Abstract: In the production process of the present invention for high purity polycrystal silicon, using a vertical reactor having a silicon chloride gas-feeding nozzle and a reducing agent gas-feeding nozzle which are disposed at an upper part and a waste gas discharge pipe, a silicon chloride gas and a reducing agent gas are fed into the reactor to form polycrystal silicon at a tip part of the silicon chloride gas-feeding nozzle by the reaction of the silicon chloride gas with the reducing agent gas, and the polycrystal silicon is allowed to grow from the tip part of the silicon chloride gas-feeding nozzle toward a lower part thereof.

Abstract: In the production process of the present invention for high purity polycrystal silicon, using a vertical reactor having a silicon chloride gas-feeding nozzle and a reducing agent gas-feeding nozzle which are disposed at an upper part and a waste gas discharge pipe, a silicon chloride gas and a reducing agent gas are fed into the reactor to form polycrystal silicon at a tip part of the silicon chloride gas-feeding nozzle by the reaction of the silicon chloride gas with the reducing agent gas, and the polycrystal silicon is allowed to grow from the tip part of the silicon chloride gas-feeding nozzle toward a lower part thereof.

Abstract: In the production process of the present invention for high purity polycrystal silicon, using a vertical reactor having a silicon chloride gas-feeding nozzle and a reducing agent gas-feeding nozzle which are disposed at an upper part and a waste gas discharge pipe, a silicon chloride gas and a reducing agent gas are fed into the reactor to form polycrystal silicon at a tip part of the silicon chloride gas-feeding nozzle by the reaction of the silicon chloride gas with the reducing agent gas, and the polycrystal silicon is allowed to grow from the tip part of the silicon chloride gas-feeding nozzle toward a lower part thereof.

Abstract: In the production process of the present invention for high purity polycrystal silicon, using a vertical reactor having a silicon chloride gas-feeding nozzle and a reducing agent gas-feeding nozzle which are disposed at an upper part and a waste gas discharge pipe, a silicon chloride gas and a reducing agent gas are fed into the reactor to form polycrystal silicon at a tip part of the silicon chloride gas-feeding nozzle by the reaction of the silicon chloride gas with the reducing agent gas, and the polycrystal silicon is allowed to grow from the tip part of the silicon chloride gas-feeding nozzle toward a lower part thereof.

Abstract: Silica glass powders are prepared by mixing a silicic acid ester, water in an amount equal and or larger than 0.5 gram equivalent of an alkoxy group of the silicic acid ester and siliceous particles and dispersing the siliceous particles which have particle sizes larger than 400 .mu.m in an amount of less than 10% by weight and particle sizes of less than 20 .mu.m in an amount of less than 50% by weight and which are dispersed in an amount equal to or larger than 10% by weight of the weight of silica prepared by roasting the silicic acid ester in the same amount as used for the preparation of the mixture, gelling the dispersion to give a gel, drying the gel, and sintering the dried gel. The silica glass powders of high purity are suitable for various uses such as raw materials for the silica glass products for semiconductor industry and for multicomponent glass for optical communication.