Annealing effect on the structural and magnetic properties of nickel ferrite thin films

Nickel ferrite is a soft magnetic material with inverse spinel structure. Soft ferrite films are used in microwave devices, integrated planar circuits, etc., because of their high resistivity. In this work, thin films of nickel ferrite were deposited on Si (100) substrate by using pulsed laser deposition (PLD) technique. The thickness of the film was measured by surface profilometer and also by X‐ray reflectivity (XRR). The films were annealed at three different temperatures to observe the effect on the structural and magnetic properties of the film. The films were characterised by X‐ray diffraction (XRD), Raman spectroscopy and vibrating sample magnetometer (VSM) to study the structural and magnetic properties. Copyright © 2010 John Wiley & Sons, Ltd.     

Melanin‐Containing Films: Growth from Dopamine Solutions versus Layer‐by‐Layer Deposition

Films formed by oxidation of dopamine are of interest for functionalisation of solid–liquid interfaces owing to their versatility. However, the ability to modulate the properties of such films, for example, permeability to ionic species and the absorption coefficient, is urgently needed. Indeed, melanin films produced by oxidation of dopamine absorb strongly over the whole UV/Vis part of the electromagnetic spectrum and are impermeable to anions even for a film thickness as low as a few nanometers. Herein we combine oxidation of dopamine to produce a solution containing dopamine–melanin particles and their alternating deposition with poly(diallyldimethylammonium chloride) to produce films which have nearly the same morphology as pure dopamine–melanin films but are less compact, more transparent and more permeable to ferrocyanide anions.     

Adsorptive Stripping Determination of Scandium(III) with Mordant Blue 9 on Silver Amalgam Film Electrode

A new adsorptive stripping voltammetric method for the determination of trace scandium(III) based on the adsorption of scandium(III)‐mordant blue 9 complex on the cyclic renewable mercury film silver based electrode (Hg(Ag)FE) is presented. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 2 nM (0.09 μg L^?1) to 90 nM (4 μg L^?1) for a preconcentration time of 45 s, with correlation coefficient of 0.9995. For a Hg(Ag)FE with a surface area of 7.9 mm² the detection limit for a preconcentration time of 90 s is as low as 5 ng L^?1. The repeatability of the method at a concentration level of the analyte as low as 0.2 μg L^?1, expressed as RSD is 1.9 % (n=5). The proposed method was successfully applied and validated by studying the certified reference material (CRM 320 – river sediment) and natural samples with simultaneous recovery of Sc(III) from spiked water and sediment samples.     

Tin oxide coating on polytetrafluoroethylene films in aqueous solutions

Polytetrafluoroethylene (PTFE) films were successfully coated with tin oxide in aqueous solutions. Tin oxide was crystallized in the solution and formed nanocrystal coatings on the polymer films. The coatings consisted of SnO₂ and SnO crystals. They were assemblies of tin oxide nanosheet of about 10 to 50 nm in size and about 5 nm in thickness. The nanocrystal films can be exfoliated from the PTFE substrates. Tin oxide nanocrystal films had a rough liquid surface and a dense substrate‐side surface. Transparency of PTFE films coated with tin oxide was same as that of bare PTFE films in the range from 400 to 800 nm. The PTFE films coated with tin oxide nanocrystals can be pasted on desired substrates. Copyright © 2009 John Wiley & Sons, Ltd.     

Nanofibrous polyaniline thin film prepared by plasma‐induced polymerization technique for detection of NO2 gas

A nanofibrous polyaniline (PANI) thin film was fabricated using plasma‐induced polymerization method and explored its application in the fabrication of NO₂ gas sensor. The effects of substrate position, pressure, and the number of plasma pulses on the PANI film growth rate were monitored and an optimum condition for the PANI thin film preparation was established. The resulting PANI film was characterized with UV–visible spectrophotometer, FTIR, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The PANI thin film possessed nanofibers with a diameter ranging from 15 to 20 nm. The NO₂ gas sensing behavior was studied by measuring the change in electrical conductivity of PANI film with respect to NO₂ gas concentration and exposure time. The optimized sensor exhibited a sensitivity factor of 206 with a response time of 23 sec. The NO₂ gas sensor using nanofibrous PANI thin film as sensing probe showed a linear current response to the NO₂ gas concentration in the range of 10–100 ppm. Copyright © 2009 John Wiley & Sons, Ltd.     

