磁控溅射TiO2薄膜的相结构转变温度

利用射频磁控溅射制备了TiO2致密薄膜,并通过退火处理实现TiO2的相转变,采用扫描电镜,X射线衍射等手段对薄膜相结构进行表征并做了详细的分析,结果表明,退火后TiO2薄膜结构致密,表面呈现出大小均匀的纳米晶粒。400 ℃退火时,TiO2薄膜为单一的锐钛矿相,500～600 ℃退火时为锐钛矿和金红石混合相,700 ℃以上退火时则完全转变为金红石相。     

阳极氧化制备TiO_2纳米管阵列的可控相转变及表征

采用电化学阳极氧化法制备TiO2纳米管阵列,分别在O2、N2、5%H2+95%N2(体积分数)和NH3气氛中于400~650℃退火处理,初步实现TiO2纳米管中锐钛矿向金红石相转变的可控制备。采用FESEM、XRD、Raman对退火处理后TiO2纳米管的表面形貌、结构以及相转变等进行表征。结果表明:随着退火温度的升高,在O2气氛退火时,源于Ti基体的吞噬效应(Feeding effect)是导致TiO2相转变的主要原因;在N2和(5%H2+95%N2)气氛退火后,氧空位加速了锐钛矿向金红石相的转变;而在NH3气氛中退火后,N掺杂则有效抑制了锐钛矿向金红石相的转变。在此基础上,对其相转变机理进行了初步探讨,为进一步制备具有可控相含量及微观点缺陷的TiO2半导体和高性能器件提供了有益思路。     

TiO2光催化纳米薄膜的晶化处理

TiO2光催化纳米薄膜在400℃～80℃温内恒温退火1h-2h，以消除膜内非晶，提高薄膜光催化活性。热处理前后试样的检测结果表明：退火使TiO2薄膜内非晶晶化，晶粒长大，光响应电流增大。随退火温度的升高，TiO2薄膜出现由非晶斗锐钛矿斗金红石的转变。其中，600℃退火1h的TiO2薄膜为锐钛矿加金红石的混晶结构，光电流密度最大Iuv=41．2A／m^2，光催化活性最好。     

纳米多孔TiO2膜的晶化处理及其热稳定性研究

通过恒压阳极氧化法在HF酸和CrO3的混合电解液中，在纯钛TAl和钛合金TC4表面分别制备了纳米多孔无定型TiO2膜。研究了TAl和TC4表面无定型TiO2膜在空气中热处理的组织转变过程。TAl试样表面的纳米多孔TiO2膜在250℃左右出现锐钛矿相，480℃左右出现金红石相，在600℃左右锐钛矿相向金红石相的转变基本完成，孔结构在600℃左右基本消失；TC4试样表面的纳米多孔TiO2膜在310℃左右出现锐钛矿相，600℃左右出现金红石相，在680℃左右锐钛相向金红石相的转变基本完成，孔结构在700℃左右基本消失。TC4试样表面的氧化膜所含合金元素Al和V，对上述结晶转变温度和孔结构存在的最高温度的差别存在重要影响。     

全球钛原料现状与市场展望

发展正交结构的高压相β-TiO2可通过高能球磨锐钛矿TiO2而得到。高能机械球磨减小了颗粒尺寸，球磨40h后，发现样品存在2nm～4nm的类点状颗粒和10nm～35nm的类花瓣状颗粒。高能球磨改变了锐钛矿TiO2晶粒的晶格常数，该晶格畸变现象可能与晶界区行为相关。红外吸收峰随球磨而先“蓝移”后“红移”，该“蓝移”与“红移”与晶格常数a的变化紧密相关。另外发现随着球磨时间增长，TiO2的光催化效果变差。     

电弧功率对液料等离子喷涂TiO2纳米涂层结构的影响

采用液料等离子喷涂法，在不同电弧功率条件下，用含有0．2w(钛酸丁酯)的乙醇溶液为喷涂材料，制备了TiO2涂层。用扫描电镜、透射电镜和X射线衍射仪分析了涂层的显微组织结构与晶型结构，计算了涂层中的锐钛矿相相对含量与晶粒尺寸。结果表明，液料等离子喷涂TiO2涂层为纳米颗粒堆积形成的纳米结构涂层，涂层由锐钛矿相和金红石相两相构成。涂层中锐钛矿相含量可超过70％，并随着电弧功率的增大而减小。涂层中TiO2晶粒的平均尺寸为20～60nm且随电弧功率的增大而增大。     

退火温度对TiO2薄膜结构和光学性能的影响

为制备光学性能良好的TiO2薄膜.采用离子束溅射(IBS)的方法,改变退火温度,在Si基底上制备氧化钛(TiO2)薄膜.利用XRD、XPS、SEM测试薄膜的成分、结晶形式和表面形貌,椭圆偏振光谱仪分析薄膜折射率和消光系数.试验结果发现:随退火温度的增加,薄膜由锐钛矿相变为金红石相,400℃薄膜结晶为锐钛矿相TiO2,1 100℃退火后,薄膜结晶为金红石相TiO2;退火温度升高使薄膜折射率和消光系数随之升高.由此可得, 800℃退火时,TiO2薄膜具有最佳光学性能.     

