铁氧化物薄膜气敏材料的制备及性能研究评述

本文综合介绍近年来在铁氧化物薄膜气敏材料制备方法、性能方面的研究新进展 ,探讨了各种方法的特点。提出了今后铁氧化物气敏传感器的研究及改进方向     

国内铁氧化物的研究现状

在大量阅读国内外有关铁氧化物文献的基础上,综述了国内铁氧化物制备的不同方法,包括沉淀法制备铁氧化物、水解法制备铁氧化物、特殊方法制备铁氧化物、纺锤形铁氧化物的制备、掺杂离子制备去铁氧化物、FeOOH的热处理、FeOOH制备的动力学研究等.指出国内以氧化Fe(OH)2制备FeOOH,然后转化为Fe2O3的方法对于制备均匀单分散的胶体粒子有先天不足,其制备过程复杂,容易受制备条件影响.     

铁氧化物薄膜气敏材料的制备及性能研究评述

本文综合介绍近年来在铁氧化物薄膜所敏材料制备方法、性能方面的研究新进展，探讨了各种方法的特点。提出了今后铁氧化物气敏传感器的研究及改进方向。     

明胶-铁氧化物纳米复合微粒的制备和性能

用微乳液法制备了明胶包裹的复合氧化铁纳米量级超细微粒。XRD,TEM,SEM和IR测试表明:微粒为明胶包裹球形超细微粒。微球的粒径为1.5 μm~3 μm,而微粒的粒径为20 nm。每个复合微球中约有35个~90个氧化铁粒子。该复合微粒的比饱和磁化强度σ_s=62Am2/kg,矫顽力Hc=187 Oe,剩磁r=10.18Am2/kg,具有硬磁体的性质。将其用于制备磁流变液,在低的磁场强度下有较大的MR效应,沉降稳定性优于用羰基铁粉制成的磁流变液。     

协同制备氧化物SrFeCo0.5Oy的研究

采用柠檬酸溶胶凝胶合成法协同微波加热烧结制备了混合导体氧化物SrFeCo0.5Oy。利用差热分析（DTA）、X-射线衍射(XRD)、电子透射电镜(TEM)与电子扫描电镜(SEM)对合成与烧结样品进行了分析与表征，当羧酸根，硝酸根的比值(α)为0．64时，在550℃下焙烧干凝胶即可得到单相钙钛矿结构的Sr-Fe-Co0.5Oy混合氧化物，而且合成的氧化物SrFeCo0.5Oy颗粒细小、分布均匀。微波协同烧结制备的SrFeCoO.5Oy，氧化物的样品相对密度达到96％。与常规烧结样品相比较，协同烧结制备温度低，时间短；所得样品的绝对主相为钙钛矿型SrFe1-xCoxO3-δ相。     

碱土金属复合氧化物的光催化性能研究

用柠檬酸法制备了碱土金属钙钛矿和二氧化钛复合氧化物,X射线衍射和电子显微镜等技术分析了样品的晶相组成、含量以及粒径等.以紫外杀菌灯为光源,甲基橙水溶液为被降解物,对所制备的系列复合氧化物进行了光催化活性评价.实验结果表明:在相同条件下,最佳配比的复合氧化物的光催化活性顺序为:钙复合氧化物＞钡复合氧化物＞锶复合氧化物＞镁复合氧化物.以n(Ca):n(Ti)=3:7配比制得的复合氧化物具有最好的光催化活性,分析结果表明,在500℃下焙烧4h后,其复合物粒径约10.2nm,光照3h,对甲基橙的降解率达90%.     

铁氧化物纳米晶自组装空心微球的制备、表征及其应用

铁氧化物纳米材料和纳米结构空心微球分别代表了材料研究中组分和结构的研究热点. 而由铁氧化物纳米晶自组装形成的空心微球的研究则是二者相结合, 具有重要的科学意义和良好的应用前景. 虽然已发展了多种方法制备各种单质及化合物的空心微球, 但铁氧化物纳米晶自组装空心微球的制备方法报道较少. 本文简要介绍了近几年发展起来的多种铁氧化物纳米晶自组装空心微球的一些制备方法, 利用上述方法, 制备出了多种不同组成单元、不同尺寸、不同空心程度的铁氧化物纳米晶自组装空心微球, 对所制备的铁氧化物纳米晶自组装空心微球进行了表征, 并初步介绍了所制备的铁氧化物纳米晶自组装空心微球在药物缓释和环境领域中的应用.     

不锈钢热处理后表面氧化物的清洗研究

通过正交试验优选了一种用混酸溶液(HF HNO3)清洗热处理后不锈钢表面氧化物的酸洗工艺,并在最优结果的条件下通过正交试验确定了缓蚀剂的最佳配比,最后对最优酸洗工艺进行了试验验证.试验结果表明,用HF HNO3的混酸能彻底清洗掉不锈钢表面的氧化物.在酸洗介质中添加缓蚀剂后能很好地抑制酸对不锈钢基体的腐蚀.     