纳米结构ZnO在TiO_2薄膜上的电化学沉积及其表征

在三电极体系中,以硝酸锌水溶液作为电解液,采用阴极还原电沉积法成功实现了一维纳米结构ZnO阵列在TiO2纳米粒子/ITO导电玻璃薄膜基底上的沉积,并通过XRD、SEM、EDS和PL光谱等方法对样品进行了表征.重点研究了薄膜基底、电解液浓度、沉积时间、六次亚甲基四胺(HMT)的引入对ZnO沉积及其发光性质的影响.结果显示:与ITO玻璃基底相比,ZnO更易于在TiO2纳米粒子薄膜上实现电化学沉积.ZnO属于六方晶系的铅锌矿结构,并且沿着c-轴方向表现出明显的择优化生长,以形成垂直于基底的ZnO纳米棒阵列.延长沉积时间、增加电解液浓度和引入一定量的HMT等均对ZnO的生长有促进作用,进而使其纳米棒的结晶度和取向程度提高,进而解释了所得的薄膜分别约在375和520nm处表现出ZnO的强而窄的带边紫外光发射峰和弱而宽的表面态绿光发射带.     

Li_2CO_3添加剂对石墨电极性能的影响

运用电化学阻抗谱(EIS)和循环伏安法(CV)研究了在1mol/LLiPF6-EC(碳酸乙烯酯):DMC(碳酸二甲酯)电解液中添加Li2CO3对石墨电极性能的影响及机制.CV研究结果表明,在1mol/LLiPF6-EC:DMC电解液中添加Li2CO3能够有效抑制石墨电极首次充放电过程中碳酸乙烯酯(EC)的单电子还原过程,即还原分解产生乙烯和碳酸锂的过程,进而改善石墨电极的电化学循环性能.EIS研究结果表明,在添加Li2CO3的1mol/LLiPF6-EC:DMC电解液中,石墨电极表面的固体电解质相界面膜(SEI膜)具有较强的黏弹性,可以更好地适应锂离子嵌入过程中石墨颗粒体积的微小变化,从而使锂离子的嵌入过程更容易进行.     

Anodic film formation on binary Al?Mg and Al?Ti alloys in nitric acid

Nitric acid is commonly used for surface treatments of aluminium alloys. It is used to clean the surfaces after alkaline etching; it has application in chemical polishing and is also used for electrograining. The majority of these treatments undergo the application of anodic polarisation that results in formation of anodic oxide film. However, little is known about the behaviour of aluminium containing magnesium or titanium in solid solution under such conditions. To reveal the effects of magnesium and titanium alloying additions on anodic film formation in nitric acid, Al‐1800 ppm Mg and Al‐800 ppm Ti alloys were investigated. It was found that porous alumina film developed on the surfaces with reduced efficiency of 40%, due to the reactive nature of nitric acid to alumina. The presence of magnesium and titanium in aluminium had little influence on the efficiency of film growth, as confirmed by the relatively similar thicknesses of oxide formed on binary alloys and aluminium. However, incorporation of magnesium ions into the alumina film led to development of a high‐population density of localised voids near the alloy/film interface. An increased titanium content was found in the film regions close to the alloy/film interface, indicating its oxidation. Copyright © 2009 John Wiley & Sons, Ltd.     

氮掺杂二氧化钛-氧化镍双层薄膜的光电致色特性

以金属钛为靶材、O2/N2/Ar混合气氛为溅射气体,在导电玻璃(ITO)表面磁控溅射一层薄膜,再经300-500℃退火处理制备了氮掺杂TiO2薄膜.采用X射线衍射(XRD)、X光电子能谱(XPS)、扫描电子显微镜(SEM)和紫外-可见吸收光谱等对薄膜的微观结构、光学特性和光电化学性能等进行了研究.进而采用化学沉积的方法在TiO2-xNx薄膜表面沉积上一层多孔NiO薄膜,研究表明,制备的ITO/TiO2-xNx/NiO双层薄膜具有明显的光电致色特性,400℃退火处理的氮掺杂TiO2薄膜具有最高的光电流响应,经氙灯照射1h后,薄膜从无色变成棕色,500nm波长处光透过率从79.0%下降至12.6%.