High-pressure polymorph of TiO2-II from the Xiuyan crater of China

Abundant TiO2-II, a high-pressure polymorph of titanium dioxide, was found in the gneiss fragments of impact-produced breccias from the Xiuyan crater. Rutile in the gneiss was severely fragmented and fine-grained clasts less than 2 ~tm in size had been transformed to TiO2-II. Irregular thin layered TiO2-II is also observed in coarse-grained ruffle fragments, where the TiO2-II layers distributes along fractures and cracks in rutile, About 30 percent of rutile in the gneiss had been transformed to TiO2-II. Fine grains of TiO2-II display light bluish grey to light yellow brown in plane-polarized reflected light. Crystallographic investigation shows that TiO2-II has an orthorhombic structure with space group Pbcn. The cell parameters are a=4.543（1）/~, b=5.491（9）/~ and c=4.895（2） ,~. Its empirical formula calculated on the basis of two oxygen atoms can be written as （Tio.985Feo.oosNbo.oor- Si0.003Zr0.0Ol）l.0O302, or simply formula TiO2. According to the shock effects of quartz and feldspars, the peak shock pressure and post-shock temperature in the TiO2-II-bearing gneiss are estimated to be between 35 and 43 GPa and 300-900~C, respectively. The finding of TiO2-II in the shock-metamorphosed gneiss provides another mineral physics evidence for shock origin of the Xiuyan crater.     

水处理中的高级氧化技术

高级氧化技术在有机废水治理方面因为具有反应速度快、处理完全、无公害、适用范围广等优点逐渐引起了各国的重视,并相继开展了研究与开发工作,但是其具体的反应机理仍然是众多学者争论的焦点。本文对目前水处理领域中的高级氧化技术进行了系统的分析和总结。     

卤素离子在Ti/nano TiO2-Pt电极上的电化学行为

采用电化学合成法和电沉积法制备高活性纳米TiO2-Pt修饰电极(Ti/nanoTiO2-Pt电极),用循环伏安法和线性扫描法研究了卤素离子在Ti/nanoTiO2-Pt电极上的电化学行为,以及离子液体([EMI]BF4)中卤素离子的电化学行为,并与Ti/nanoTiO2和石墨电极进行比较.结果表明,Ti/nanoTiO2-Pt电极对卤素离子有显著的电催化活性,Epa=0.94V,ΔEp=0.098V,Ipa/Ipc=1,为准可逆电极过程.     

Pt掺杂锐钛矿型TiO2电子结构和光学性质第一性原理研究

为了研究Pt掺杂对锐钛矿型TiO2电子结构和光学性质的影响,本文采用基于密度泛函理论的平面波超软赝势方法,对未掺杂和Pt掺杂锐钛矿型TiO2的电子结构和光学性质做第一性原理计算。得到了掺杂前后的品格结构常数、结合能电子态密度分布、能带结构、介电函数虚部、光吸收系数等性质,定性地分析了掺杂前后能带结构和光学性质的变化。研究结果表明,Pt掺杂锐钛矿型TiO2带隙中能产生新的能带,而且能带位置明显下移,掺杂后不但能使TiO2的吸收带产生红移,而且在可见光区具有较大的吸收系数,表现出较高的光催化活性,理论与实验基本吻合。     

光催化技术及其在造纸废水中的应用

TiO2光催化技术是近年来日益受重视的污染治理新技术.本文就光催化技术的基本原理及提高光催化效率的途径做了一般的阐述,并介绍了其在造纸废水处理应用方面的研究进展、存在的问题及发展前景.     

漂珠负载TiO_2膜的制备及其光催化降解特性

以钛酸丁酯为先驱物,经过溶胶凝胶过程在漂珠转换（FB）表面负载成膜,得到具有光催化特性的样品（TiO2/FB）.经扫描电镜（SEM）、X射线粉末衍射（XRD）以及傅立叶转换红外光谱分析（FTIR）等多方表征,TiO2在漂珠表面的成膜厚度约为2μm,由粒径尺寸约为100 nm的TiO2颗粒组成;经650℃处理,无定形的TiO2转变为金红石型;TiO2薄膜与漂珠表面之间通过Ti-O-Si键连接.研究了溶胶凝胶条件以及漂珠表面的羟基化处理,对TiO2成膜形貌的影响以及TiO2/FB对亚甲基蓝的光催化降解特性.结果表明,以紫外灯为光源,经180 min照射,TiO2/FB对亚甲基蓝的光降解率达到92%.     

阳极氧化法制备TiO2纳米管阵列及其表征

采用阳极氧化法在钛金属表面制备出致密有序的TiO2纳米管膜层.利用FESEM、XRD方法研究了不同阳极氧化时间、电解液组成以及退火对TiO2纳米管形貌的影响.讨论了TiO2纳米管的形成机制.     

涂覆纳米TiO_2薄膜的自洁玻璃研究

采用溶胶-凝胶法,并用浸渍提拉技术制备了涂覆纳米TiO2薄膜的自洁玻璃.通过热分析讨论了凝胶的转变过程.对比了自沽玻璃的亲水性.研究了该样品的光催化性能.研究表明,干凝胶的最佳热处理制度为升温速度为12℃/h,450℃时保温1h;镀膜6次的试样具有最好的光催化能力;样品在日光照射下也具有良好的亲水性和一定的自洁性能,但是,在可见光(不含紫外线)的照射下,没有体现出明显的亲水性和自洁性能.     

Recent progress in studies on the nano-sized particle layer in rock shear planes

Since the 1990s, an ultramicro-particle texture in nano- or micron-sized scale has been continually found in shear planes of various rocks, and recently further progress was obtained by studying the generic mechanisms on both physics and mechanics. In this article, the characteristics of the nano-sized particle layer in rock shear planes (including the widespread distribution, layering texture, non-linear genetic mechanism, and multiple functions) on an ultra micro-scale were briefly introduced and more information was proposed by analyzing examples from home and broad.We found that there is a paragenetic relationship between the development of shear frictional-viscous and the formation of nano-sized particles and that in the shear movement, partitioning, segregating, and layering in rocks are initiated by the sliding motion of the nano-sized particle layer. Moreover, the plastic rheology of rocks is essentially the movement of ultra micro-sized particle (nano-size and micro-size), and the nano-sized particle layer in rock shear planes are characterized by some particular physical and chemical effects.     

La3+和Ni2+掺杂二氧化钛纳米粉体的制备与光催化性能

采用溶胶 凝胶法分别制备了未掺杂、La³⁺和Ni²⁺单掺与共掺的TiO₂粉末,通过XRD、SEM、UV-visible吸收等对样品的晶型、微观形貌、光吸收和对亚甲基蓝的光降解特征进行了考察。结果表明,La³⁺和Ni²⁺的掺杂抑制了TiO₂的相变和晶粒的增长,纯TiO₂的粒径主要分布为20～30nm,掺杂La³⁺和Ni²⁺后样品的晶粒尺寸在9～20nm之间。掺杂后各样品在紫外和可见光区的吸收能力均有不同程度地增强。与未掺杂TiO₂的吸收带边相比,La³⁺掺杂TiO₂的吸收带边蓝移,Ni²⁺掺杂和共掺TiO₂的吸收带边分别红移了约40和35nm。La³⁺单掺和La³⁺-Ni²⁺共掺促进了光生电子-空穴对的分离,从而提高了光催化降解亚甲基蓝的活性。