Search results
Results from the WOW.Com Content Network
The minimum distance between chains is 343.6 pm. Gray selenium is formed by mild heating of other allotropes, by slow cooling of molten selenium, or by condensing selenium vapor just below the melting point. Whereas other selenium forms are insulators, gray selenium is a semiconductor showing appreciable photoconductivity.
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Spectral lines of selenium: Other properties; ... phase comment = | melting point K = | melting point C = | melting point F = | melting point ref = | melting point ...
Selenium dioxide is the chemical compound with the formula SeO 2. This colorless solid is one of the most frequently encountered compounds of selenium . It is used in making specialized glasses as well as a reagent in organic chemistry.
A stoichiometric mixture of elemental bismuth and selenium, when heated above the melting points of these elements in the absence of air, will become a liquid that freezes to crystalline Bi 2 Se 3. [27] Large single crystals of bismuth selenide can be prepared by the Bridgman–Stockbarger method. [28]
Tin(II) selenide can be formed by combining the elements tin and selenium above 350 °C. [13] Problems with the composition are encountered during synthesis. Two phases exist—the hexagonal SnSe 2 phase and the orthorhombic SnSe phase. Specific nanostructures can be synthesized, [14] but few 2D nanostructures have been prepared. Both square ...
Hydrogen selenide is hazardous, being the most toxic selenium compound [3] and far more toxic than its congener hydrogen sulfide. The threshold limit value is 0.05 ppm. The gas acts as an irritant at concentrations higher than 0.3 ppm, which is the main warning sign of exposure; below 1 ppm, this is "insufficient to prevent exposure", while at ...
Tungsten diselenide is an inorganic compound with the formula WSe 2. [6] The compound adopts a hexagonal crystalline structure similar to molybdenum disulfide.The tungsten atoms are covalently bonded to six selenium ligands in a trigonal prismatic coordination sphere while each selenium is bonded to three tungsten atoms in a pyramidal geometry.