Papers by Keyword: Antimony

Abstract: The sensing properties of semiconductive gas sensors originate from the resistance variation of depletion layer in each grain of the element. One of the most fundamental factors in this type of sensors is the width of depletion region. In this work, the antimony-doped tin oxide thin films for gas sensors are prepared via sol-gel routes on alumina substrates. The influence of antimony addition amount on electrical resistance of thin films is concluded. The relationship is plotted in the coordinates of logarithmic resistance against doping amount. On the basis of Schottky barrier model, a novel method is proposed to evaluate the width of depletion layer of semiconductive gas sensors by using the first order derivative of logarithmic resistance with respect to doping amount. Thus, the depletion layer width of the prepared antimony-doped thin film is calculated and its influencing factor is also discussed.

Abstract: In the course of our investigations, AlSi8Cu3 foundry alloy was alloyed in different strontium and antimony concentrations. The mechanical properties of structure developed during the given cooling conditions as well as the effect of strontium and antimony on the modification of eutectic Si were investigated by a computer image analysis and by using a scanning electron microscope. Samples with a wall-thickness of 8 mm cast in the course of the experiment-series were used for our investigations. A part of our long-term research work is described in our present paper.

Abstract: Antimony and arsenic are recognized to be toxic carcinogens. With the development of chemical industry, antimony and arsenic pollution problems are becoming more and more serious in soil. This paper described speciation analysis of antimony and arsenic in soil in the latest technical progress. Speciation analysis of arsenic and antimony which use joint techniques and non joint techniques are summarized. This paper also introduced various remediation technologies for antimony and arsenic contaminated soil. Finally, the trend for future technical development in remediation of antimony and arsenic in contaminated soils and speciation analysis is prospected.

Abstract: The Al-Si cast alloy mechanical properties and microstructure depends on the chemical composition; melt treatment conditions, solidification rate, casting process and the applied thermal treatment. Modification can be achieved by several methods as faster solidification, mould vibration, and melt inoculation by using chosen elements like Sr, Na, Sb, etc. Present work is focused on study of the effect of Sb-modification (with AlSb10 from 0 up to 300 ppm) on the structure and mechanical properties in AlSi7Mg0.3 cast alloy. AlSi7Mg0.3 alloy can be used for high temperature casting (e.g. engine, pistons) therefore is necessary to determine the properties at higher temperature. The mechanical properties were evaluated at room (21 °C) and 260 °C. The results show that the modification of experimental material is important. Experimental alloy has by optimal modification (50 ppm Sb) UTS at 260 °C above 100 MPa.

Abstract: Gas sensitivity of Sb-doped SnO₂ nanograins co-precipitated respectively from ethanol and de-ionized water has been compared. Gas sensing stability of the Sb-SnO₂ from ethanol (SnO₂-E) was significantly superior to that of Sb-SnO₂ from de-ionized water (SnO₂-W): working temperature of sensor using SnO₂-E was as high as 400 °C, whereas, 250 °C, for sensor using SnO₂-W. Furthermore, resistance (R) of SnO₂-E was less affected by annealing temperature: the ratio of air resistance annealed at 800 °C (R800) to 400 °C (R400) for SnO₂-E and SnO₂-W was 8 (4 kΩ/0.5 kΩ) and 1.4×105, 100 MΩ/0.7 kΩ) respectively.

Abstract: Al-Mg₂Si in-situ composite have received wider attention due to their improved properties which mark them as attractive candidate to manufacture most of automotive and aerospace components. Result show that the melt treatment of the in-situ composite by addition of antimony caused to refining the morphology of primary Mg₂Si reinforcement which would expect to improve the mechanical properties. Effect of Sb on the characteristics parameters of Mg₂Si particles have been investigated by thermal and microstructural analysis. The result has revealed that addition of 0.8 wt.% Sb produced optimum refinement effect on the morphology as coarse structure has been changed to polygon one. The result also showed depression with nucleation temperature, T_N and growth temperature, T_G which also correspond to the refinement effect.

Abstract: The modified Tessier method was used in the present study to analyze the antimony (Sb) speciation in suspended solids in mining wastewater from Ban-po Antimony Mine in Guizhou province. It was found that the residual fraction and the soluble fraction are the highest and the lowest in the five Sb fractions, accounting for 62.5% and 3% of the total respectively. The order of the five Sb fractions is: the residual fraction > the reduced fraction > the oxidation fraction > the acid-extractable fraction > the soluble fraction. The antimony soluble form in aqueous solution is mainly Sb (V), about 90% of the total. The results from the analysis by X-ray diffraction and scanning electron microscopy showed that the major crystalline forms of suspended solids are K-Mg-Fe-Al-Si-O-H₂O, Cu₃SbS₄, 3CaO·2Sb₂O₅·8H₂O, SiO₂ and the content of antimony element is approximately 2.55%.

Abstract: In this work we show the effect of various concentrations of strontium and antimony on the level of modification in the Al-Si alloy. The scale of the modification rate was determined in two ways: thermal analysis was performed and the images of the samples. The eutectic temperature registered during the analysis were compared to the eutectic temperature of the unmodified alloy and on the basis of them was determined which samples are registered as modified, which are not. On the basis of the results of the cooling curves the partially modified category was introduced, if the ΔT value is less than 9°C and more than 7.5°C. The samples made of the alloys were examined with a computer image analysis and the samples were grouped on the basis of the size of the eutectic silicon phases. The aim of our research work was the examination of cross-effects of strontium and antimony.

Abstract: Taking antimony powder with 75μm of average particle size as raw material, the antimony nanoparticles were synthesized by mechanical ball milling. Crystalline structure, morphology and particle size of the antimony nanoparticles were characterized by XRD, TEM and FT-IR. The effect of milling mediums and ball milling speed on results antimony nanoparticles were studied using dry grinding and wet grinding methods. The results show that the antimony nanoparticles can be prepared successfully by wet process of ball milling. When the ball milling speed is 150 r/min and the milling mediums is a composites of distilled water and OP-10, the best antimony nanoparticles were prepared, which is high dispersibility and the average particle size is 10 nm.

Abstract: Studies based on electrocrystallization of antimony were carried out to evaluate the effects of current density and antimony concentration in the electrolytic bath on cathodic current efficiency, energy consumption, and quality of the deposits during electrowinning of antimony from Sb₂O₃-HCl and Sb₂S₃-NaOH systems. In acidic bath, current efficiency for electrodeposition of antimony increases with the increase in current density till 150 A/m², beyond which it follows a trend of gradual diminution. On varying antimony concentration in the bath, current efficiency was found to improve significantly and the optimum antimony concentration in Sb₂O₃-HCl system was evaluated to be about 60 g/L. In alkaline bath, current efficiency was observed to be maximum at 50 A/m² and further, with the increase in current density it progressively decreases. However, energy consumption for electrowinning of antimony in both of the baths gradually increases with the increase in current density. At a current density less than 150 A/m², alkaline bath was found to be more current efficient in comparison to the acidic bath. Crystallographic studies by XRD, imaging by optical microscopic technique and morphological studies by SEM were also carried out to differentiate antimony deposits obtained from acidic and alkaline baths.