Abstract: A metal container to be filled with a halogen containing gas, with the inner surface processed with a polishing agent. The gas has a reduced purity decline by the increase of the water content or impurities from the inner surface of the container which is absorbed by the gas over the passage of time. The inner surface processing method is improved such that the value of dividing the area of the Si2s peak by the area of the Fe2p3/2 peak in the X-ray photoelectron spectrum of the gas container inner surface with the inner surface process with a polishing agent applied is 0.3 or less.

Abstract: A metal container to be filled with a halogen containing gas, with the inner surface processed with a polishing agent. The gas has a reduced purity decline by the increase of the water content or impurities from the inner surface of the container which is absorbed by the gas over the passage of time. The inner surface processing method is improved such that the value of dividing the area of the Si2s peak by the area of the Fe2p3/2 peak in the X-ray photoelectron spectrum of the gas container inner surface with the inner surface process with a polishing agent applied is 0.3 or less.

Abstract: An electrode for electrolyzing an electrolyte comprising an ammonium fluoride (NH4F)-hydrogen fluoride (HF)-containing molten salt and having a composition ratio (HF/NH4F) of 1 to 3 to prepare a nitrogen trifluoride (NF3) gas and an electrolyte for use in the preparation of NF3 gas, and a preparation method of the NF3 gas by the use of the electrode and the electrolyte. The electrode comprises nickel having 0.07 wt % or less of Si content and containing a transition metal other than nickel. The electrolyte also contains a transition metal other than nickel.

Abstract: A process for producing high-purity nitrogen trifluoride gas by molten salt electrolysis using a nickel electrode and ammonium hydrogenfluoride as an electrolyte, wherein carbon element constituting impurity gases entrained in a crude gas, among impurities in the nickel electrode as an anode is controlled to an amount of 400 wt ppm or less. The process allows high-purity nitrogen trifluoride gas to be produced with a purity of 4N or higher.

Abstract: An electrode for electrolyzing an electrolyte comprising an ammonium fluoride (NH4F)-hydrogen fluoride (HF)-containing molten salt and having a composition ratio (HF/NH4F) of 1 to 3 to prepare a nitrogen trifluoride (NF3) gas and an electrolyte for use in the preparation of NF3 gas, and a preparation method of the NF3 gas by the use of the electrode and the electrolyte. The electrode comprises nickel having 0.07 wt % or less of Si content and containing a transition metal other than nickel. The electrolyte also contains a transition metal other than nickel.

Abstract: The method for preparing a gaseous metallic floride is here disclosed which comprises reacting a metal or its oxide with a fluorine gas or nitrogen trifluoride gas, the aforesaid method being characterized by comprising the steps of mixing the metal or its oxide with a molding auxiliary comprising a solid metallic fluoride which does not react with fluorine and nitrogen trifluoride; molding the resulting mixture under pressure; and contacting the molded pieces with the fluorine gas or nitrogen trifluoride gas, while the molded pieces are heated.