热喷涂法制备的La3+掺杂纳米TiO2粉末的表征

采用等离子热喷涂法以钛酸四丁酯为主要原料制备出稀土离子掺杂的纳米TiO2光催化剂.通过XRD,XPS,TEM,UV-Vis等检测手段对样品进行表征,同时检测了其光催化性能,并分析了掺杂对TiO2的影响机理.结果表明,所制备的La3 掺杂纳米TiO2是锐钛矿相和金红石相混晶结构,粒径分布在10～50nm之间;La3 掺杂能够促进锐钛矿向金红石的转变,同时抑制TiO2晶粒的长大;La3 掺杂使TiO2紫外-可见吸收光谱发生红移;适量La3 掺杂能显著提高TiO2的光催化活性,最佳掺杂浓度为0.5%(与Ti原子摩尔比),甲基橙降解率在90min内可达到82.4%.比纯TiO2高出13.2%.     

退火温度及TiO_2结构对羟基磷灰石的沉积诱导作用

采用阳极氧化法在钛金属表面制备TiO2薄膜,将表面改性的钛金属在过饱和钙化溶液中浸泡,在其表面沉积羟基磷灰石,研究了退火处理温度对TiO2薄膜晶型转变的影响以及TiO2的晶型结构对羟基磷灰石的诱导沉积作用。研究表明,300℃退火处理,TiO2薄膜为板钛矿相,500℃退火处理转变为锐钛矿相,高于500℃退火处理,锐钛矿相开始向金红石相转变。其中锐钛矿相的TiO2对羟基磷灰石的沉积具有最好诱导作用,沉积物分布均匀,板钛矿相对羟基磷灰石的诱导作用最差,所形成的沉积层是由片状的羟基磷灰石围成的多孔结构。     

湖南大学研发纳米二氧化钛改性氟碳涂料

湖南大学余刚、胡波年和杨景花等人日前研究成功一种纳米二氧化钛改性氟碳涂料及其制备工艺与应用，该涂料是将锐钛矿型纳米TiO2和金红石型纳米TiO2混合物添加到现有氟碳涂料中，添加比例为：锐钛矿型纳米TiO2和金红石型纳米TiO2混合物，氟碳涂料的质量比为1～4：100；所述锐钛矿型纳米TiO2和金红石型纳米TiO2混合物中，锐钛矿型纳米TiO2和金红石型纳米TiO2二者质量配比为4：1。本发明还包括所述改性氟碳涂料的制备工艺及用于涂敷铝合金板材的前处理工艺。使用本发明之氟碳涂料涂装后的铝合金型材和板材具有良好的白清洁性能，耐沾污和耐洗刷性能，良好的耐候性、耐化学腐蚀性，防水防潮，质量轻、防震、隔声、隔热、色泽均匀、不开裂、不变形、不剥落、不褪色等特点。     

Phase transformation of nanocrystalline anatase powders during high energy planetary ball milling

1　INTRODUCTIONTitaniumdioxideisknowntoexistinthreecrys tallineformsofrutile ,anataseandbrookiteinnature .Rutileisthermodynamicallystablewhileanataseandbrookitecantransformirreversiblyandexothermicallytorutileoverarangeoftemperatures[1] .Inaddition ,therearetwohigh pressurephases ,srilankitewithorthorhombicstructureandTiO2 Ⅲ .Underhighpressure ,anataseandrutilecantransformtosri lankite[2 4 ] .Thesrilankitephasecantransformbacktorutileunderappropriateconditions[5] .Overthepastfew years …     

高能球磨制备Al3Ti/Al块体纳米晶复合材料

通过对Al Ti系和Al TiO2 系进行高能球磨和压制烧结制备了固态原位反应生成的纳米晶块体Al3Ti/Al复合材料。研究表明 :Al Ti合金系高能球磨后 ,各组元晶粒得到细化 ,并且Ti在Al中发生了强制超饱和固溶 ,烧结时原位反应形成纳米晶Al3Ti/Al复合材料 ;而Al TiO2 反应体系高能球磨仅发生组分晶粒细化 ,烧结时TiO2 部分还原并和Al原位反应生成纳米晶 (Ti2 O3 Al3Ti) /Al复合材料。     

Phase Evolution and Thermal Analysis of Nanocrystalline AlCrCuFeNiZn High Entropy Alloy Produced by Mechanical Alloying

A multi-component nanocrystalline AlCrCuFeNiZn high entropy alloy with 12 nm crystallite size was successfully synthesized using high energy ball milling. The progress of solid solution formation during milling was analyzed using XRD. A major portion of the HEA is observed to be BCC in crystal structure after 30 h of milling. Thermal analysis showed that HEA powders exhibited exponential oxidation characteristics. Thermal analysis showed that low activation energy was sufficient to start recrystallization because of high energy stored in the milled powders. The crystallite size after consolidation is in nanocrystalline range due to the sluggish diffusion of atoms and nanotwinning. After consolidation, the crystallite size is around 79 nm. Samples sintered at 850 °C for 2 h exhibited high hardness values of 700 ± 15 HV_1.0, major volume fraction of the phases are having FCC crystal structure along with a minor phase having BCC crystal structure. Due to positive enthalpy mixing of Cu with other elements, decomposition of BCC to new FCC phases occurs.     

