Phase Relations in the System TiO<Subscript>2</Subscript>-V<Subscript>2</Subscript>O<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> under Oxidizing and Reducing Conditions

The target of this work was to investigate the phase development in the catalyst system consisting of TiO₂ (Anatase) and V₂O₅ (Shcherbinaite) under several gas atmospheres. Thus a set of V₂O₅/TiO₂ specimens was prepared by ball milling and exposed to subsequent annealing in air and feed gas in the temperature range from 400 to 700 °C. The XRD-results showed that the initial phases Anatase and Shcherbinaite remain stable for all atmospheres containing oxygen. In the temperature range above 525 °C the formation of a Rutile solid solution (Rutile-ss) containing VO _x species takes place. However, under reducing conditions (lower oxygen partial pressure) the reduction of V₂O₅ to V₂O₃ was found by X-ray diffraction measurements. There is no miscibility up to 1300 °C followed by the formation of V₂TiO₅ (Berdesinskiite). SEM images underline the reduction by monitoring the change in morphology with respect to the V-containing phases. TiO₂ remains without much alteration. The two phases V₂Ti₇O₁₇ and V₂Ti₃O₉ (Schreyerite) as described in mineralogy have not been observed in these experiments. The knowledge of phase relations helps to find the appropriate processing conditions and to understand the aging phenomena of catalysts.     

钛釉乳浊机理的研究

利用XRD、SEM等测试手段研究不同组成条件下钛乳浊乳的结构和性能,探讨钛乳浊釉的乳浊相的数量、种类、分布与其组成的关系,并得到钛乳浊釉的合理的组成范围,分析乳浊机理。     

The influence of crystallinity on the resistive switching behavior of TiO2

The resistive switching characteristics of Pt/TiO₂/Al devices were investigated. Amorphous and rutile TiO₂ samples were prepared and electrically characterized. The amorphous sample was sputtered at room temperature. The rutile phase of the TiO₂ was prepared by sputtering at elevated temperatures of 500 °C. Without an electroforming process, the amorphous sample showed bipolar resistive switching in low current mode. Switchable rectifying effects have been demonstrated in this mode. After applying the electroforming process on the rutile or amorphous device both samples exhibited a bipolar switching in high current mode. Amorphous titanium oxide showed low and high current mode bipolar switching in one device.     

Fabrication and characterization of dye-sensitized solar cells from rutile nanofibers and nanorods

Rutile titania (TiO₂) nanofibers were prepared by electrospinning a polymeric sol containing a titanium precursor and Poly(vinylpyrrolidone) in acetic acid-ethanol mixture and subsequent sintering of the fibers at 800 °C. The resultant continuous, polycrystalline porous fibers contained TiO₂ grains of 15-20 nm sizes. The continuous fibers were broken down into nanorods by mechanical grinding. Morphology of the nanofibers and nanorods was characterized by scanning and transmission electron microscopies. The crystal structure and polycrystallinity of the fibers were further confirmed by X-ray diffraction analysis. Dye-sensitized solar cells (DSCs) fabricated from the nanofibers and rutile nanorods, respectively, showed superior performance with the later.     

Facile synthesis of hierarchical nanostructured rutile titania for lithium-ion battery

A facile hydrothermal method is developed to prepare rutile titania sub-microflowers consisting of nanorods with oxalic acid and TiOSO₄ as reagents. The diameter of sub-microflowers and nanorods is found to be ca. 800 and 40 nm, respectively. Also, the shape and size of building blocks in rutile titania sub-microflowers can be considerably controlled via adjusting the reaction time and reactant amounts. Rutile titania sub-microflowers composed of nanorods display higher discharge capacity and better rate cycle stability than other rutile titania nanostructures as lithium-ion battery anode material due to enhancing the Li-ion transfer rate for small size building blocks.     

Anatase–rutile transformation of TiO2 sol–gel coatings deposited on different substrates

Titanium dioxide is widely used in a lot of applications. The properties of TiO₂ strongly depend on its phase composition. The transformation temperature between phases is influenced by a lot of factors. One of them is a type of substrate under the TiO₂ film. In presented work, thin films of TiO₂ were deposited by the sol–gel method on silicon, stainless steel (304 L) and Co–Cr–Mo alloy (Vitallium). The process of anatase–rutile phase transformation was investigated by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) studies of deposited coatings. The results were compared with anatase–rutile transformations temperature of TiO₂ powders obtained by analogous sol–gel process. The temperature of anatase–rutile phase transformation changed in the range of 700–1000 °C and strongly depends on a kind of substrate. It was found that anatase–rutile transformation of TiO₂ coating proceeded at a higher temperature than rutilization of titania powders.     

Visualization of the three-dimensional microstructure of TiO2 nanotubes by electron tomography

The internal microstructure of pure rutile nanotubes has been elucidated by means of high angle annular dark field scanning transmission electron tomography. The formation and stability of pure rutile fully hollow nanotubes, after removal of carbon nanotubes used as templates is confirmed by 3D electron tomogram analysis. The size, shape and distribution of the nanocrystals which constitute the nanotube, are also characterized by tomography.     

退火温度对TiO2薄膜结构和表面形貌的影响

研究了退火温度对中频交流反应磁控溅射技术制备的TiO2 薄膜结构和表面形貌的影响。利用X射线衍射仪和原子力显微镜 ,检测了TiO2 薄膜的晶体结构和表面形貌。实验结果显示 :沉积态TiO2 薄膜为非晶态 ;低温 (70 0℃以下 )退火后 ,TiO2 薄膜出现锐钛矿相 ,晶粒长大不明显 ;高温退火 (90 0℃以上 )后 ,薄膜转变为金红石相 ,晶粒由柱状转变为棱状 ,并迅速长大至微米量级     

红安群变质地层中几种地质体的成因浅析

本文对红安群变质地层中常见的三种地质体的成因,作出了分析解释。它们是:围岩片理平行于变基性岩体与围岩的接触面分布;绿帘石英岩脉和赋存于榴辉岩体中的金红石矿。笔者认为这些地质体的形成与退变质作用、构造作用、变质分异作用等地质作用有关。     

枣阳大阜山原生金红石矿脱泥试验研究

对枣阳大阜山原生金红石矿进行了选矿试验研究,为有效减少矿泥和脉石对浮选影响,分别采用了单一摇床重选、重磁联合、沉降和反浮选工艺进行脱泥抛尾,脱泥之后再进行金红石浮选。试验结果表明,在浮选前进行脱泥作业能够显著提高浮选指标,反浮选脱泥抛尾工艺效果更好,一次性抛弃尾矿产率为10.85%,金红石损失率为7.08%,反浮选脱泥后再进行正浮选,采用C5-9羟肟酸作为捕收剂,经过一次粗选,精矿品位达21.12%,回收率达75.08%。