四氯化钛水解法制备二氧化钛纳米晶的影响因素

研究了四氯化钛水解法制备的二氧化钛纳米晶工艺中水解８温度和硫酸根离子对粉体性能的影响室温下的水解产物为无定形结构,这种粉体有着很大的比表面积,其孔为介孔尺度;添加少量的硫酸根离子使粉体的孔径在２～５ｎｍ,最可几孔径为３．８ｎｍ,提高水解温度能得到金红石与锐钛矿相的混晶,同样的水解温度下,添加少量的硫酸根离子则为纯锐钛矿相,用到金红石与锐钛矿相的混晶,同样的水解温度下,添加少量的硫酸根离子则为纯锐钛     

纳米TiO2光催化剂的电化学法制备及其表征

采用有机电解-溶胶-凝胶法制备了纳米TiO2光催化剂,通过XRD、TEM、TG-DTA、激光粒度分析法等对纳米TiO2的结构相变、表面形貌、颗粒大小等进行了表征.实验表明:当热处理温度低于350℃时,TiO2的晶相结构均为锐钛型,颗粒大小在25nm以下,样品的比表面积大于65m2*g-1;热处理温度为400℃时,TiO2的晶相结构出现锐钛型和金红石型混合相,颗粒大小在35nm以下,样品比表面积为46.43m2*g-1,实验制备的粉体样品属于纳米级水平;实验测试了各焙烧温度下粉体样品的光催化活性.     

TiO2薄膜结构的研究

研究了沉积温度和退火温度对TiO2薄膜结构的影响.当沉积温度在110～250℃时,薄膜结构为无定型,350～500℃时为锐钛型,600℃以上是金红石;当退火温度在600℃时,TiO2薄膜为锐钛型;800℃以上是金红石.氧气的加入能够影响薄膜的沉积速率,但不影响薄膜的晶体结构.     

微等离子体氧化法制备TiO2膜的光催化活性研究

用微等离子体氧化法能在钛基体上原位生长多孔TiO2膜,方法简单而且膜层与基体结合牢固.本文研究了反应时间(10、30、60、90min)对所得膜层光催化活性的影响.通过SEM和XRD分析膜层表面形貌和结构,发现随着反应时间的延长,所得膜层微孔增大而且膜层中二氧化钛含量增多.用所得膜层光催化降解罗丹明B,发现当反应时间为60min时,所得膜层具有较高的光催化活性,这归功于所得膜层比表面积增加而且膜层是由以锐钛矿型为主晶相同时含有少量金红石型二氧化钛组成.     

全国钛白行业形势不错

今年以来，锐钛型和金红石型钛白粉供需紧张，各企业产品多次提价。华东地区主要厂家的锐钛型产品吨价普遍超过万元，有的接近甚至达到1．1万元，金红石型产品吨价普遍在1．5万元以上，有的厂家吨价己达1．6万-1．7万元。     

日本东北大学开发超亲水性及吸水性光触媒材料

日本东北大学金属材料研究所等单位共同开发出比锐钛矿型氧化钛催化活性更高且不照射紫外线也具有超亲水性及吸水性的金红石型氧化钛材料（TiO2）。该材料可用于对含有害化学物质、细菌等的工业及生活排水的净化,还可用作使眼镜架用纯钛和钛合金具有抗菌性的光触媒材料,另外还可用作吸水性材料。     

TiO2 A→R相变的从头算和密度泛函计算研究

采用模型化学方法,利用从头算(Ab inito)和密度泛函(DFT)方法计算研究了氧化钛Ti5O10簇模型和V4+同晶置换Ti原子的簇模型在A→R相变中的能量变化、角度崎变方式、V4+取代位置、前线轨道变化.结果表明,V2O5晶格失去1个O原子而形成的V2O4物种具有金红石型结构,可诱导或促进TiO2的A→R相变.Ti4VO10簇中的成单α电子对体系的前线轨道产生影响;价层电子分布的这种不平衡可能是导致锐钛型结构中Ti-Ti晶格发生畸变、在加热过程中更容易向金红石型结构转变的推动力.     

