溶胶凝胶-熔盐法制备Cd1-xCoxFe2O4及磁性研究

通过溶胶凝胶-熔盐法以NaCl为熔盐制备了掺杂(Co2+的Cd1-xCOxFe2O4(x=0～0.5)尖晶石型铁氧体.利用XRD、SEM和VSM等手段对样品进行了结构、形貌和磁性表征,并详细讨论了Co2+对Co1-x-CdxFe2O4(x=0～0.5)铁氧体结构和磁性的影响.结果表明:在研究范围内掺杂后仍然能得到单相尖晶石结构铁氧体;样品均为正八面体;比饱和磁化强度随x的增大而增加.     

Friction and adhesion properties of fluorocarbon polymer thin films prepared by magnetron sputtering

Fluorocarbon polymer thin films were deposited onto a SUS302 substrate with a poly(tetrafluoroethylene) (PTFE) target by three different types of r.f. magnetron sputtering systems with strong, weak and unbalanced magnetic fields. Friction and adhesion properties of these polymer thin films were evaluated.Friction coefficient of polymer thin films prepared with strong magnetic field, unbalanced magnetron and without magnetron (r.f. sputtering) was almost the same level, however, that prepared with the weak magnetic field was slightly lower than those of other thin films. Wear durability of polymer thin film increased with increase of the magnetic field.Adhesion strength between these thin films and SUS302 substrate and shear stress were measured by SAICAS. Both of the adhesion strength and shear stress of polymer thin films prepared with r.f. sputtering (without magnetron) were slightly higher than those prepared by magnetron sputtering systems.     

红黄土对水中Cr~(3+)和Cd~(2+)的吸附性能

用天然红黄土作为吸附剂进行了去除水中Cr3+和Cd2+的试验研究,考察了pH值、吸附时间、红黄土投加量对吸附效果的影响,测定了不同pH和不同温度下的吸附等温线。结果表明:红黄土对Cr3+的吸附能力高于对Cd2+的吸附能力,一定条件下,Cr3+的去除率可达99.5%,而Cd2+的去除率最高约63%;吸附行为均符合Lang-muir单分子层吸附模型。根据试验结果,认为红黄土有望成为处理含重金属离子废水的新型吸附材料。     

车间及周边环境部分重金属污染的监测分析方法

样品用HCl+HNO3+HF+HClO3溶解,1∶1 HNO3提取,电感耦合等离子质谱（ICP-MS）测定样品中 Cr、Cd、Pb,建立了车间及周边环境部分重金属污染的监测分析方法,此法可较好的满足重金属污染 Cr、Cd、Pb分析要求。方法具有简单、快速、检出限低、灵敏度高等优点。方法Cr的检出限1.0×10-6,回收率97.06%～101.9%,相对标准偏差1.06%～4.68%。     

The effect of argon pressure on the structural and photocatalytic characteristics of TiO2 thin films deposited by d.c. magnetron sputtering

TiO₂ thin films of 200-300 nm thickness were deposited by d.c. magnetron sputtering onto glass substrates from a semiconducting TiO_2−x target in pure Ar using pressures between 0.1 and 1.0 Pa. The obtained TiO₂ coatings are transparent and have refractive indices between 2.5 and 1.9. Post deposition heat treatment at different temperatures was performed to achieve crystallization of anatase TiO₂. The as-deposited and heat treated films were examined with UV-VIS (transmission), SEM and XRD to investigate the influence of the argon pressure during deposition on the structural development during heat treatment. Additionally, the photocatalytic activity of the films was tested by measuring the decomposition rate of ethanol in a controlled gas atmosphere simulating air, and was related to their respective microstructures.     

The adsorption of Cd(II) ions on sulphuric acid-treated wheat bran

The adsorption of Cd(II) ions which is one of the most important toxic metals by using sulphuric acid-treated wheat bran (STWB) was investigated. The effects of solution pH and temperature, contact time and initial Cd(II) concentration on the adsorption yield were studied. The equilibrium time for the adsorption process was determined as 4 h. The adsorbent used in this study gave the highest adsorption capacity at around pH 5.4. At this pH, adsorption capacity for an initial Cd(II) ions concentration of 100 mg/L was found to be 43.1 mg/g at 25 degrees C for contact time of 4 h. The equilibrium data were analysed using Langmuir and Freundlich isotherm models to calculate isotherm constants. The maximum adsorption capacity (qmax) which is a Langmuir constant decreased from 101.0 to 62.5 mg/g with increasing temperature from 25 to 70 degrees C. Langmuir isotherm data were evaluated to determine the thermodynamic parameters for the adsorption process. The enthalpy change (deltaH(o)) for the process was found to be exothermic. The free energy change (deltaG(o)) showed that the process was feasible. The kinetic results indicated that the adsorption process of Cd(II) ions by STWB followed first-order rate expression and adsorption rate constant was calculated as 0.0081 l/min at 25 degrees C. It was observed that the desorption yield of Cd(II) was highly pH dependent.     

