Abstract: The objective of the present invention is to provide: a spherical magnesium oxide which has high sphericity and excellent moisture resistance, and has excellent fluidity by which a resin composition exhibits excellent fluidity when filled in a resin; and a method for producing the same. The present invention is a spherical magnesium oxide characterized in that: 10-2000 ppm of boron is contained; the total content of silicon and phosphorus is 300-4000 ppm; and the sphericity that can be read from the SEM photograph is 1.00-1.10, when the volume-based cumulative 50% particle diameter (D50) measured by means of a laser diffraction scattering particle size distribution measurement, is in the range of 3-200 ?m.

Abstract: The objective of the present invention is to provide: a spherical magnesium oxide which has high sphericity and excellent moisture resistance, and has excellent fluidity by which a resin composition exhibits excellent fluidity when filled in a resin; and a method for producing the same. The present invention is a spherical magnesium oxide characterized in that: 10-2000 ppm of boron is contained; the total content of silicon and phosphorus is 300-4000 ppm; and the sphericity that can be read from the SEM photograph is 1.00-1.10, when the volume-based cumulative 50% particle diameter (D50) measured by means of a laser diffraction scattering particle size distribution measurement, is in the range of 3-200 ?m.

Abstract: A magnesium oxide powder includes a magnesium oxide particle, wherein the number of an open pore communicating with a surface of the magnesium oxide particle measured by a specific measurement method is 8.0×10?4/?m2 or less.

Abstract: A magnesium oxide powder, including a specific magnesium oxide particle, can suppress an increase in viscosity when a resin is filled therewith and can realize high thermal conduction of a resin composition including the resin, and a filler composition, a resin composition, and a heat dissipation part including the magnesium oxide powder. The magnesium oxide powder includes a magnesium oxide particle, wherein an oil absorption of the magnesium oxide particle in the case of linseed oil measured according to JIS K 5101-13-1 is 2.5 mL/10 g or less.

Abstract: A magnesium oxide powder containing magnesium oxide particles, wherein an average sphericity of a magnesium oxide particle having a projected area equivalent circle diameter of a particle cross section by microscopy of 10 ?m or more among the magnesium oxide particles is 0.73 or more and 0.95 or less, a proportion of a magnesium oxide particle having a sphericity of 0.65 or less among the magnesium oxide particles is 20% or less on a number basis, and a proportion of a magnesium oxide particle having a sphericity of 0.55 or less among the magnesium oxide particles is 15% or less on a number basis.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree RBlaine/RBET of 3.0 to 5.5 wherein RBlaine is the particle size calculated from the Blaine specific surface area and RBET is the particle size calculated from the BET specific surface area.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×103 to 25.0×103 m2·kg?1 and a Blaine specific surface area of 2.0×103 to 7.0×103 m2·kg?1.

Abstract: Provided are: a spherical magnesium oxide having not only high sphericity but also smooth surface and having excellent moisture resistance and excellent filling properties, and a method producing the same. In the present invention, by controlling the boron and iron contents of the calcined magnesium oxide to be in the respective predetermined ranges, there is provided a spherical magnesium oxide having a volume-based cumulative 50% particle diameter (D50), as measured by a laser diffraction/scattering particle size distribution measurement, in the range of from 3 to 200 ?m, which is the range for a relatively large particle diameter, and a high sphericity of 1.00 to 1.20, as measured from viewing a SEM photomicrograph, as well as smooth surface, and having excellent moisture resistance and excellent filling properties. A predetermined spherical magnesium oxide is provided by virtue of the synergies obtained from the boron content of 300 to 2,000 ppm and the iron content of 100 to 1,500 ppm.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a Blaine specific surface area of 2.5×103 to 7.0×103 m2·kg?1 and CAA of 50 to 170 seconds.

Abstract: Provided is a magnesium oxide-containing spinel powder capable of producing a ceramic sintered body having high strength and excellent strength stability. In the magnesium oxide-containing spinel powder, a 50% particle diameter (D50) is 0.30 to 10.00 ?m, a ratio (D90-D50)/(D50-D10) of a difference between a 90% particle diameter (D90) and the 50% particle diameter (D50) and a difference between the 50% particle diameter (D50) and a 10% particle diameter (D10) is 1.0 to 5.0, and a composition ratio of Mg and Al in terms of an oxide equivalent content is 50 to 90% by weight of MgO and 10 to 50% by weight of Al2O3.

Abstract: Provided is a magnesium oxide-containing spinel powder capable of producing a ceramic sintered body having high strength and excellent strength stability. In the magnesium oxide-containing spinel powder, a 50% particle diameter (D50) is 0.30 to 10.00 ?m, a ratio (D90-D50)/(D50-D10) of a difference between a 90% particle diameter (D90) and the 50% particle diameter (D50) and a difference between the 50% particle diameter (D50) and a 10% particle diameter (D10) is 1.0 to 5.0, and a composition ratio of Mg and Al in terms of an oxide equivalent content is 50 to 90% by weight of MgO and 10 to 50% by weight of Al2O3.

