Abstract: A process for production of polysilicon and silicon tetrachloride is provided in which a raw material that is supplied stably and is available at low cost can be used, chlorination reaction can be smoothly promoted, impurities generated after chlorination reaction can be controlled, and production efficiency is superior in a polysilicon producing step. The process includes a step of chlorination in which a granulated body consisting of silicon dioxide and carbon-containing material is chlorinated to generate silicon tetrachloride, a step of reduction in which silicon tetrachloride is reduced by a reducing metal to generate polysilicon, and a step of electrolysis in which chloride of the reducing metal by-produced in the reduction step is molten salt-electrolyzed to generate the reducing metal and chlorine gas.

Abstract: A metallic nickel powder exhibits superior oxidation behavior and sintering behavior in a process for production of a multilayer ceramic capacitor, and as a result, can prevent delamination, a process for production of the metallic powder is provided. The metallic nickel powder is treated with a carbonic acid water solution. The metallic nickel powder has an average particle diameter of not more than 1.0 ?m, oxygen content in a range of from 0.3 to 2.0 wt %, and oxide layer having a thickness in a range of from 2 to 10 nm over the entire surface. In the process for production of the metallic nickel powder, the powder is treated with a carbonic acid water solution and is heated in an oxidizing atmosphere.

Abstract: A metallic nickel powder exhibits superior oxidation behavior and sintering behavior in a process for production of a multilayer ceramic capacitor, and as a result, can prevent delamination, a process for production of the metallic powder is provided. The metallic nickel powder is treated with a carbonic acid water solution. The metallic nickel powder has an average particle diameter of not more than 1.0 ?m, oxygen content in a range of from 0.3 to 2.0 wt %, and oxide layer having a thickness in a range of from 2 to 10 nm over the entire surface. In the process for production of the metallic nickel powder, the powder is treated with a carbonic acid water solution and is heated in an oxidizing atmosphere.

Abstract: Raw metal is intermittently and continuously charged into a chlorination furnace, the raw metal and chlorine gas are reacted in the chlorination furnace to continuously generate metal chloride vapor, and the metal chloride vapor and hydrogen gas are reacted in a reduction furnace to continuously obtain metallic powder. Furthermore, the chlorination furnace in which the chlorination reaction is proceeding is weighed, and the charged amount of the raw metal to the chlorination furnace is controlled depending on the weighing result.

Abstract: Metal chloride vapor and reducing gas are brought into contact to form metallic powder, the metallic powder is washed in carbonic acid aqueous solution, and the metallic powder is classified in a liquid phase. In this way, metallic powder, such as nickel powder, in which the content of chloride components is extremely small and the coarse particle content is small, can be efficiently produced.

Abstract: Metal chloride vapor and reducing gas are brought into contact to form metallic powder, the metallic powder is washed in carbonic acid aqueous solution, and the metallic powder is classified in a liquid phase. In this way, metallic powder, such as nickel powder, in which the content of chloride components is extremely small and the coarse particle content is small, can be efficiently produced.

Abstract: A process for production of metallic powder comprising contacting a metallic chloride gas with a reductive gas in a temperature range for a reducing reaction to form a metallic powder and subsequently contacting the metallic powder with an inert gas such as nitrogen gas to cool the powder, wherein the rate of cooling is 30° C. or more for temperatures from the temperature range for the reducing reaction to a temperature of 800°C. or less. The metallic powder is rapidly cooled, which results in suppression of agglomeration of particles in the metallic powder and the growth of secondary particles. Growth of particles of a metallic powder formed in a reduction process into secondary particles through agglomeration after the reduction process is suppressed, and a ultrafine metallic powder having a particle diameter of, for example, 1&mgr;m or less, can be reliably produced.

Abstract: A process for production of a barium titanate powder, the process comprises adding an aqueous solution of a titanium compound and an aqueous solution of a barium compound and an alkali metal hydroxide into an alkaline solution under stirring, thereby contacting the aqueous solutions with each other while controlling the molar ratio of the titanium compound to the barium compound to be within the range of 0.8 to 1.2.

Abstract: A barium titanate powder has an average particle size ranging from 0.1-1.0 &mgr;m, a CV value (standard deviation of the particle size/the average particle size) of the particle size distribution being 40% or less, and a zeta-potential ranging from −30 to −60 mV measured by a laser Doppler method using electrophoresis at pH 6.4. The barium titanate powder is presintered at a temperature ranging from 900 to 1200° C. The barium titanate powder has superior dispersion characteristics in slurrying, and is capable of partly inhibiting agglomeration of the barium titanate after sintering. It is therefore suitable as materials for dielectric layers of multilayer ceramic capacitors. In particular, the barium titanate has a sintered density of 95% or more of the theoretical density thereof, and the dielectric constant is 4000 or more.

Abstract: Chlorine gas from a supply nozzle is mixed with the vapor of nickel chloride and the mixed gas is supplied from a supply nozzle into a hydrogen gas atmosphere in a reduction reactor at a reduction temperature of 900 to 1100° C. The volume of chlorine gas to be mixed versus the vapor of nickel chloride is adjusted to a ratio of 0.01 to 0.5 moles per mole of the vapor of nickel chloride. The particle size of the nickel powder can be controlled appropriately, and also, uniformity of particle size, smoothability of surfaces of particles, and sphericity can be improved.

Abstract: A process for producing metallic powders a chlorination step for continuously producing chloride gas of metal by reacting metal with chlorine gas, and a reduction step for continuously reducing the metallic chloride gas by reacting the metallic chloride gas produced in the chlorination step with reducing gas. Regulating the feed rate of the chlorine gas can control the feed rate of the metallic chloride gas, whereby the particle diameters of produced metal powders can be stably controlled. Thus, the invention can make the particle diameters stable and arbitrarily control the diameters in the range of 0.1 to 1.0 &mgr;m.