Abstract: A silica particle in which, in an image obtained by taking a scanning transmission electron image in a bright field mode using an ultra-high resolution electron microscope, a ratio of an area of a white portion within the silica particle to a total area of the silica particle is 2% to 12%. The ratio of the area of the white portion within the silica particle to the total area of the silica particle may be 7% to 10%.

Abstract: An object of the present invention is to provide a silica particle having excellent polishing characteristics and storage stability, a method for producing the silica particle, a silica sol containing the silica particles, and a polishing composition containing the silica sol. Another object of the present invention is to provide a polishing method, a method for producing a semiconductor wafer, and a method for producing a semiconductor device, which are excellent in productivity of an object to be polished. The silica particle in the present invention satisfies formula (1): y?4.2 where a d value measured by wide-angle X-ray scattering is y ?.

Abstract: An object of the present invention is to provide a silica particle having excellent polishing characteristics and storage stability. The present invention relates to a silica particle in which a proportion of silanol groups present on a surface represented by (x/y)×100% is 15% or less, where a content of silanol groups on the surface is x mass % and a content of bulk silanol groups is y mass %.

Abstract: An object of the present invention is to provide a silica particle having excellent polishing characteristics and storage stability, a method for producing the silica particle, a silica sol containing the silica particles, and a polishing composition containing the silica sol. Another object of the present invention is to provide a polishing method, a method for producing a semiconductor wafer, and a method for producing a semiconductor device, which are excellent in productivity of an object to be polished. The silica particle in the present invention satisfies formula (1): y?4.2 where a d value measured by wide-angle X-ray scattering is y ?.

Abstract: Provided are: a dehydration system in which occurrence of damage to a membrane element in a zeolite membrane module can be suppressed; and an operation method of the same. This dehydration system for aqueous organic compounds includes: a zeolite membrane module, inside of which one or plural tubular membrane elements each having a zeolite membrane are arranged and which separates water from an aqueous organic compound supplied thereto; a pressure-reducing means; a condenser, and the dehydration system has at least one of the following configurations (1) and (2). Configuration (1): the dehydration system includes a temperature-maintaining means for maintaining a pipe connecting the membrane module and the condenser to have a temperature at which water does not condense, and Configuration (2): the pipe connecting the membrane module and the condenser is arranged downward from a permeated water outlet of the membrane module toward the condenser.