Fe-doped SnO2 obtained by mechanical alloying

In this work, iron-doped SnO₂ powders were prepared by two methods: mechanical alloying and mechanochemical alloying with successive thermal treatment. The influence of different milling conditions such as ball to powder weight ratio, milling time, rotation velocity of supporting disc and the type of iron starting reactive and their Fe concentration on the structural and magnetic properties of the products were investigated. A greater incorporation of Fe in the SnO₂ structure was observed when the samples were prepared by using mechanochemical alloying and successive thermal treatment.     

稀土辅助类芬顿效应降解染料废水

以考马斯亮蓝为研究对象,应用类芬顿效应对其进行降解处理。研究了铁负载氧化镧类芬顿系统催化剂的用量,过氧化氢的投加量,pH,底物的初始浓度对处理效果的影响。实验表明,在最优的运行条件下,CBG的脱色效果可达99.48%,其中铁离子的凝絮作用也是不可忽视的重要因素,但是COD的去除率仅有34.4%。所以还需对其进行二次处理...     

Er3+∶YAlO3/Fe掺杂TiO2复合物的制备及光催化活性研究

对TiO2半导体材料进行改性,分别通过溶胶凝胶、超声波分散和溶液沸腾的方法合成了Er3+∶YAlO3/Fe掺杂TiO2复合物光催化剂,并且采用XRD和SEM进行表征,研究了各种因素在太阳光照射下降解酸性红B的催化活性,也考察了Er3+∶YAlO3的包覆量、Er3+∶YAlO3/Fe掺杂TiO2的量、太阳光照射时间、酸性红B的初始浓度和氯化钠浓度等其降解过程用UV-Vis光谱进行检测。实验结果表明,加入上转光剂之后降解率大幅度增加,改性后的光催化剂可以有效地降解染料废水。     

Mixtures of iron and anatase TiO2 by mechanical alloying

Fe-doped TiO₂ powders were obtained by mechanical alloying. The starting materials were anatase TiO₂ and metallic iron (α-Fe) or hematite (α-Fe₂O₃). The influence of different milling conditions such as: ball to powder weight ratio, milling time, rotation velocity of supporting disc, and dopant concentration on the structural and magnetic properties were investigated. All experiments were performed in atmospheric conditions. The milled powders were characterized by X-ray diffraction (XRD) using Rietveld refinement and room temperature Mössbauer spectrometry. The XRD patterns of all samples show the coexistence of both anatase and rutile phases and also the high-pressure srilankite phase. Mössbauer spectra reveal the presence of Fe²⁺ and Fe³⁺ states in Fe-doped TiO₂ as well as α-Fe or α-Fe₂O₃ in samples obtained from metallic iron or hematite, respectively. The Fe³⁺ contribution could be attributed to Fe incorporated in the TiO₂ structure and the Fe²⁺ can be probably assigned to surface ferrous ions in the TiO₂.     

Electro-codeposition synthesis and room temperature ferromagnetic anisotropy of high concentration Fe-doped ZnO nanowire arrays

Fe-doped ZnO dilute magnetic semiconductor (DMS) nanowire arrays were fabricated in anodic aluminum oxide (AAO) membranes using electro-codeposition followed by long-time anneal process. The morphology, chemical composition and crystal structure were characterized by field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (HRTEM) equipped with an energy dispersive x-ray spectrometer, and X-ray diffraction (XRD) spectroscopy. The results prove that the Fe has been successfully doped in the lattice of ZnO nanowire arrays and the estimated Fe atomic ratio is around 22%. Micro-superconducting quantum interference device (SQUID) shows that the nanowire arrays exhibit room temperature (300 K) ferromagnetic and anisotropic ferromagnetic behavior which may be a consequence of the easy magnetization direction along the wire axes and magnetostatic interaction.     

微乳液水热法制备钨酸铋光催化剂及性能研究

采用微乳液介导水热法制备Bi2WO6和Fe/Bi2WO6光催化剂,并研究水热反应温度、前驱体pH值、水相与表面活性剂的摩尔比ω值和Fe3+掺杂量对光催化剂结构、形貌和光催化活性等方面的影响.结果表明:合成的Bi2WO6为15～25 nm的纳米球状结构;当前驱体pH=1、水热温度为150℃下合成的Bi2WO6催化剂对亚甲基蓝(MB)的降解率达到93.8%;当ω=27时合成的Bi2WO6对MB光催化降解率达到了97.8%.研究发现当掺入1.03%的Fe3+的Bi2WO6比纯Bi2WO6对MB的降解率提高了2倍,达到90.2%.     

