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.

Abstract: A magnesium oxide single crystal having controlled crystallinity has a subboundary, and ranges of variation of diffraction line positions, as measured for reciprocal lattice maps with respect to a region surrounded by the same subboundary, with the range of the variation of 1×10?3 to 2×10?2 degree of on ?? coordinates, and with the range of the variation of 4×10?4 to 5×10?3 degree on 2? coordinates.

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.

Abstract: A phosphorus-containing coated magnesium oxide powdered material comprising a coated magnesium oxide powdered material having a surface coating layer comprised of a double oxide, wherein the phosphorus-containing coated magnesium oxide powdered material has a coating layer comprised of a magnesium phosphate compound in at least part of a surface of the coated magnesium oxide powdered material, wherein the content of the magnesium phosphate compound in the coated magnesium oxide powdered material is 0.1 to 10% by mass, in terms of phosphorus; a method for producing a phosphorus-containing coated magnesium oxide powdered material, wherein the method comprises treating a coated magnesium oxide powdered material having a surface coating layer comprised of a double oxide with a phosphorus compound, and then calcining the resultant powdered material at 300° C.

Abstract: A magnesium oxide single crystal having controlled crystallinity comprising a subboundary, and ranges of variation of diffraction line positions, as measured for reciprocal lattice maps with respect to a region surrounded by the same subboundary, with the range of the variation of 1×10?3 to 2×10?2 degree of on ?? coordinates, and with the range of the variation of 4×10?4 to 5×10?3 degree on 2? coordinates.

Abstract: A phosphorus-containing coated magnesium oxide powdered material comprising a coated magnesium oxide powdered material having a surface coating layer comprised of a double oxide, wherein the phosphorus-containing coated magnesium oxide powdered material has a coating layer comprised of a magnesium phosphate compound in at least part of a surface of the coated magnesium oxide powdered material, wherein the content of the magnesium phosphate compound in the coated magnesium oxide powdered material is 0.1 to 10% by mass, in terms of phosphorus; a method for producing a phosphorus-containing coated magnesium oxide powdered material, wherein the method comprises treating a coated magnesium oxide powdered material having a surface coating layer comprised of a double oxide with a phosphorus compound, and then calcining the resultant powdered material at 300° C.

Abstract: Provided is a sphere-shaped coated magnesium oxide powder having a surface coated with a double oxide and having an average shape factor of 1.25 or less, wherein the powder is advantageous not only in that it has excellent humidity resistance, but also in that it has excellent filling property and excellent flowability when being used as filler for a resin. In addition, provided is a method for producing a sphere-shaped coated magnesium oxide powder, wherein the method comprises allowing a compound of an element forming a double oxide to be present on the surface of magnesium oxide powder, and then fusing the resultant magnesium oxide powder at a high temperature so that the surface of the magnesium oxide powder is coated with the double oxide and the magnesium oxide powder is shaped into sphere. Further, provided are a resin composition comprising the sphere-shaped coated magnesium oxide powder and an electronic device using the resin composition.