Kolen'ko Yury V, Kovnir Kirill A, Gavrilov Anton I, Garshev Alexei V, Frantti Johannes, Lebedev Oleg I, Churagulov Bulat R, Van Tendeloo Gustaaf, Yoshimura Masahiro
Department of Materials Science, Moscow State University, Moscow 119992, Russia.
J Phys Chem B. 2006 Mar 9;110(9):4030-8. doi: 10.1021/jp055687u.
The formation process of titania based nanorods during hydrothermal synthesis starting from an amorphous TiO2.nH2O gel has been investigated. Sodium tri-titanate (Na2Ti3O7) particles with a rodlike morphology were prepared by a simple hydrothermal process in the presence of a concentrated NaOH aqueous solution. The ion exchange reaction of the synthesized Na2Ti3O7 nanorods with HCl under ultrasonic treatment promotes a complete sodium substitution and the formation of H2Ti3O7 nanorods. Low-temperature annealing of the as-produced nanorods of Na2Ti3O7 and H2Ti3O7 leads to a loss of the layered crystal structure and the formation of nanorods of condensed framework phases-sodium hexa-titanate (Na2Ti6O13) and metastable TiO2-B phases, respectively. These transformations proceed without a significant change in particle morphology. The nanostructures were investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), and Raman spectroscopy. The structural defects of the synthesized nanorods were investigated by high-resolution electron microscopy. The presence of planar defects can be attributed to the exfoliation of the zigzag ribbon layers into two-dimensional titanates as well as to the condensation of the layers of TiO6 octahedra into three-dimensional frameworks.
研究了从无定形TiO₂·nH₂O凝胶开始水热合成过程中二氧化钛基纳米棒的形成过程。在浓氢氧化钠水溶液存在下，通过简单的水热过程制备了具有棒状形态的三钛酸钠（Na₂Ti₃O₇）颗粒。合成的Na₂Ti₃O₇纳米棒在超声处理下与HCl发生离子交换反应，促进了钠的完全取代并形成了H₂Ti₃O₇纳米棒。对所制备的Na₂Ti₃O₇和H₂Ti₃O₇纳米棒进行低温退火，分别导致层状晶体结构的丧失以及形成凝聚骨架相的纳米棒——六钛酸钠（Na₂Ti₆O₁₃）和亚稳TiO₂-B相。这些转变过程中颗粒形态没有明显变化。通过扫描电子显微镜（SEM）、粉末X射线衍射（XRD）、布鲁诺尔-埃米特-泰勒（BET）法、热重分析（TGA）和拉曼光谱对纳米结构进行了研究。通过高分辨率电子显微镜研究了合成纳米棒的结构缺陷。平面缺陷的存在可归因于锯齿形带状层剥落为二维钛酸盐，以及TiO₆八面体层凝聚为三维骨架。
