amorphous selenium red

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Chemistry - Selenium in Nutrition - NCBI Bookshelf

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. Three crystalline forms of selenium occur: alpha-monoclinic, beta-monoclinic, and hexagonal.

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Selenium - McGill University School of Computer Science

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.

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34 - black(vitreous form Crystalline monoclinic selenium ...

Selenium exhibits photovoltaic action, where light is converted directly into electricity, and photoconductive action, where electrical resistance decreases with increased illumination. Selenium exists in several forms, but is usually prepared with an amorphous or crystalline structure. Amorphous selenium is either red (powder form) or

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Development of an Amorphous Selenium-Based …

Amorphous selenium (a-Se) is a promising material for a high-sensitivity photodetector that has low thermal noise and a wide detectable wavelength range that covers visible to the UV [11], as well as X-rays [2–4]. The high sensitivity of a-Se based photodetector is explained by signal enhancement

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Hg Removal - Sulphuric Acid

The selenium filter consists of a porous inert material soaked with selenious acid which is then dried to precipitate red amorphous selenium. H2SeO3 + H2O + 2 SO2 --> Se + 2 H2SO4. The red amorphous selenium reacts with the mercury in the gas to form HgSe. The contact time in the filter is about 1 to 2 seconds.

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Papers with the keyword Amorphous selenium (Page 2) | Read ...

Read papers from the keyword Amorphous selenium with Read by QxMD. ... Generation of nanoparticles was visualized from the appearance of red colour in the selenite supplemented culture medium and broad absorption bands in the UV-vis. Biofabricated nanoparticles were spherical, polydisperse, ranged from 100-183 nm and the average particle size ...

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Sensitivity to red/green/blue illumination of amorphous ...

Amorphous selenium (a-Se) has been studied as an X-ray image detector and low-intensity light camera detector because of its superior avalanche multiplication characteristics.

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Optical Properties of Selenium - IOPscience

The 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.

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Allotropes | Encyclopedia.com

Thus, in addition to amorphous boron, several different allotropes of boron are known, of which three are well characterized. These are red crystalline α-rhombohedral boron, black crystalline β-rhombohedral boron (the most thermodynamically stable allotrope), and black crystalline β-tetragonal boron.

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Selenium | Se - PubChem

Selenium can be prepd with either amorphous or crystalline structure. ... Amorphous is either red, in powder form or black, in vitreous form. Crystalline monoclinic selenium is deep red; crystalline hexagonal form, the most stable variety, is a metallic gray.

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Selenium

Selenium 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.

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Facts About Selenium - Live Science

In the present work, a vapor transport and fast quenching deposition method is used for the coating of inner walls of fused silica tubes with amorphous selenium – in particular, with the red amorphous allotrope – since the quenching of selenium vapors at low temperatures leads to the production of amorphous (red) selenium,, .

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Chemistry - Selenium in Nutrition - NCBI Bookshelf

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. Three crystalline forms of selenium occur: alpha-monoclinic, beta-monoclinic, and hexagonal.

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Selenium | Define Selenium at Dictionary.com

Selenium definition, a nonmetallic element chemically resembling sulfur and tellurium, occurring in several allotropic forms, as crystalline and amorphous, and having an electrical resistance that varies under the influence of light.

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Selenium - Periodic Table of Elements and Chemistry

Crystalline 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).

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Photoinduced changes in amorphous selenium - Canadian ...

Photoinduced phenomena in thin films of amorphous selenium (a-Se) have been a subject of intensive researches so far. Thin films of a-Se were deposited on corning glass by thermal evaporation, with several thicknesses. The influence of light exposure, with different colors (blue or red or natural white light), on the optical and structural properties of a-Se thin films was carried out by using ...

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Selenomonas | Article about Selenomonas by The Free Dictionary

Amorphous (red) powdery and colloidal selenium (density 4.25 g/cm 3 at 25°C) are obtained by such methods as the reduction of selenious acid (H 2 SeO 3) from solution and the rapid cooling of selenium …

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Allotropy of Selenium - Atomistry

Crystalline Varieties of Selenium Monoclinic Selenium Monoclinic Selenium is obtained when a carbon disulphide solution of amorphous selenium is allowed to crystallise, for example by evaporation or by keeping red amorphous or vitreous selenium in contact with carbon disulphide.

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Amorphous selenium based photodetector driven by field ...

Photoresponse to red, green, and blue illuminations, however, is mandatory for the practical use of the future applications ultrahigh sensitivity camera. Amorphous selenium (a-Se) has band gap of 2.0 eV without incorporation of Te. 19 19. J. A.

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Selenium, Physical and Chemical Properties | SpringerLink

Selenium is a by-product of the extraction of copper and nickel from their sulfide ores. It is concentrated in the anodic slimes of electrorefining of these metals. Red amorphous selenium is produced by reducing selenous acid with sulfur dioxide, by crystallization from solution, or by quenching of selenium vapor or molten selenium.

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Allotropes | Encyclopedia.com

Thus, in addition to amorphous boron, several different allotropes of boron are known, of which three are well characterized. These are red crystalline α-rhombohedral boron, black crystalline β-rhombohedral boron (the most thermodynamically stable allotrope), and black crystalline β-tetragonal boron.

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Selenium

Selenium 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 slenium is a deep red; crystalline hexagonal selenium, the most stalbe variety, is a metallic gray.

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Preparation of red amorphous selenium - Xerox Corporation

 · Red 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.

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Comparison of the Phonon Density of States of T1igonai ...

Comparison of the Phonon Density of States of T1igonai, Vitreous, and Red Amorphous Selenium F. Gompf Kernforschungszentrum Karlsruhe, Institut fUr Angewandte Kernphysik D-7500 Karlsruhe, Fed. Rep. of Germany 1. Introduction With the help of inelastic neutron scattering we …

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ChemicalDesk.Com: Selenium dioxide

SeO 2 is an important reagent in organic synthesis. Oxidation of paraldehyde (acetaldehyde trimer) with SeO 2 gives glyoxal and the oxidation of cyclohexanone gives cyclohexane-1,2-dione. The selenium starting material is reduced to selenium, and precipitates as a red amorphous …

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Selenium | Article about selenium by The Free Dictionary

Amorphous (red) powdery and colloidal selenium (density 4.25 g/cm 3 at 25°C) are obtained by such methods as the reduction of selenious acid (H 2 SeO 3) from solution and the rapid cooling of selenium …

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Selenium | The Periodic Table at KnowledgeDoor

Our selenium page has over 260 facts that span 106 different quantities. Each entry has a full citation identifying its source. Areas covered include atomic structure, physical properties, atomic interaction, thermodynamics, identification, atomic size, crystal structure, history, abundances, and nomenclature.

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Selenium - Wikipedia

Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. When rapidly melted, it forms the black, vitreous form, usually sold commercially as beads.

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