Selenium - periodictable.ru

Grey crysstalline selenium Grey selenium in glass sphere. Crystals of gray Selenium. Granules of amorphous selenium (4N) Ingot of amorphous selenium (99.5+%) Ingot of glassy selenium. Red selenium. Selenium rectifiers. Directionally solidified grey Selenium. Monoclinic Selenium crystals. Has dark red color in transmitting light.

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Selenium - Wikipedia

Selenium (Redirected from Seleniun) Read in another language Watch this page Edit ...

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Selenium dioxide - Wikipedia

The selenium starting material is reduced to selenium, and precipitates as a red amorphous solid which can easily be filtered off. This type of reaction is called a Riley oxidation. It is also renowned as a reagent for "allylic" oxidation, a reaction that entails the following conversion

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ChemicalDesk.Com: Selenium dioxide

Sep 22, 2011· 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 solid which can easily be filtered off.

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Amorphous selenium flat panel detectors for medical ...

Amorphous selenium flat panel detectors for medical applications. ... edge found to be red‐shifted along with a sharp decrease in optical band gap (1.74‐0.82), with the increasing fraction of ...

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A Medley of Potpourri: Selenium

Jul 17, 2018· 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. The structure of black selenium is irregular and complex and consists of …

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Preparation of red amorphous selenium - Xerox Corporation

Feb 22, 1977· 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. Furthermore, the stable red amorphous selenium may contain a halogen.

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Transformations of red amorphous and monoclinic selenium ...

INTRODUCTION THE STRUCTURE of red amorphous selenium and its transformations are not well known. Mondain-Monvaltl] and Richter et al.[2] assumed that red amorphous and vitreous selenium which has been subject to many investigations [3,4] differ from each other only …

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2SWLFDO3URSHUWLHVRI6HOHQLXP - iopscience.iop.org

of amorphous selenium in the visible spectral region. The absorption measure- ments were made on films of selenium obtained by cathodic sputtering in high vacuum. In the determination of the refractive index Wood used three thin prisms of selenium in the wavelength region 0.76 to 0.60~ and sputtered films in the region 0.60 to 0940p.

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Preparation of red amorphous selenium - Xerox Corporation

May 04, 1976· 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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selenium - webref.org

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

Feb 01, 2008· Read "Sensitivity to red/green/blue illumination of amorphous selenium based photodetector driven by nitrogen (N)-Doped CVD diamond, Diamond and Related Materials" on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.

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Selenium Se (Element 34) of Periodic Table | Periodic ...

Selenium is a non metallic chemical element exists in several allotropic forms, although three are generally recognized. In chemical activity and physical properties it resembles sulfur and tellurium. It can be prepared with either an amorphous or a crystalline structure. The color of amorphous selenium is either red (in powder form) or black (in vitreous form).

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Facts About Selenium | Live Science

Amorphous 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.

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Periodic Table of Elements: Los Alamos National Laboratory

Selenium can be prepared with either an amorphous or a 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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Selenium (Se) Metal & Selenium Powder - reade.com

Amorphous 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 ...

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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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4. CHEMICAL AND PHYSICAL INFORMATION - atsdr.cdc.gov

amorphous selenium, which exists in black and red forms. Black amorphous selenium is vitreous and is formed 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.

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Interaction of elemental mercury with selenium surfaces ...

The adsorption behavior of 197Hg and 183–185Hg on red amorphous selenium (red a-Se) and trigonal selenium (t-Se) was investigated experimentally by off-line and on-line gas chromatographic methods,...

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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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Selenium - Periodic table

Oct 11, 2013· Amorphous-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 ...

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US3954951A - Preparation of red amorphous selenium ...

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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Amorphous, Crystalline and Crystalline/Amorphous Selenium ...

Selenium is applied as the cathode material of lithium/selenium (Li–Se) battery, which has high theoretical volumetric capacity density (3253 mA h·cm–3) and high output voltages. However, it has a low melting point (494 K) and a large sensitivity to thermal treatment, which often result in the phase transition between crystalline Se (trigonal phase) and amorphous Se during the charge ...

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Solution growth and characterization of amorphous selenium ...

Jun 08, 2001· The best fit of (αhν) 1/n versus the photon energy, in the case of both amorphous and hexagonal selenium thin films, was obtained for n= 1 2. The extrapolation of the linear part gave band gap energy of 2.0 eV for the amorphous, red selenium thin films, while for gray ones it …

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Structural and Spectral Features of Selenium Nanospheres ...

The end products of these reactions are the red, amorphous or monoclinic allotropes of Se(0), which accumulate in spent medium because the microorganisms reduce the 10 to 20 mM selenate or selenite provided to Se(0). Respiratory reductases for Se oxyanions contain molybdenum and are associated with the plasma membrane .

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Se | Selenium - PubChem

Selenium can be prepared with either an amorphous or a 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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Flat panel detector - Wikipedia

Flat panel detectors are a class of solid-state x-ray digital radiography devices similar in principle to the image sensors used in digital photography and video. They are used in both projectional radiography and as an alternative to x-ray image intensifiers (IIs) in fluoroscopy equipment.

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Selenium - what is it? The chemical element is selenium ...

Amorphous (powdery, colloidal and vitreous forms of selenium). Amorphous red amorphous selenium modification. What it is? One of the unstable modifications of the element. Powdered and colloidal forms of selenium are obtained by reducing the substance from a …

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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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selenium Flashcards | Quizlet

Start studying selenium. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

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