退火工艺对二氧化钛薄膜光催化性能的影响

利用磁控溅射法制备得到二氧化钛薄膜,将薄膜在高温管式炉中分别进行退火,利用XRD、AFM和紫外-可见光谱仪研究了不同温度下退火前后薄膜的晶相结构、光学性能和光催化性能。结果表明,随着退火温度的升高二氧化钛的晶相由锐钛矿向金红石转变,600℃时为两相共存,表面颗粒大小也会有相应变化,锐钛矿相表现出了更好的光催化性能。     

初始压力对气相爆轰合成纳米二氧化钛纳米颗粒的影响

介绍了利用氢氧混合气体、四氯化钛组成的多元气相系统,爆轰制备纳米二氧化钛粉体的方法。利用XRD分析证明产物为二氧化钛混晶(金红石相和锐钛矿相),晶粒尺度为纳米级。通过XRD、TEM分析可以得出,粒子形状不规则,粒度为20~100nm。研究发现,随着初始压力的增大,金红石相含量增加,纳米颗粒的平均粒度增大,其原因是反应放热的增加和湍流的加强。最后初步探讨了气相爆轰合成纳米二氧化钛粉末的生成机制。     

Properties of TiO2 film prepared from titanium tetrachloride

The properties of TiO₂ film prepared by titanium tetrachloride were investigated with respect to annealing temperatures in terms of phase change, crystallite size, and band gap energy. The TiO₂ film dried at room temperature exhibited an amorphous phase, while films calcined above 281 and at 990°C displayed anatase TiO₂ and a mixture of anatase and rutile, respectively. The TiO₂ film was transformed to an anatase phase through three stages during the annealing processes: (1) removal of water, (2) decomposition of a peroxo group, and (3) amorphous-anatase phase transformation. It was also found that the bandgap energy of TiO₂ film was changed with increasing annealing temperature. This is attributed to the quantum size effect in the range of 475–675°C and to the formation of rutile phase having lower band gap energy than anatase in the range of 675–990°C.     

盐酸浸出机械活化和碳热还原钛铁矿制备纳米二氧化钛(英文)

采用一个新工艺来处理天然钛铁矿并制备高品位的人造金红石纳米颗粒。该工艺主要包括球磨、碳热还原和盐酸浸出步骤。天然钛铁矿通过球磨处理后,颗粒尺寸会大幅度减小;后续的碳热还原会导致高钛渣的形成。在盐酸浸出工序中,重点考察了酸浸时间、温度和酸的浓度对浸出过程的影响。通过优化工艺条件,最后所得到的产品为纯度超过98.0%、颗粒尺寸为10～200nm的TiO2纳米颗粒。     

Application of statistical methodology for the evaluation of mechanically activated phase transformation in nanocrystalline TiO2

Response surface methodology was employed to study the effect of three factors, namely as milling time, milling speed and ball to powder weight ratio, on the mechanical activation of polymorphic phase transformation in nanocrystalline TiO₂ powder and identify the probable interactions between these factors. The response was the rutile percentage after annealing the samples. Based on the statistical analysis, ball to powder weight ratio was found as the most effective factor and just one statistically significant interaction was found between milling speed and ball to powder ratio. It was also shown that increasing the milling time has no significant effect on the phase transformation since the required activation energy for the phase transformation is unattainable under these conditions. The rutile percentage was calculated from X-ray diffraction patterns of the samples via Rietveld refinement method. Raman spectroscopy was employed to verify the phase composition analysis based on X-ray diffraction results.     

机械球磨氧化银制备银纳米晶的热力学分析(英文)

对高能球磨氧化银制备银纳米晶的可行性进行热力学分析。根据结构缺陷如非晶化、位错和表面能,计算机械活化样品的摩尔吉布斯自由能函数。根据摩尔吉布斯自由能函数,计算得到机械球磨21h还原氧化银的平衡温度约为304K。在304K下,氧化银不稳定,在球磨过程中会还原成银。     

Addition of catalysts to magnesium hydride by means of cold rolling

In this paper we compare the techniques of cold rolling and ball milling as a mean to synthesized nanocomposites MgH₂ + 2 at.%X where X = Co, Cr, Cu, Fe, Mn, Nb, Ni, Ti, V. High energy ball milling was performed under argon for 30 min while cold rolling was done in air with a number of roll limited to five. Particle and crystallite sizes are smaller in the ball milled compounds than in the cold rolled ones. The hydrogen sorption kinetics of the ball milled compounds was also faster than the cold rolled samples but not by a wide margin. Because cold rolling was done in air, this limited the number of rolls that could be performed. It is expected that rolling under protective atmosphere will enable a higher number of rolls and better sorption kinetics.