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 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: The present invention is related to a magnesium oxide particle aggregate with the requirement of a first inflection point diameter is more than 0.30×10?6 to 0.60×10?6 m, a particle void volume is 0.50×10?3 to 0.90×10?3 m3·kg?1, and a micropore volume is 0.04×10?3 to 0.11×10?3 m3·kg?1 in the cumulative intrusion volume curve of said particle by having controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled.

Abstract: An object of the present invention is to provide a magnesium oxide particle aggregate having a controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled. The object can be achieved by a magnesium oxide particle aggregate characterized in that a first inflection point diameter is 0.30×10−6 m or less, an interparticle void volume is 1.40×10−3 to 2.20×10−3 m3/kg and a particle void volume is 0.55×10−3 to 0.80×10−3 m3/kg in a cumulative intrusion volume curve of the particle aggregate.

Abstract: The present invention is related to a magnesium oxide particle aggregate with the requirement of a first inflection point diameter is more than 0.30×10−6 to 0.60×10−6 m, a particle void volume is 0.50×10−3 to 0.90×10−3 m3·kg−1, and a micropore volume is 0.04×10−3 to 0.11×10−3 m3·kg−1 in the cumulative intrusion volume curve of said particle by having controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled.

Abstract: An object of the present invention is to provide a magnesium oxide particle aggregate having a controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled. The object can be achieved by a magnesium oxide particle aggregate characterized in that a first inflection point diameter is 0.30×10−6 m or less, an interparticle void volume is 1.40×10−3 to 2.20×10−3 m3/kg and a particle void volume is 0.55×10−3 to 0.80×10−3 m3/kg in a cumulative intrusion volume curve of the particle aggregate.