钠离子电池铁氧化物/碳基复合材料研究进展

探索高性能、低成本、环境友好型电极材料一直是电化学储能领域的研究重点,其中,铁氧化物(FeO_x:Fe₃O₄、α-Fe₂O₃、γ-Fe₂O₃)作为钠离子电池负极材料具有较大的应用潜力而受到广泛关注。然而,FeO_x的电子和离子传导性较差,限制了循环稳定性和倍率性能,将其与碳基材料(石墨烯、石墨/无定型碳、多孔炭、碳纳米管和碳纳米纤维等)进行复合能够显著改善电化学性能。本文详细介绍了FeO_x/碳基复合材料作为钠离子电池负极材料的研究现状。分析了导致FeO_x负极材料首次库伦效率低、循环稳定性和倍率性能差等问题的原因,以及各复合改性结构的优势,对今后FeO_x/碳基复合材料作为钠离子电池负极材料的研究方向进行了展望。     

Adherence rates to ferric citrate as compared to active control in patients with end stage kidney disease on dialysis

Introduction: Oral phosphate binders are the main stay of treatment of hyperphosphatemia. Adherence rates to ferric citrate, a recently approved phosphate binder, are unknown. Methods: We conducted a post‐hoc analysis to evaluate whether adherence rates were different for ferric citrate vs. active control in 412 subjects with end stage kidney disease (ESKD) who were randomized to ferric citrate vs. active control (sevelamer carbonate and/or calcium acetate). Adherence was defined as percent of actual number of pills taken to total number of pills prescribed. Findings: There were no significant differences in baseline characteristics including gender, race/ethnicity, and age between the ferric citrate and active control groups. Baseline phosphorus, calcium, and parathyroid hormone levels were similar. Mean (SD) adherence was 81.4% (17.4) and 81.7% (15.9) in the ferric citrate and active control groups, respectively (P = 0.88). Adherence remained similar between both groups after adjusting for gender, race/ethnicity, age, cardiovascular disease (CVD), and diabetic nephropathy (mean [95% CI]: 81.4% [78.2, 84.6] and 81.5% [77.7, 85.2] for ferric citrate and active control, respectively). Gender, race/ethnicity, age, and diagnosis of diabetic nephropathy did not influence adherence to the prescribed phosphate binder. Subjects with CVD had lower adherence rates to phosphate binder; this was significant only in the active control group. Discussion: Adherence rates to the phosphate binder, ferric citrate, were similar to adherence rates to active control. Similar adherence rates to ferric citrate are notable since tolerance to active control was an entry criteria and the study was open label. Gender, race/ethnicity, nor age influenced adherence.     

膜法纯化液相沉淀法合成的纳米Fe2O3水合物

采用超滤膜分离技术纯化由液相沉淀法合成的纳米氧化铁水合物,考察超滤膜材质及截留分子量(MWCO)、膜分离过程操作参数对透过通量大小及稳定性的影响;并研究膜污染机制及相应的清洗方案.结果表明,纯化效果好、效率高,且污染膜易于清洗,可重复使用,膜法纯化不失为一有效的纯化新途径.     

Development of pure and doped gamma ferric oxide

Optimum conditions and experimental details for the formation of γ-Fe₂O₃ from goethite have been worked out. In another method, a cheap complexing medium of starch was employed for precipitating acicular ferrous oxalate, which on decomposition in nitrogen and subsequent oxidation yielded acicular γ-Fe₂O₃. On the basis of thermal decomposition in dry and moist nitrogen,dta, xrd, gc and thermodynamic arguments, the mechanism of decomposition was elucidated. New materials obtained by doping γ-Fe₂O₃ with 1–16 atomic percent magnesiu, cobalt, nickel and copper, were synthesised and characterized.     

Novel approach to zinc removal from circum-neutral mine waters using pelletised recovered hydrous ferric oxide

Data are presented which evaluate the performance of a pilot-scale treatment system using pelletised hydrous ferric oxide (HFO; a waste stream from coal mine water treatment) as a high surface area sorbent for removing zinc (Zn) from a metal mine water discharge in the North Pennines Orefield, UK. Over a 10-month period the system removed Zn at mean area- and volume-adjusted removal rates of 3.7 and 8.1gm(-3)day(-1), respectively, with a mean treatment efficiency of 32% at a low mean residence time of 49min. There were seasonal effects in Zn removal owing to establishment and dieback of algae in the treatment tank. This led to increased Zn uptake in early summer months followed by slight Zn release upon algae senescence. In addition to these biosorptive processes, the principal sinks for Zn appear to be (1) sorption onto the HFO surface, and (2) precipitation with calcite-dominated secondary minerals. The latter were formed as a product of dissolution of portlandite in the cement binder and calcium recarbonation. Further optimisation of the HFO pelletisation process holds the possibility for providing a low-cost, low footprint treatment option for metal rich mine waters, in addition to a valuable after-use for recovered HFO from coal mine water treatment facilities.     