Raman spectra and ferromagnetism of nanocrystalline Fe-doped Li0.43Nb0.57O3+δ

Nanocrystalline undoped LiNbO₃ and LiNbO₃ doped with x% Fe (x=0.5, 1, 2, 3, 5) were synthesized via a combustion method. Fe-doped LiNbO₃ with a 1 mol% doping concentration exhibited a room-temperature ferromagnetism of 0.06 emu/g. There was an abrupt change in properties when the doping concentration of Fe reached 2 mol%, where the lattice contracted obviously and the saturation magnetization (M_s) increased an order of magnitude to 0.275 emu/g; M_s slightly increased to its maximum value of 1.18 emu/g when the doping concentration was further increased to 5 mol%. Raman spectra showed that the substitution of Li by Fe occurred at small doping concentrations and the substitution of Nb at the Nb site occurred at higher doping concentrations. The results suggest that Fe³⁺ replaced Nb_Li⁴⁺ first and the weaker ferromagnetism is due to the minor fraction of Nb_Li⁴⁺ in LiNbO₃. Then, Fe³⁺ substituted Li⁺, resulting in large lattice distortion and much stronger spin coupling of Fe–Nb. Finally, the excess Fe³⁺ started to replace Nb⁵⁺at the Nb sites, where the spin coupling of Fe–Nb is weaker than that at the Li site. An analysis of the experimental results suggests that the congruent Fe-doped LiNbO₃ is a promising room-temperature single-phase multiferroic material.     

Fe掺杂 SnO2纳米晶薄膜的微观结构和性能

采用反应磁控溅射法制备了Fe掺杂的SnO2薄膜.沉积衬底为(100)的单晶硅,基片温度270℃,Ar为溅射气体.使用XRD,AFM和VSM研究氧分压对薄膜晶体结构和室温磁性能的影响.实验表明,氧分压为0.12Pa时,溅射得到的化学成分为Sn0.975Fe0.025O2-δ的薄膜样品具有明显的室温铁磁性,平均饱和原子磁矩达到1.8uB/Fe.通过HRTEM和EDS分析了此样品的显微结构和成分分布,实验结果表明,薄膜由粒径3～7nm的纳米晶构成,为四方金红石SnO2相;Fe元素分布较为均匀,排除了磁性能是由第二相产生的可能;同时由于薄膜电阻率接近于绝缘体,室温磁性能不是由载流子诱导机制形成的,而与晶格内部大量缺陷的存在密切相关.     

Diffusion synthesis and electronic properties of Fe-doped ZnO

Fe-doped ZnO was successfully fabricated by thermal in-diffusion of Fe into ZnO crystals. X-ray absorption near edge structure (XANES), photoemission and cathodoluminescence (CL) spectroscopy have been combined to examine the Fe diffusion and its effects on the electronic and optical properties of the crystal. Depth-resolved CL demonstrates that Fe in-diffusion occurs to at least 4 μm depth and results in intense green luminescence, whereas the undoped crystal exhibits only the ZnO near-band-edge emission. XANES and valence-band photoemission show that Fe is incorporated as Fe^2+/3+ ions on substitutional Zn sites. The results suggest that the variation in the CL properties is due to a change in the oxygen vacancy charge state as a result of electron transfer from Fe.     

微波辅助制备掺铁纳米TiO2溶胶及其性能研究

为了进一步提高纳米二氧化钛溶胶的光催化活性,采用微波辅助胶溶的方法制备了不同铁掺杂量的纳米二氧化钛(Fe-TiO2)溶胶,并以偶氮染料活性艳红X-3B为目标物,分别考察不同铁掺杂量对纳米Fe-TiO2溶胶光催化活性的影响,研究表明原子数分数为0.05%的Fe3+掺杂量最佳;对Fe-TiO2溶胶、TiO2溶胶及P25(Degussa纳米TiO2)悬浮液的光催化活性进行对比,结果表明:TiO2溶胶与P25悬浮液光催化活性相当,而Fe-TiO2溶胶较前两者具有更高的光催化活性.采用XRD、DLS、AFM和DRS的分析方法对溶胶进行表征,结果表明:微量铁掺杂对纳米TiO2的晶型及粒径分布无显著影响;但铁掺杂可以使纳米TiO2对紫外光的吸收有较大程度的增强,同时吸收边带发生了较明显的红移.铁掺杂对于提高纳米TiO2溶胶的光催化活性和拓展其光吸收范围均具有显著的积极的作用.