Abstract: A magnesium oxide powder having excellent dispersibility and a small average particle diameter as well as a uniform particle diameter and containing no very small size particles is obtained. A magnesium oxide powder which is particles, wherein the magnesium oxide powder has a BET specific surface area of 5 m2/g or more, a cumulative 50% particle diameter (D50) obtained in the measurement of laser diffraction scattering particle size distribution of 0.3 to 1.5 ?m, a ratio of a cumulative 90% particle diameter (D90) to a cumulative 10% particle diameter (D10) (D90/D10) obtained in the measurement of laser diffraction scattering particle size distribution of 5 or less, and a D10 of 0.1 ?m or more.

Abstract: A magnesium oxide powder having excellent dispersibility and a small average particle diameter as well as a uniform particle diameter and containing no very small size particles is obtained. A magnesium oxide powder which is particles, wherein the magnesium oxide powder has a BET specific surface area of 5 m2/g or more, a cumulative 50% particle diameter (D50) obtained in the measurement of laser diffraction scattering particle size distribution of 0.3 to 1.5 ?m, a ratio of a cumulative 90% particle diameter (D90) to a cumulative 10% particle diameter (D10) (D90/D10) obtained in the measurement of laser diffraction scattering particle size distribution of 5 or less, and a D10 of 0.1 ?m or more.

Abstract: Disclosed herein are a sintered magnesium oxide material which is capable of suppressing the occurrence of splashing during film formation and which is less likely to cause clogging of a supply inlet of a film formation device, a deposition material for PDP-protecting film using the same, and a process for producing the sintered material. The sintered magnesium oxide material contains magnesium oxide, 3 to 50 mass % of an oxide of a Group 2A element other than magnesium in the periodic table, and if necessary, 1000 ppm or less of one or two or more elements selected from the group consisting of aluminum, yttrium, cerium, zirconium, scandium, and chromium, and has a disk-like, elliptical plate-like, polygonal plate-like, or half-moon-like shape or a cubic or rectangular solid shape with rounded apexes.

Abstract: The object is to provide a high-purity magnesium oxide particle aggregate that is redispersible and can be supplied with keeping high purity, and a method for producing the same. A magnesium oxide particle aggregate that is an aggregate of magnesium oxide particles, wherein the magnesium oxide particles have an average particle size of 1 ?m or less, and comprises Si, Al, Ca, Fe, V, Cr, Mn, Ni, Zr, B and Zn as impurities in their respective amounts of 10 ppm by mass or less, wherein the total amount of the impurities is 100 ppm by mass or less.

Abstract: Magnesium oxide powders having a large diameter of crystallite, and having a favorable crystallinity are provided. Magnesium oxide powders: having peak widths at half-height of the peaks on a (111) plane, a (200) plane and a (220) plane of each no greater than 0.20 degrees as determined with a powder X-ray diffraction method carried out using a Cu—K? ray; and having a crystallite diameter of no less than 700 ?.

Abstract: A magnesium oxide powder having excellent dispersibility and a small average particle diameter as well as a uniform particle diameter and containing no very small size particles is obtained. A magnesium oxide powder which is particles, wherein the magnesium oxide powder has a BET specific surface area of 5 m2/g or more, a cumulative 50% particle diameter (D50) obtained in the measurement of laser diffraction scattering particle size distribution of 0.3 to 1.5 ?m, a ratio of a cumulative 90% particle diameter (D90) to a cumulative 10% particle diameter (D10) (D90/D10) obtained in the measurement of laser diffraction scattering particle size distribution of 5 or less, and a D10 of 0.1 ?m or more.

Abstract: Magnesium oxide powders having a large diameter of crystallite, and having a favorable crystallinity are provided. Magnesium oxide powders: having peak widths at half-height of the peaks on a (111) plane, a (200) plane and a (220) plane of each no greater than 0.20 degrees as determined with a powder X-ray diffraction method carried out using a Cu—K? ray; and having a crystallite diameter of no less than 700 ?.

Abstract: The object is to provide a high-purity magnesium oxide particle aggregate that is redispersible and can be supplied with keeping high purity, and a method for producing the same. A magnesium oxide particle aggregate that is an aggregate of magnesium oxide particles, wherein the magnesium oxide particles have an average particle size of 1 ?m or less, and comprises Si, Al, Ca, Fe, V, Cr, Mn, Ni, Zr, B and Zn as impurities in their respective amounts of 10 ppm by mass or less, wherein the total amount of the impurities is 100 ppm by mass or less.

Abstract: Provided is a MgO single crystal for obtaining a magnesium oxide (MgO) single crystal deposition material which is prevented from splashing during the vapor deposition in, e.g., an electron beam deposition method without reducing the deposition rate, and for obtaining a MgO single crystal substrate which can form thereon, e.g., a superconductor thin film having excellent superconducting properties. A MgO single crystal having a calcium content of 150×10?6 to 1,000×10?6 kg/kg and a silicon content of 10×10?6 kg/kg or less, wherein the MgO single crystal has a variation of 30% or less in terms of a CV value in detected amounts of calcium fragment ions, as analyzed by TOF-SIMS with respect to the polished surface of the MgO single crystal. A MgO single crystal deposition material and a MgO single crystal substrate for forming a thin film obtained from the MgO single crystal.