Substrate temperature dependence of the properties of Ga-doped ZnO films deposited by DC reactive magnetron sputtering

Ga-doped zinc oxide (ZnO:Ga) transparent conductive films were deposited on glass substrates by DC reactive magnetron sputtering. The influence of substrate temperature on the structural, electrical, and optical properties of ZnO:Ga films was investigated. The X-ray diffraction (XRD) studies show that higher temperature helps to promote Ga substitution more easily. The film deposited at 350 °C has the optimal crystal quality. The morphology of the films is strongly related to the substrate temperature. The film deposited is dense and flat with a columnar structure in the cross-section morphology. The transmittance of the ZnO:Ga thin films is over 90%. The lowest resistivity of the ZnO:Ga film is 4.48×10⁻⁴ Ω cm, for a film which was deposited at the substrate temperature of 300 °C.     

Formulation of ternary complexes of glyburide with hydroxypropyl-β-cyclodextrin and other solubilizing agents and their effect on release behavior of glyburide in aqueous and buffered media at different agitation speeds

Glyburide, a sulfonylurea derivative, widely used as hypoglycaemic agent. In the present study, an attempt has been made to investigate the most effective third component which can be used with hydroxylpropyl-β-cyclodextrin (HPβCd) to form a ternary complex with glyburide in order to enhance its dissolution rate, as well as reduce the amount of HPβCd used for formulating the binary complex with glyburide. Moreover, the objective of this study was also to develop a discriminatory dissolution media in order to discriminate the effect of the different solubilizing agents used for formulating the ternary complex system. Sodium lauryl sulphate, Poloxamer-188, Polyvinylpyrrolidone K-30, lactose and l-arginine were used to formulate ternary system along with HPβCd and glyburide. The ternary system formulated with glyburide:HPβCd:l-arginine in a proportion of 1:1:0.5 has shown the fastest dissolution rate when compared to other solubilizing agents. Unbuffered aqueous media with stirring speed 50?rpm has produced the most discriminatory dissolution profiles. The DSC thermograms and the powder X-ray analysis revealed the decrease in crystallinity of the drug. This was an indication of amorphous solid dispersion or molecular encapsulation of the drug into the cyclodextrin cavity.     

Chemical substitution reaction between Cu(II) and Hg(II) and hydrous CdS(s)

The chemical reaction between hydrous CdS(s) and Cu(II) and Hg(II) were studied by electrophoretic mobility measurements and adsorption experiments. The results show that cation exchange, following readsorption of the released Cd(II) ions onto the freshly-formed CuS(s) and cadmium hydroxide precipitation reactions occur when CdS particles come into contact with these metal ions which have sulfide precipitates less soluble than CdS(s). The effect of organic ligands on the ion exchange reaction, exemplified by EDTA (a strong complexing ligand) and phthalic acid (a weak complexing ligand), was also investigated. Both organic compounds have little effect on the lattice ion exchange reaction unless a large amount of strong complexing agent is present in the system. The dissolution of CdS(s), however, is slightly hindered in the presence of weak complex former such as phthalic acid and greatly enhanced in the presence of strong complex former such EDTA.     

Characterization of Cd1-xZnxTe (0≤x≤1) Nanolayers Grown by Atomic Layer Deposition on GaSb and GaAs (001) Oriented Substrates

ZnTe, CdTe, and the ternary alloy CdZnTe are important semiconductor materials used widely for the detection of an important range of electromagnetic radiation as gamma ray and X-ray. Although, recently these materials have acquired renewed importance due to the new explored nanolayer properties of modern devices. In addition, as shown in this work they can be grown using uncomplicated synthesis techniques based on the deposition in vapour phase of the elemental precursors. This work presents the results obtained from the deposition of nanolayers of these materials using the precursor vapour on GaAs and GaSb (001) substrates. This growth technique, extensively known as atomic layer deposition (ALD), allows the layers growth with nanometric dimension. The main results presented in this work are the used growth parameters and the results of the structural characterization of the layers by the means of Raman spectroscopy measurements. Raman scattering shows the peak corresponding to longitudinal optical (LO)-ZnTe, which is weak and slightly redshift in comparison with that reported for the ZnTe bulk at 210 cm–1. For the case of the CdTe nanolayer, Raman spectra presented the LO-CdTe peak, which is indicative of the successful growth of the layer. Its weak and slightly redshift in comparison with that reported for the CdTe bulk can be related with the nanometric characteristic of this layer. The performed high-resolution X-ray diffraction (HR-XRD) measurement allows to study some important characteristics such as the crystallinity of the grown layer. In addition, the HR-XRD measurement suggests that the crystalline quality has dependence on the growth temperature.