| 释义 |
selenium Chem.|sɪˈliːnɪəm|
[mod.L., f. Gr. σελήν-η moon: see -ium. Cf. G. selen.
Named in 1818 by Berzelius, the discoverer (Journal für Chemie u. Physik XXIII. 316), who explains that the name was chosen to indicate the resemblance of the properties of the new element to those of tellurium.]
a. One of the rarer elements, closely resembling tellurium in properties, and, like that element, formerly classed among the metals, but now regarded as non-metallic. Symbol Se; atomic weight 79.
Like sulphur, to which it is in many respects analogous, it has several allotropic forms; one of these, still sometimes known as metallic selenium, is a dark grey or black solid with metallic lustre.
An important property of selenium is that its electrical resistance is greatly decreased by exposure to light: hence its use in the photophone or radiophone of A. Graham Bell.
1818tr. Berzelius in Ann. Philos. XI. 292 The analogy of tellurium has induced me to give it the name of selenium. 1826Henry Elem. Chem. I. 464 Phosphuret of Selenium. 1849D. Campbell Inorg. Chem. 61 Selenium when distilled is of a reddish-brown colour, when reduced to powder it is red; when fused in a mass, it is of a lead grey colour and metallic lustre. 1881A. G. Bell Sound by Radiant Energy 23 But the selenium was very inconstant in its action.
b. attrib. as selenium cell, a photoconductive or photovoltaic cell containing selenium; selenium eye (see quot. 1893).
1880A. G. Bell in Jrnl. Franklin Inst. Oct. 243 The resistance of selenium cells employed by former experimenters was measured in millions of ohms. 1893Sloane Stand. Electr. Dict., Selenium eye, a model eye in which selenium in circuit with a battery and galvanometer takes the place of the retina of the human eye. 1929[see photoconductive a.]. 1946Nature 20 July 88/1 In the early days of his training he [sc. J. L. Baird] devised an improved pattern of selenium cell, which led him to develop a crude form of television. 1977J. Hedgecoe Photographer's Handbk. 32 Your meter may use a selenium cell which generates a minute current of electricity, measured on a galvanometer. |