Abstract: In spherical silica powder according to an embodiment of the present invention, an NO3? content obtained based on an ion chromatography method is less than or equal to 5 ppm.

Abstract: A method for producing a packaging body of the present invention includes a production step of producing a metal oxide powder, and a sealing step of placing the metal oxide powder in a bag that is filled with at least one gas selected from the group consisting of a noble gas, nitrogen gas, oxygen gas, and dry air, followed by sealing the bag, the metal oxide powder being a silica powder or a magnesia powder, the bag having a moisture permeability as measured according to JIS Z 0222-1959 of 0.30 g/(m2·day) or less.

Abstract: A metal oxide powder in which the metal is other than uranium, iron and titanium, and, in the metal oxide powder, the content rate of uranium is 1.0 ppb by mass or less, the content rate of iron is 100 ppm by mass or less in terms of Fe2O3, the content rate of titanium in terms of TiO2 oxide is 8 ppm by mass or less. Included is a method of producing a metal oxide powder which removes impurities from a metal oxide powder so that a metal oxide powder having a high purity can be obtained, and a metal oxide powder produced according to the method.

Abstract: A silicon dioxide powder has a uranium content of 0.8 ppb by mass or less and a sphericity of 0.80 or more. The silicon dioxide powder has a low uranium content and a high sphericity.

Abstract: Silica powder having a dielectric loss tangent of 0.004 or less, in which the number of silicon metal particles in 10 g of the silica powder is 30 or less. A method for producing silica powder, including a heating step of heating silica powder in the presence of chlorine. Silica powder having a low dielectric loss tangent and a low silicon metal content, and a method for producing the silica powder can be provided.

Abstract: One aspect of the present disclosure provides a boron nitride powder containing agglomerated particles formed by agglomeration of primary particles of hexagonal boron nitride, in which a degree of purity is 98.5% by mass or more, and a number of particles containing carbon is 10 or less per 10 g of the boron nitride powder.

Abstract: One aspect of the present disclosure provides a boron nitride powder containing agglomerated particles formed by agglomeration of primary particles of hexagonal boron nitride, in which a degree of purity is 98.5% by mass or more, and a concentration of elutable impurities is 700 ppm or less.

Abstract: One aspect of the present disclosure provides a boron nitride powder containing agglomerated particles formed by agglomeration of primary particles of hexagonal boron nitride, in which a degree of purity is 98.5% by mass or more, and a number of particles having a magnetizing ability is 10 or less per 10 g of the boron nitride powder.