Facile synthesis of magnetic iron oxide nanoparticles and their characterization

Magnetic iron oxide nanoparticles are synthesized by suitable modification of the standard synthetic procedure without use of inert atmosphere and at room temperature. The facile synthesis procedure can be easily scaled up and is of important from industrial point of view for the commercial large scale production of magnetic iron oxide nanoparticles. The synthesized nanoparticles were characterized by thermal, dynamic light scattering, scanning electron microscopy and transmission electron microscopy analyses.     

添加剂对水热法制备超细氧化铁的影响

以硫铁矿烧渣酸浸液为原料，采用水热法制备超细氧化铁。添加剂对水热产物的物相影响较小，但对水热产物形貌影响较大。当水热反应温度为190℃、反应时间为30min、总铁浓度为3mol／L、n（Fe^2＋）/n（Fe^3＋）取0．145时，加入添加剂CTAB、NaH2PO4、CO（NH2）2水热反应所得产物为椭球形粒子；加入PVP、OP所得水热产物为球形氧化铁粒子，但其粒径差异较大。酸浸液中n（Fe^2＋）／n（Fe^3＋）物质量之比对水热产物物相和形貌有重要影响。当n（Fe^2＋）/n（Fe^3＋）为0时，水热产物为大小均匀的球形超细Fe2O3粒子，其粒径约为0.11μm；当n（Fe^2＋）／n（Fe^3＋）为0．145时，其水热产物颗粒增大、粒径各异，物相为Fe2O3、Fe3O4；当n（Fe^2＋）/n（Fe^3＋）为0.842时，从放大3万倍SEM照片，难以观测其形貌与粒径大小，其物相为Fe3O4。     

A biotechnological perspective on the application of iron oxide nanoparticles

In recent decades,magnetic iron nanoparticles (NPs) have attracted much attention due to properties such as superparamagnetism,high surface area,large surface-to-volume ratio,and easy separation under external magnetic fields.Therefore,magnetic iron oxides have potential for use in numerous applications,including magnetic resonance imaging contrast enhancement,tissue repair,immunoassay,detoxification of biological fluids,drug delivery,hyperthermia,and cell separation.This review provides an updated and integrated focus on the fabrication and characterization of suitable magnetic iron NPs for biotechnological applications.The possible perspective and some challenges in the further development of these NPs are also discussed.     

Isothermal thermal diffusivity of iron oxide

Using the flash technique, the thermal diffusivity of iron oxide has been measured as a function of time at temperatures ranging from 623 to 753 K to study the isothermal decomposition of wustite to magnetite and iron. The results are briefly discussed in terms of transformation kinetics and it is shown that the data are consistent with the growth of a fixed number of nuclei, all of which are present at the start of transformation.     

应用于海水烟气脱硫的陶瓷负载氧化铁催化剂的制备及表征

以FeSO4为原料,分别采用浸渍沉淀(Ⅰ)和溶胶-凝胶法(Ⅱ)制备了轻质陶瓷负载氧化铁催化剂。研究了制备方法和焙烧温度对负载后氧化铁层的结构、形貌和团聚状况的影响。Ⅱ法制备的催化剂有较高SO2脱除活性,使用SEM-EDS,XRD,XPS和H2-程序升温脱附(H2-TPR)等表征结果可以看出,Ⅱ法制备的催化剂有13.28%(质量分数)的氧化铁负载于陶瓷表面,负载后Fe的价态为+3,还原峰温度分别为380和600℃,依次对应Fe2O3还原为Fe3O4以及Fe3O4还原为FeO的两个过程。由于陶瓷表面具有良好的亲水性,同时负载后的氧化铁在其表面有较高的分散性,使得该催化剂的低温脱硫活性较高,适用于燃用中高硫煤的沿海电厂的海水烟气脱硫过程。     

新型氧化铁纳米材料的研究进展

氧化铁纳米材料具有不同的形貌和结构,包括纳米颗粒、纳米棒、纳米带和纳米薄膜等.它们优异的物理和化学性质在众多领域内显示出广阔的应用前景,如催化、磁性材料和生物医学等领域.制备具有新颖形貌和结构的氧化铁纳米材料及其应用研究已经成为纳米材料领域的研究前沿和热点之一.本文综述了新型氧化铁纳米材料的制备、结构以及应用的研究进展,探讨了该研究领域亟待解决的问题以及今后可能的发展前景.