Abstract: A device for producing a tubular single crystal comprises a crucible, a heating means, a die disposed in the crucible, having an annular slit, and a pulling-up means. The upper surface of the die includes an upward slope that increases in height from the annular slit to an inner diameter side and an outer diameter side, respectively, progressing away from the annular slit, wherein the maximum height of the slope on the inner diameter side (H1) is greater than the maximum height of the slope on the outer diameter side (H2) and the difference (H1?H2) is 0.1 mm or more and less than 7.5 mm.

Abstract: A sapphire ribbon of the present disclosure has a width, a thickness, and a length that are orthogonal to one another, a length direction is a growth direction, and the sapphire ribbon further has two main surfaces separate from each other in a thickness direction, and the width is at least 40 cm. Further, a monocrystalline ribbon manufacturing apparatus using EFG method according to the present disclosure includes a crucible having a width greater than a depth thereof, a die pair installed in the crucible and facing each other across a slit in the depth direction, a first heater and a second heater disposed around the crucible and facing each other in the depth direction, and a third heater and a fourth heater disposed around the crucible and facing each other in the width direction.

Abstract: A device for producing a tubular single crystal comprises a crucible, a heating means, a die disposed in the crucible, having an annular slit, and a pulling-up means. The upper surface of the die includes an upward slope that increases in height from the annular slit to an inner diameter side and an outer diameter side, respectively, progressing away from the annular slit, wherein the maximum height of the slope on the inner diameter side (H1) is greater than the maximum height of the slope on the outer diameter side (H2) and the difference (H1?H2) is 0.1 mm or more and less than 7.5 mm.

Abstract: A single crystal of the present disclosure is a plate-shaped body having two main surfaces that are opposite to each other, and has bubbles arranged in a plurality of line shapes parallel to the main surface in a region within a depth of 0.5 mm from either one of the main surfaces. Additionally, a single crystal of the present disclosure is a plate-shaped body having two main surfaces that are opposite to each other, and has bubbles arranged in a plurality of line shapes parallel to the main surface within a region from either one of the main surfaces to ¼ of the thickness which is a distance between the main surfaces.

Abstract: A sapphire ribbon of the present disclosure has a width, a thickness, and a length that are orthogonal to one another, a length direction is a growth direction, and the sapphire ribbon further has two main surfaces separate from each other in a thickness direction, and the width is at least 40 cm. Further, a monocrystalline ribbon manufacturing apparatus using EFG method according to the present disclosure includes a crucible having a width greater than a depth thereof, a die pair installed in the crucible and facing each other across a slit in the depth direction, a first heater and a second heater disposed around the crucible and facing each other in the depth direction, and a third heater and a fourth heater disposed around the crucible and facing each other in the width direction.

Abstract: A cordierite ceramic contains a main component having a composition including Mg of 12.6% by mass or more and 14.0% by mass or less in terms of an oxide, Al of 33.4% by mass or more and 34.4% by mass or less in terms of an oxide and Si of 52.0% by mass or more and 53.6% by mass or less in terms of an oxide, an accessory component having any one of Y, Yb, Er, and Ce in an amount of 4.5% by mass or more and 15.0% by mass or less in terms of an oxide based on 100% by mass of the main component, wherein cordierite, disilicate and spinel are present as crystal phases, a coefficient of thermal expansion of ?120 ppb/° C. to +120 ppb/° C., a four-point bending strength of 170 MPa or more, a low thermal expansion performance and an excellent mechanical strength.