of the products was tested,and their morphology and phase structures were analysed by means of transmission electronic microscopy (TEM)、X-ray diffraction (XRD) and thermal analysis (TG) respectively. The experimental results indicated that the formation of nanotubular products was due to hydrothermal treatment, rather than washing processes. However, pH values of washing solutions determined the composition of products. Na_2TiO_3, H_2TiO_3 and TiO_2 nanotubes were synthesised by controlling the conditions of washing process and heat-treatment. The nanotubes may be formed from nanosheets through curling in the primary stage, and grew longer by dissulation-reprecipitation processing with the increase of reaction time. The nanotubes remained in their shape at 400℃, fused together at 600℃, and completely lost their nanotubular shape to give aggregated anatase nano-particles at 800℃.
出处
《材料开发与应用》
CAS
2004年第5期9-12,25,共5页
Development and Application of Materials
关键词
二氧化钛纳米管
水热法
形成机理
热稳定性
Titanate nanotubes
Hydrothermal method
Mechanism of formation
Thermal stability
