Apr 23, 2014 Amongst its various forms, the red amorphous selenium is with biological activity and effects similar to those of sodium selenite but with much lower acute toxicity , . It was considered the most potent chemical form to the artificial selenium enrichment. Therefore, the red amorphous selenium has attracted much attention –.
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A suspension of nanoparticles of BSA-stabilized red amorphous elemental selenium (Se) or an aqueous solution of sodium selenite was repeatedly administered by oral gavage for 28 days at 0.05 mg kg(-1) bw per day (low dose) or at 0.5 mg kg(-1) bw per day …
More DetailsJun 08, 2001 The red, amorphous selenium has a deformed chain structure, high resistivity (ρ=10 13 –10 16 Ω cm) and upon heat treatment transforms to stable hexagonal modification. In recent years, the great interest in various allotropes of selenium and their interconversion is due to its use in electronics and solid-state technology [9] , [10] , [13 ...
More DetailsFeb 01, 2008 Sensitivity to red/green/blue illumination of amorphous selenium based photodetector driven by nitrogen (N)-Doped CVD diamond Author links open overlay panel Nanako Kato a Tomoaki Masuzawa a Yuki Kudo a Yuka Kuwajima a Hisato Yamaguchi a Ken Okano a Takatoshi Yamada b Ichitaro Saito c Tim Butler c Nalin L. Rupesinghe c Gehan A.J. Amaratunga c
More DetailsThe absorption coefficient of amorphous selenium has been measured in the ultra-violet, visible and near infra-red spectral regions. The transmission coefficients of several single crystals of selenium have been measured and an estimate made of the absorption coefficient in the wavelength range 0.68 to 2.0 μ.
More DetailsAmorphous selenium is either a reddish powder or a black, vitreous solid; crystalline selenium is either red or gray, depending on the crystal structure. This element resembles sulfur in its various forms and in its compounds. Selenium has many electrical properties, being both photovoltaic, where light converts to electricity, and ...
More DetailsRed amorphous selenium nanoparticles have been successfully synthesized by the reaction of 500 mg dm-3 Se (sodium selenite) solution with 10 g dm-3 ascorbic acid solution at room temperature, and ...
More DetailsA new amorphous selenium (a-Se) digital radiography detector is introduced. The proposed detector generates a charge image in the a-Se layer in a conventional manner, which is stored on electrode pixels at the surface of the a-Se layer. A novel method, called photoconductively activated switch (PAS) …
More DetailsF. Gompf: The phonon densities of states of trigonal, vitreous and red amorphous selenium, J. Phys. Chem. Solids 42, 539–544 (1981) CrossRef Google Scholar B. Pejova, I. Grozdanov: Solution growth and characterization of amorphous selenium thin films: Heat transforms to nanocrystalline gray selenium thin films, Appl. Surf. Sci. 177 , 152 ...
More DetailsNov 29, 2016 Amorphous selenium is either red, in powder form, or black, in vitreous, or glassy, form. The most stable form of the element, crystalline hexagonal selenium, is …
More DetailsSelenium characteristics. Selenium is found in different allotropic forms , in which selenium becomes amorphous and classified into three. The first is the vitreous (black), which is obtained by cooling the selenium in its liquid state by changing its composition, for example, now the selenium will need to be 180 C to be able to melt , its density is around 4.28 g .
More DetailsSelenium can be prepared with either an amorphous or crystalline structure. The color of amorphous selenium is either red, in powder form, or black, in vitreous form. Crystalline monoclinic selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is a metallic gray.
More DetailsCrystalline monoclinic selenium is a deep red color. Amorphous selenium is red in powder form and is black in vitreous form. Gray crystalline ‘metallic’ selenium conducts electricity better in the light than in the dark (photoconductive) and it can convert light directly into electricity (photovoltaic).
More DetailsSep 29, 2020 Amorphous selenium (a-Se) has a complicated molecular structure with overcoordinated defects and dangling bonds. This light-sensitive structure can undergo significant changes including bond breakage, reconnection, and defect formation upon illumination with above-bandgap light. Light sensitivity makes a-Se a unique system to study the role of surface structure and …
More DetailsElemental selenium, Selenium alloy Amorphous or crystalline, red to gray solid. [Note: Occurs as an impurity in most sulfide ores.]