几种水泥基复合材料力电耦合效应的比较

结合掺和料的形态分析,研究了碳纤维、石墨、钢纤维以及两种纳米氧化钛复合水泥基材料的力电耦合效应.研究结果表明钢纤维长径比小,密度大,和粒子状的碳黑一样,在很高掺量仍处于未渗流区,两种水泥石的力电耦合效应都不明显.碳纤维长径比大、密度小,在较小掺量即可进入渗流区,一次加载至破坏,其电阻率变化率可达20%～30%,力电耦合作用最明显.纳米氧化钛在较小掺量即可进入渗流区;金红石相纳米氧化钛水泥石不具备力电耦合效应;而复合具有半导体特性的锐钛相纳米氧化钛的水泥石具有力电耦合效应,一次加载至破坏,其电阻率变化率在7%～10%.     

纳米TiO_2晶型及粒径对PPESK超滤膜性能影响的研究

采用溶胶-凝胶法制备了不同纳米二氧化钛(TiO_2)晶型、粒径及含量的TiO_2/聚芳醚砜酮(PPESK)超滤膜,通过测定膜水通量、截留率、铸膜液黏度及膜断面的扫描电镜照片,研究纳米TiO_2晶型、粒径及含量对膜性能及结构的影响。结果表明,添加不同粒径的金红石型纳米TiO_2时,粒径较大的TiO_2使得PPESK膜水通量高于粒径较小的TiO_2;添加不同粒径的锐钛型纳米TiO_2时,粒径较小的TiO_2可以使PPESK膜具有更大的水通量和更稳定的截留率;添加不同晶型粒径相似的纳米TiO_2时,锐钛型纳米TiO_2可以更大程度的提高膜的亲水性。通过比较得出,粒径为5nm的锐钛型纳米TiO_2对于PPESK膜改性来说,效果最好,且最佳浓度为0.6%(质量分数)。     

钛白粉市场U型反转态势已成

正"十三五"开局之年的头4个月钛白粉市场迎来了"五连涨"小阳春,行业从去年的阴霾中渐渐看到了市场的曙光。然而,今年虽然五连涨,但下半年市场会是怎样呢?去年9月份国内市场在经历了三连跌后,"金九"也抑制不住下跌行情,金红石型钛白粉价格持续下跌,迫使锐钛型钛白粉被动下跌。当时硫酸法金红石、锐钛型钛白     

Enhanced photoactivity and anatase thermal stability of silica–alumina mixed oxide additives on sol–gel nanocrystalline titania

Nanocrystalline titania with silica and silica–alumina mixed oxide as additives has been prepared through a sequential approach sol–gel method starting from titanyl sulphate in aqueous medium. The mixed oxide added titania shows increased anatase phase stability and high surface area. The complete transformation of anatase to rutile in the mixed oxide added titania occurs only above 1100 °C. The silica and silica–alumina added titania precursor even after calcination at 800 °C show specific surface area of 53 m² g^− 1 and 63 m² g^− 1 respectively. Further, the mixed oxide added titania sample shows excellent photoactivity compared to the commercially available Hombikat UV 100 titania, with respect to degradation of methylene blue. The addition of mixed oxide has resulted in better properties with respect to specific surface area, increased anatase to rutile phase transformation and photocatalytic activity of titania.     

EDTA-directed synthesis of highly active porous titania with bicrystalline framework

Porous titania with bicrystalline (anatase and rutile) framework was successfully synthesized by a facile hydrothermal process using inexpensive and nontoxic organic molecules, EDTA (ethylenediamine-tetra-acetic acid) or its sodium salts as a template, which could be removed from porous titania by the extraction with sodium hydroxide aqueous solution and then easily recovered by acidification. XRD investigation suggested that the ratio of anatase to rutile could be readily tuned by employing different sodium salts of EDTA. All of as-prepared porous titania showed higher activities than the commercial photocatalyst P25 for the degradation of methyl orange (MO), because of the high surface area, bicrystalline phase composition and bimodal porous structures.     

