【作者】 王芳；

【导师】 王金斌；

【作者基本信息】 湘潭大学 ， 材料物理与化学， 2010， 硕士

【摘要】 为了满足器件小型化和集成化的要求,近年来低维铁电纳米材料受到了人们越来越多的关注。本论文主要采用溶胶-凝胶模板法制备Bi3.15Nd0.85Ti3O12 (BNT)纳米管,对纳米管的制备工艺、微观结构和宏观物理性能进行了系统研究;另外,还初步探索了通过水热法将阳极氧化法制备的TiO2纳米管转化为BNT纳米管的工艺。具体的工作和结果概括如下:1.溶胶-凝胶模板法制备BNT纳米管及性能研究首先配制不同浓度的BNT溶胶,然后通过控制AAO模板在BNT溶胶中的浸泡时间,来控制BNT纳米管的管壁厚度。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱仪(EDS)、X射线衍射仪(XRD)、红外光谱仪(FTIR)分析BNT纳米管的结构与形貌。结果表明所制备的BNT纳米管为多晶铋层状钙钛矿结构,晶粒较小,约为30 nm左右。带有AAO模板的BNT纳米管的电学性能由铁电分析仪表征获得,分析结果表明BNT纳米管具有室温铁电性,纳米管的剩余极化(Pr)、矫顽场(Ec)均较小。光学性能由紫外-可见光谱仪(UV-VIS)和分子荧光光谱仪(FS)表征,结果表明BNT纳米管在200 nm-350 nm之间具有强烈的本征吸收,并且在蓝紫光波段具有较好的发光性能。2.水热法制备BNT纳米管及性能研究首先在含水的有机体系中采用阳极氧化法制备了规则的TiO2纳米管。然后用水热法将TiO2纳米管转化成为BNT纳米管,同时探索了水热反应条件对BNT纳米管形貌和结构的影响。采用SEM、EDS、TEM和XRD对制备的BNT纳米管的形貌和结构进行了表征,结果表明水热反应条件为200℃,12 h时,TiO2纳米管可以转化成为BNT纳米管,但是仍含有部分TiO2。当延长反应时间至48 h,96 h时,纳米管的管状结构会被破坏,生成针状晶体;当反应温度升高至250℃,反应时间为12 h时,铁电纳米管仍为针状晶体结构,而在反应时间为24 h时生成颗粒状晶体。因此,水热法制备BNT纳米管的反应条件还需进一步摸索。更多还原

【Abstract】 Because of the miniturization of electronic devices, the low dimensional ferroelectric nanomaterials are drawing great attention. In this dissertation, the main work is the preparation of Bi3.15Nd0.85Ti3O12 (BNT) nanotubes and the study of their crystalline structures and physical properties. On the other hand, a hydrothermal method is developed to fabricate BNT nanotubes, in which BNT nanotubes are obtained by transforming the TiO2 nanotubes into BNT nanotubes. The main research contents and obtained results in this thesis are summarized as follows:1. Sol-gel template synthesis and characterization of BNT nanotube arraysBNT nanotubes with differrent tube wall thicknesses were prepared by changing the immersing time of the AAO template in the different concentrations BNT sol. Scanning electron microscopy (SEM), Energy dispersive spectrometry(EDS), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) are used to characterize the microstructures and morphologies of the prepared BNT nanotubes. The results show that the obtained BNT nanotubes are polycrystalline and have a single phase of bismuth-layered perovskite structure. Polarization-electricfield (P-E) response curves of BNT nanotube embedded in AAO template were measured by a ferroelectric test system. And the hysteresis loops illustrate a room temperature ferroelectric characteristic and the values of Pr and Ec of BNT nanotubes are lower than those of thin films. The optical properties of BNT nanotubes have also been investigated by using an ultraviolet-visible (UV-VIS) spectrophotometer. The results showed that BNT nanotubes have a strong intrinsic absorption in the range of 200-350 nm and have a good blue-violet photoluminescence property.2. Synthesis and characterization of BNT nanotube arrays by hydrothermal methodFirstly, self-aligned highly ordered TiO2 nanotube arrays are fabricated by potentiostatic anodization of Ti foil using aqueous organic polar electrolytes. Then the BNT nanotube arrays are obtained by transforming TiO2 nanotube arrays into BNT nanotube arrays using a hydrothermal method. The relationships of the morphologies and structures and the reaction conditions are studied. SEM, EDS, TEM and XRD results show that the obtained BNT nanotubes still contained some TiO2 when the reaction conditions are 200 oC and 12 hours. But when the TiO2 nanotubes are reacted at the same temperature with the longer reaction time of 48 hours and 96 hours respectively, the tubular structures were destroyed and turned to an acicular crystal. Whereas, with the conditions of 250 oC, 12 hours, and 250oC, 24 hours respectively, acicular crystal and granular crystal are obtained, respectively. A further study to investigate the influence of the reaction conditions and the morphologies and structures of the BNT nanotubes is still in progress.更多还原