Abstract: Provided is a method for producing SiC single crystal substrate including placing a SiC single crystal serving as a seed crystal and a SiC powder layer in a container in a state in which the SiC single crystal and the SiC powder layer are in contact with each other and performing a heat treatment by placing the container in an effective working zone of a firing furnace controlled to a temperature range within ±50° C. of a preset temperature to grow a SiC single crystal on the seed crystal.

Abstract: A rare earth-containing SiC substrate includes a rare earth element and Al. A concentration of the rare earth element is from 1×1016 atoms/cm3 to 1×1019 atoms/cm3 inclusive and a concentration of Al is from 1×1016 atoms/cm3 to 1×1021 atoms/cm3 inclusive.

Abstract: A biaxially oriented SiC composite substrate includes a first biaxially oriented SiC layer that contains a threading screw dislocation and a basal plane dislocation, and a second biaxially oriented SiC layer that is formed continuously from the first biaxially oriented SiC layer and that contains 1×1016 atoms/cm3 or more and 1×1019 atoms/cm3 or less of a rare earth element. The defect density of a surface of the second biaxially oriented SiC layer is smaller than the defect density of the first biaxially oriented SiC layer.

Abstract: Provided is a SiC composite substrate including a biaxially-oriented SiC layer in which SiC is oriented in both a c-axis direction and an a-axis direction, and a SiC polycrystalline layer provided on one surface of the biaxially-oriented SiC layer. A joint interface of the biaxially-oriented SiC layer and the SiC polycrystalline layer has an uneven shape, which has an amount of unevenness of 1 to 200 ?m.

Abstract: Provided is a SiC composite substrate including a biaxially-oriented SiC layer in which SiC is oriented in both a c-axis direction and an a-axis direction, and a SiC polycrystalline layer provided on one surface of the biaxially-oriented SiC layer. Pores are present in the SiC composite substrate.

Abstract: A SiC composite substrate includes a SiC single crystal layer and at least one biaxially oriented SiC layer. The at least one biaxially oriented SiC layer is disposed on the SiC single crystal. In the biaxially oriented SiC layer, the SiC is oriented in both a c-axis direction and an a-axis direction. The biaxially oriented SiC layer has pores and has a density of defect reaching the surface of 1.0×101/cm2 or less.

Abstract: A method for producing a transparent alumina sintered body according to the present invention includes (a) a step of preparing an alumina raw material powder containing a plate-like alumina powder having an aspect ratio of 3 or more and a fine alumina powder having an average particle diameter smaller than that of the plate-like alumina powder so that, when a mixing ratio of the plate-like alumina powder to the fine alumina powder in terms of mass ratio is assumed to be T:(100?T), T is 0.001 or more and less than 1, and so that a mass ratio R1 of F relative to Al in the alumina raw material powder is less than 15 ppm; (b) a step of forming a raw material for forming containing the alumina raw material powder into a compact; and (c) a step of sintering the compact so as to obtain a transparent alumina sintered body.

Abstract: An oriented ceramic sintered body production method includes (a) a step of preparing a ceramic compact before firing into an oriented ceramic sintered body; and (b) a step of obtaining an oriented ceramic sintered body by sandwiching the ceramic compact between a pair of releasing sheets, placing the ceramic compact and the releasing sheets in a hot press firing furnace, and hot press firing the ceramic compact while applying a pressure by a pair of punches through the pair of releasing sheets, wherein each of the releasing sheets is a releasing sheet such that, after the releasing sheet is sandwiched between PET films, is then placed and vacuum-packed on a stainless steel sheet, and is isostatically pressed at 200 kg/cm2, a surface of the releasing sheet on the side opposite from the stainless steel sheet has a profile curve with a maximum profile height Pt of 0.8 ?m or less.

Abstract: An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 1° or more and 3° or less and an average sintered grain size of 20 ?m or more.

Abstract: An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 0.1° or more and less than 1.0° and an average sintered grain size of 10 ?m or more.

Abstract: An alumina sintered body of the present invention has a degree of c-plane orientation of 5% or more, which is determined by a Lotgering method using an X-ray diffraction profile in a range of 2?=20° to 70° obtained under X-ray irradiation, and an XRC half width of 15.0° or less in rocking curve measurement, an F content of less than 0.99 mass ppm when measured by D-SIMS, a crystal grain diameter of 15 to 200 ?m, and 25 or less pores having a diameter of 0.2 ?m to 1.0 ?m when a photograph of a viewing area 370.0 ?m in a vertical direction and 372.0 ?m in a horizontal direction taken at a magnification factor of 1000 is visually observed.