The anatase phase of nanotopography titania plays an important role on osteoblast cell morphology and proliferation

The surface properties of biomaterials play a vital role in cell morphology and behaviors such as cell adhesion, migration, proliferation and differentiation. Three different crystal phases of titania film (rutile, anatase and amorphous titania) with similar roughness were successfully synthesized by DC reactive magnetron sputtering. The surface roughness of each film was about 8-10 nm. Primary rat osteoblasts were used to observe changes in morphology and to evaluate cell behavior at the film surface. The number of the osteoblasts on anatase film was significantly higher than rutile and amorphous films after 36 and 72 h incubation. More importantly, synthesis of alkaline phosphatase was significantly greater by osteoblasts cultured on anatase film than on rutile and amorphous films after 7 and 14 days. In addition, the cells grown on the anatase phase film had the largest spreading area; the actin filaments in cells with regular directions were well defined and fully spreaded. The results indicate that the anatase phase of titania with nanoscale topography yield the best biological effects for cell adhesion, spreading, proliferation and differentiation. There are strong therapeutic prospects for this biomaterial film for osteoblast proliferation, with possible applications for orthopedic and dental implant.     

Pulsed laser deposition of titania on rutile nanorod arrays

Oriented rutile nanorod arrays are precipitated on metallic Ti plates from a precursor derived by interactions between Ti and aqueous hydrogen peroxide. Pulsed laser deposition (PLD) is then carried out to deposit titania on the nanorod arrays, in comparison with bare Ti substrates, utilizing a high-temperature sintered rutile target in oxygen atmosphere. It is found that dense and homogeneous titania thin films are obtained on Ti substrates; while growth on the rutile nanorod arrays is epitaxial, resulting in enlarged nanorods conformally covered with titania. Titania grown on both Ti substrates and rutile nanorod arrays is either pure rutile or a mixture of anatase and rutile, with the formation of anatase favored by an increasing oxygen pressure during the PLD procedure. The surface roughness and the particle size of the dense titania films on Ti substrates increase as a result of increasing oxygen pressure and prolonged deposition time. The PLD-induced epitaxial growth of titania is inhibited by increasing substrate temperatures. The photocatalytic experiments reveal a significantly enhanced activity for the rutile nanorod arrays after a subsequent PLD treatment.     

非均匀成核法制备硅酸铝-硅灰石复合粉体材料

以硅灰石为原料,硫酸铝和硅酸钠为包覆剂,采用非均匀成核法制备一种硅酸铝-硅灰石复合粉体材料,研究搅拌速度、反应温度、反应时间、硫酸铝溶液浓度和滴加速度等工艺条件对复合粉体制备的影响。结果表明,控制机械搅拌速度为300~400 r/min,反应温度为80℃,反应时间为30 min,硫酸铝溶液浓度为0.1 mol/L,滴加速率为1~2 mL/min,可以实现硅酸铝以非均匀成核形式沉积在硅灰石表面,包覆硅酸铝后硅灰石白度提高,粒度增大,比表面积提高200%以上。     

An investigation of nanostructured rutile and anatase plates for improving the photosplitting of water

Developing new semiconductor materials for improving photocatalytic reactivity is important for solving the challenging environmental and energy problems we are facing today. This work focuses on increasing the quantum efficiency in titania photocatalysts for photocatalytic (oxidation of acetaldehyde) and photosynthetic (photosplitting of water) reactions by synthesizing pure phase rutile and anatase nanostructures with well defined morphologies and investigating their photocatalytic performance compared to a commercial titania photocatalyst (Degussa P25). Nanostructured anatase is dominated by {100} surfaces with a small amount of {101} surfaces, whereas the rutile nanoplates consist of nanorods dominated by {110} and {111} crystal surfaces. In accordance with the signals from electron spin resonance (ESR) spectra, both nanostructured anatase and rutile phases have high photocatalytic activity for photosplitting of water compared to P25 titania. The anatase phase shows a high activity for photocatalytic oxidation (PCO) of acetaldehyde whereas the rutile phase shows a lower activity. The results of these experiments basically agree with previously published works that reported that the oxidation and reduction sites on rutile particles are on the {011} and {110} faces respectively, and on {001} and {011} faces respectively for anatase particles. The results have important implications for enhancing the photocatalytic activity of titania for environmental remediation, increasing the quantum efficiency in photo-voltaic (PV) solar cells and other photo-assisted processes.     

