Antimony

About: Antimony is a(n) research topic. Over the lifetime, 11450 publication(s) have been published within this topic receiving 155660 citation(s). The topic is also known as: Sb & element 51.

A modified single solution method for the determination of phosphate in natural waters

Abstract: A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.

Antimony in the environment: a review focused on natural waters: I. Occurrence

Abstract: Antimony is ubiquitously present in the environment as a result of natural processes and human activities. It exists mainly as Sb(III) and Sb(V) in environmental, biological and geochemical samples. Antimony and its compounds are considered to be priority pollutants interest by the USEPA and the EU. In this first review paper on antimony occurrence in natural waters, 420 papers on freshwaters, marine waters, estuaries, soils, and sediments have been reviewed. All data are quoted from the original sources. Typical concentrations of total dissolved antimony are usually less than 1.0 μg/l in non-polluted waters. When redox speciation determinations are performed, most studies report the dominance of Sb(V) under oxic conditions. However, the presence of significant proportions of Sb(III) is sometimes detected. This is in contrast with thermodynamic equilibrium predictions and discrepancies are often attributed to biological activity or kinetic effects but proofs are lacking. Similarly, the existence of Sb(V), although not thermodynamically predicted, is often reported under anoxic conditions. Low concentrations of methylated antimony species are mentioned in a few studies. Antimony is not considered to be a highly reactive element in oceans, with concentrations of the order of 200 ng/l. In estuarine waters, both conservative and non-conservative behaviours are reported depending on the estuaries' characteristics. Elevated concentrations of antimony in soils and sediments are either related to anthropogenic sources or associated with high arsenic concentrations in sulfidic ores. Antimony appears to be highly unreactive in soils. Low accumulation factors are reported in algae. Airborne supply of antimony to aquatic and terrestrial systems seems to be important in systems far from direct pollution sources. However, the limited available data do not allow firm conclusions to be drawn on the reactivity and cycling of the element in natural systems and a list of research priorities is given.

Visible-light-response and photocatalytic activities of TiO2 and SrTiO3 photocatalysts codoped with antimony and chromium

Abstract: TiO2 and SrTiO3 codoped with antimony and chromium showed intense absorption bands in the visible light region and possessed 2.2 and 2.4 eV of energy gaps, respectively. TiO2 codoped with antimony and chromium evolved O2 from an aqueous silver nitrate solution under visible light irradiation, while SrTiO3 codoped with antimony and chromium evolved H2 from an aqueous methanol solution. The activity of TiO2 photocatalyst codoped with antimony and chromium was remarkably higher than that of TiO2 doped with only chromium. It was due to that the charge balance was kept by codoping of Sb5+ and Cr3+ ions, resulting in the suppression of formation of Cr6+ ions and oxygen defects in the lattice which should work as effectively nonradiative recombination centers between photogenerated electrons and holes.

Doping by large-size-mismatched impurities: the microscopic origin of arsenic- or antimony-doped p-type zinc oxide.

Abstract: Based on first-principles calculations, a model for large-size-mismatched group-V dopants in ZnO is proposed. The dopants do not occupy the O sites as is widely perceived, but rather the Zn sites: each forms a complex with two spontaneously induced Zn vacancies in a process that involves fivefold As coordination. Moreover, an As(Zn)-2V(Zn) complex may have lower formation energy than any of the parent defects. Our model agrees with the recent observations that both As and Sb have low acceptor-ionization energies and that to obtain p-type ZnO requires O-rich growth or annealing conditions.

Enhanced thermoelectric figure-of-merit in p-type nanostructured bismuth antimony tellurium alloys made from elemental chunks.

Abstract: By ball milling alloyed bulk crystalline ingots into nanopowders and hot pressing them, we had demonstrated high figure-of-merit in nanostructured bulk bismuth antimony telluride. In this study, we use the same ball milling and hot press technique, but start with elemental chunks of bismuth, antimony, and tellurium to avoid the ingot formation step. We show that a peak ZT of about 1.3 in the temperature range of 75 and 100 °C has been achieved. This process is more economical and environmentally friendly than starting from alloyed bulk crystalline ingots. The ZT improvement is caused mostly by the lower thermal conductivity, similar as the case using ingot. Transmission electron microscopy observations of the microstructures suggest that the lower thermal conductivity is mainly due to the increased phonon scattering from the increased grain boundaries of the nanograins, precipitates, nanodots, and defects. Our material also exhibits a ZT of 0.7 at 250 °C, similar to the value obtained when ingot was used. This study demonstrates that high ZT values can be achieved in nanostructured bulk materials with ball milling elemental chunks, suggesting that the approach can be applied to other materials that are hard to be made into ingot, in addition to its advantage of lower manufacturing cost.