More DetailsThe selenous acid is finally bubbled with sulfur dioxide producing elemental red amorphous selenium. Selenium produced in chemical reactions invariably appears as the amorphous red form-- an insoluble brick red powder. When this form is rapidly melted, it forms the black, vitreous form which is usually sold industrially as beads. ...
More DetailsAmorphous Selenium (a-Se) Many of the detector systems being developed in our lab use a photoconductor called amorphous Selenium (a-Se) as the X-ray detector material, i.e. the material which 'catches the X-rays', and converts them to either charge or lower energy photons.
More DetailsAug 06, 2021 Selenium nanoparticles were amorphous and exhibited a polygonal-like nanostructure. ... , this is a typical characteristic of an amorphous phase of SeNPs which agrees well with the brick red colour which was observed after synthesis as indicated in Fig. 1D insert. Amorphous SeNPs synthesized using different plant extract have also been ...
More DetailsAmorphous-selenium (a-Se) based photodetectors are promising candidates for imaging devices, due to their high spatial resolution and response speed, as well as extremely high sensitivity enhanced by an internal carrier multiplication. In addition, a-Se is reported to show sensitivity against wide variety of wavelengths, including visible, UV and X-ray, where a-Se based flat-panel X-ray ...
More DetailsAn amorphous (noncrystalline), red, powdery form of selenium results when a solution of selenious acid or one of its salts is treated with sulfur dioxide. If the solutions are very dilute, extremely fine particles of this variety yield a transparent red colloidal suspension.
More Detailsadshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A
More DetailsSelenium is obtained from lead, copper and nickel refining. Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers, also colours glass red. The price of 99.999 % pure amorphous selenium shot is 301.80 € for 1000 g.
More DetailsSelenium exists in a number of allotropic forms. Allotropes are forms of an element with different physical and chemical properties. One allotrope of selenium is an amorphous red powder. Amorphous means without crystalline shape. A lump of clay is an example of an amorphous material. A second allotrope of selenium has a bluish, metallic ...
More DetailsElemental selenium is, thus, vitreous at 31 C-230 C and is a hard and brittle glass below 31 C. A red particulate form, colloidal amorphous selenium, can be prepared by the reduction of aqueous solutions of selenious acid; however, this form becomes crystalline at temperatures above 60 C.
More DetailsSelenium exists in several allotropic forms. Three distinct forms are (1)amorphous (2)crystalline and (3)metallic:Amorphous forms exhibit two colors, occurring as a red powder of density 4.26g/cm3 that has a hexagonal crystal structure and a black vitreous solid of density 4.28g/cm3. The red amorphous selenium converts to the black form on ...
More DetailsSelenium occurs in an amorphous form (red selenium) or as a grey silvery metal. The amorphous form is a glass-like solid while the metal form is soft. Under influence of light the electrical conductivity increases. Photoconductivity is an outstanding physical property of crystalline selenium. Applications
More DetailsRed amorphous selenium is obtained by precipitating selenium from a solution of selenious acid in methanol or ethanol with hydrazine or a soluble salt thereof at a temperature between about -20 C....
More Detailsformed by the rapid cooling of liquid selenium. Red amorphous selenium is colloidal and is formed in reduction reactions (Hoffmann and King 1997). Important selenium oxidation states are -2, 0, +4, and +6. The chemical properties of selenium are similar to sulfur. Selenium combines with metals and many nonmetals directly or in aqueous solution.
More DetailsRed amorphous selenium is obtained by precipitating selenium from a solution of selenious acid in methanol or ethanol with hydrazine or a soluble salt thereof at a temperature between about -20 C. and the freezing point of the solution. Furthermore, the stable red amorphous selenium …
More DetailsThe absorption coefficient of amorphous selenium has been measured in the ultra-violet, visible and near infra-red spectral regions. The transmission coefficients of several single crystals of...
More DetailsThe color of amorphous selenium is either red (in powder form) or black (in vitreous form). Crystalline monoclinic selenium is a deep red and crystalline hexagonal selenium (the most stable variety) is a metallic gray. Selenium burns in air and is uneffected by water, but …
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