Abstract: An alumina sintered body according to the present invention includes a surface having a degree of c-plane orientation of 5% or more, the degree of c-plane orientation being determined by a Lotgering method using an X-ray diffraction profile obtained through X-ray irradiation at 2?=20° to 70°. The alumina sintered body contains Mg and F, a Mg/F mass ratio is 0.05 to 3500, and a Mg content is 30 to 3500 ppm by mass. The alumina sintered body has a crystal grain size of 15 to 200 ?m. When a field of view of 370.0 ?m long×372.0 ?m wide is photographed with a 1000-fold magnification and the photograph is visually observed, a number of pores having a diameter of 0.2 to 0.6 ?m is 250 or less.

Abstract: A method for producing a transparent alumina sintered body includes (a) the step of preparing an alumina raw material powder containing a plate-like alumina powder having an aspect ratio of 3 or more so that the mass ratio R1 of F to Al in the alumina raw material powder is 5 ppm or more, and forming a compaction raw material containing the alumina raw material powder into a compact, and (b) the step of pressure-sintering the compact at a temperature at which F evaporate to yield a transparent alumina sintered body.

Abstract: An alumina sintered body according to the present invention has a degree of c-plane orientation of 90% or more as determined by Lotgering's method from an X-ray diffraction profile obtained by irradiating a plate surface with X-rays in a range of 2?=20° to 70°. The alumina sintered body has no pores when a cross-sectional surface formed in a direction perpendicular to the plate surface is polished using an Ar+ ion beam and a mask and is examined under a scanning electron microscope at a magnification of 5,000 times. The alumina sintered body has a total mass fraction of impurity elements other than Mg and C of 100 ppm or less. This alumina sintered body has a high degree of orientation, high density, and high purity and thus has a higher optical translucency than those known in the art.

Abstract: A method for producing a transparent alumina sintered body according to the present invention includes (a) a step of preparing an alumina raw material powder containing a plate-like alumina powder having an aspect ratio of 3 or more and a fine alumina powder having an average particle diameter smaller than that of the plate-like alumina powder so that, when a mixing ratio of the plate-like alumina powder to the fine alumina powder in terms of mass ratio is assumed to be T:(100?T), T is 0.001 or more and less than 1, and so that a mass ratio R1 of F relative to A1 in the alumina raw material powder is less than 15 ppm; (b) a step of forming a raw material for forming containing the alumina raw material powder into a compact; and (c) a step of sintering the compact so as to obtain a transparent alumina sintered body.

Abstract: An alumina sintered body of the present invention has a degree of c-plane orientation of 5% or more, which is determined by a Lotgering method using an X-ray diffraction profile in a range of 2?=20° to 70° obtained under X-ray irradiation, and an XRC half width of 15.0° or less in rocking curve measurement, an F content of less than 0.99 mass ppm when measured by D-SIMS, a crystal grain diameter of 15 to 200 ?m, and 25 or less pores having a diameter of 0.2 ?m to 1.0 ?m when a photograph of a viewing area 370.0 ?m in a vertical direction and 372.0 ?m in a horizontal direction taken at a magnification factor of 1000 is visually observed.

Abstract: An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 1° or more and 3° or less and an average sintered grain size of 20 ?m or more.

Abstract: An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 0.1° or more and less than 1.0° and an average sintered grain size of 10 ?m or more.

Abstract: An alumina sintered body according to the present invention includes a surface having a degree of c-plane orientation of 5% or more, the degree of c-plane orientation being determined by a Lotgering method using an X-ray diffraction profile obtained through X-ray irradiation at 2?=20° to 70°. The alumina sintered body contains Mg and F, a Mg/F mass ratio is 0.05 to 3500, and a Mg content is 30 to 3500 ppm by mass. The alumina sintered body has a crystal grain size of 15 to 200 ?m. When a field of view of 370.0 ?m long×372.0 ?m wide is photographed with a 1000-fold magnification and the photograph is visually observed, a number of pores having a diameter of 0.2 to 0.6 ?m is 250 or less.

Abstract: An alumina sintered body according to the present invention has a degree of c-plane orientation of 90% or more as determined by Lotgering's method from an X-ray diffraction profile obtained by irradiating a plate surface with X-rays in a range of 2?=20° to 70°. The alumina sintered body has no pores when a cross-sectional surface formed in a direction perpendicular to the plate surface is polished using an Ar+ ion beam and a mask and is examined under a scanning electron microscope at a magnification of 5,000 times. The alumina sintered body has a total mass fraction of impurity elements other than Mg and C of 100 ppm or less. This alumina sintered body has a high degree of orientation, high density, and high purity and thus has a higher optical translucency than those known in the art.