A study of structural transition in nanocrystalline titania thin films by X-ray diffraction Rietveld method

Structural and microstructural analyses of nanocrystalline titania thin films prepared by pulsed laser deposition have been carried out. At lower oxygen partial pressures (≤10⁻⁴ mbar), rutile films were formed, whereas at 1.2 × 10⁻³ mbar of oxygen partial pressure, the thin films contained both rutile and anatase phases. At 0.04 and 0.05 mbar of oxygen partial pressure, the film was purely anatase. Addition of oxygen has also shown a profound influence on the surface morphology of the as deposited titania films. Modified Rietveld method has been used to determine crystallite size, root mean square strain and fractional coordinates of oxygen of the anatase films. The influence of crystallite size and strain on the rutile to anatase phase transition is investigated.     

Syntheses, characterization and properties of novel nanostructures consisting of Ni/titanate and Ni/titania

Ni/titanate one-dimensional nanostructures and Ni/titania nanocrystal composites were produced by a facile synthetic procedure using protonic titanate nanotubes as the precursor templates. The formation mechanisms for the nanostructures were proposed. The nickel ions first enter into the titanate matrix through three approaches, ion-exchanges reaction with the interlayered hydrogen ions, capillary forces from the microcavities, and electrostatic adsorptions due to the negatively charged outer surface of the titanate nanotubes. The following metallic nickel nucleation and growth may have occurred for these three kinds of the nickel ions reduced under hydrogen gas flow at elevated temperatures. The supports' titanate nanotubes may phase transform into the anatase titania nanocrystals and further into the mixture of anatase and rutile titania along with the increases of temperature. The Ni/titanate nanocomposites demonstrate paramagnetic behaviors and the Ni/titania nanocrystals display typical ferromagnetic behaviors. The Ni/titania sample reduced at 550 °C containing 14.5% rutile has higher photocatalytic activities than the sample reduced at 350 °C containing pure anatase, which is ascribed to a synergistic effect between anatase and rutile. The ferromagnetic characteristics of the Ni/titania products make them available as magnetically separable photocatalysts, which can be separated and recovered quickly by applying an external magnetic field.     

纳米TiO_2/SiO_2的制备与表征及其光催化活性的研究

针对二氧化钛(TiO2)纳米颗粒极易团聚、分散性差的问题,以提高TiO2分散稳定性与光催化活性为目的,采用并流中和法,以锐钛矿型纳米TiO2粉体为载体,硅酸钠(Na2SiO3)为包覆剂,使用硫酸(H2SO4)调节pH值,在纳米TiO2表面包覆致密的氧化硅(SiO2)膜。借助Fourier变换红外光谱(FTIR),X射线能量散射谱(EDS)和场发射扫描电子显微镜(FESEM)表征样品的键合情况、表面化学成分、分散性,同时借助紫外-可见分光光度计(UV-Vis Spectrophotometer)以亚甲基蓝的光催化降解反应对其光催化活性进行评价。FTIR和EDS结果表明:采用该包覆法后,SiO2以化学键合的方式沉积在纳米TiO2表面,在包覆层和纳米TiO2颗粒之间的界面上形成了Ti—O—Si键。SEM结果表明:TiO2/SiO2纳米复合粒子分散均匀,无严重团聚和大块堆积现象。光催化实验结果表明:以SiO2表面包覆后的TiO2颗粒光催化活性明显高于纯TiO2。     

Phase-pure TiO(2) nanoparticles: anatase, brookite and rutile

We report on the synthesis of phase-pure TiO(2) nanoparticles in anatase, rutile and brookite structures, using amorphous titania as a common starting material. Phase formation was achieved by hydrothermal treatment at elevated temperatures with the appropriate reactants. Anatase nanoparticles were obtained using acetic acid, while phase-pure rutile and brookite nanoparticles were obtained with hydrochloric acid at a different concentration. The nanomaterials were characterized using x-ray diffraction, UV-visible reflectance spectroscopy, dynamic light scattering, and transmission electron microscopy. We propose that anatase formation is dominated by surface energy effects, and that rutile and brookite formation follows a dissolution-precipitation mechanism, where chains of sixfold-coordinated titanium complexes arrange into different crystal structures depending on the reactant chemistry. The particle growth kinetics under hydrothermal conditions are determined by coarsening and aggregation-recrystallization processes, allowing control over the average nanoparticle size.