GB838378A - An improved process for the production of metals and other chemical elements of metallic character in a state of high purity - Google Patents

Abstract

<PICT:0838378/III/1> Non-metallic elements in a high state of purity, especially those belonging to Group IV, V and VI of the Periodic System, are prepared by passing a gaseous mixture of a volatile compound of the element and a volatile reducing agent, under reduced pressure, through a reaction chamber in which it is subjected, without the use of electrodes, to a high-frequency alternating electric field which induces electric discharges in the mixture and initiates chemical reduction at the ambient or at a moderately elevated temperature. One example quoted describes the production of silicon using the apparatus shown in which a gaseous mixture of silicon tetrachloride and hydrogen is fed from the container 1 at a pressure of 2 cm. of mercury through line 2 fitted with cocks 6 and 7 to the vessel 3 of 200 c.c. volume evacuated by pump 10. The reaction vessel 3 having a diameter of 10 cm. has a coil 4 of ten turns wound on the outside and a high-frequency continuous wave current produced by a 5 kw. generator at a frequency of 1 megacycle per second is passed through the coil to induce the electric discharge in the mixture. Silicon, formed by the reduction of the tetrachloride accumulates in the detachable bottom 3a of the reaction vessel and is removed. Other volatile silicon compounds which may be reduced include SiHCl3, SiH2Cl2, SiH3Cl or the corresponding compounds with the other halogens. A modification of the process discloses the use of ultra-high-frequencies delivered either as sustained waves or as pulse discharges by means of wave-guides.