Provided is a method for producing a silicon nitride sintered body including: a step of molding and firing a raw material powder containing silicon nitride, in which an α-conversion rate of the silicon nitride contained in the raw material powder is less than or equal to 30 mass %. A thermal conductivity (at 20° C.) of the silicon nitride sintered body exceeds 100 W/m.Math.K and a fracture toughness (K.sub.IC) is greater than or equal to 7.4 MPa.Math.m.sup.1/2.

A ceramic green sheet including a plurality of substrate forming regions. A barcode or a two-dimensional code is drawn in a portion of the ceramic green sheet. The barcode or the two-dimensional code is obtained by encoding one or more of the following information. Information relating to raw materials used when the ceramic green sheet is produced, information relating to molding conditions of the ceramic green sheet, information relating to a release agent used when a plurality of the ceramic green sheets are stacked, or a serial number.

Methods and systems for manufacturing a ceramic or glass material component supersaturated in nitrogen are disclosed. The method for manufacturing a component typically comprises receiving the ceramic or glass material within a containment vessel; simultaneously heating and applying isostatic pressure to the ceramic or glass material within the containment vessel to a first temperature and a first pressure using pressurizing nitrogen gas; holding the first temperature and the first pressure for a period of time; cooling the ceramic or glass material within the containment vessel to a second temperature while maintaining the first pressure; and depressurizing the containment vessel to a second pressure.

Provided are a method for producing a ceramic sintered body having improved light emission intensity, a ceramic sintered body, and a light emitting device. The method for producing a ceramic sintered body comprises preparing a molded body that contains a nitride fluorescent material having a composition containing: at least one alkaline earth metal element M.sup.1 selected from the group consisting of Ba, Sr, Ca, and Mg; at least one metal element M.sup.2 selected from the group consisting of Eu, Ce, Tb, and Mn; Si; and N, wherein a total molar ratio of the alkaline earth metal element M.sup.1 and the metal element M.sup.2 in 1 mol of the composition is 2, a molar ratio of the metal element M.sup.2 is a product of 2 and a parameter y and wherein y is in a range of 0.001 or more and less than 0.5, a molar ratio of Si is 5, and a molar ratio of N is 8, and wherein the nitride fluorescent material has a crystallite size, as calculated by X-ray diffraction measurement using the Halder-Wagner method, of 550 Å or less, and calcining the molded body at a temperature in a range of 1,600° C. or more and 2,200° C. or less to obtain a sintered body.

Provided is a method for continuously producing a silicon nitride sintered compact for enabling a continuous production of silicon nitride sintered compacts by sintering using a silicon nitride powder having a high β-phase rate. A fired compact 1 housed in a firing jig 2 contains a silicon nitride powder having at least 80% of β-transition rate and 7 to 20 m.sup.2/g of specific surface area together with a sintering additive, where the total content of aluminum element is adjusted not to exceed 800 ppm. The firing jig 2 is supplied into a continuous firing furnace equipped with a closed-type firing container 5 having at its end portions a supplying openable door 3 and a discharging openable door 4 for supplying and discharging the firing jig, a heating mechanism 6 provided on the body periphery of the firing container 5, a conveyance mechanism for supplying/discharging the firing jig into/from the firing container, and a gas-supplying mechanism for supplying an inert gas into the firing container, so that the silicon nitride is heated to a temperature in the range of 1200 to 1800° C. in an inert gas atmosphere and at a pressure of not less than 0 MPa.Math.G and less than 0.1 MPa.Math.G so as to be sintered.

According to an embodiment, a silicon nitride sintered body includes silicon nitride crystal grains and a grain boundary phase, and in a case where Raman spectroscopy of a 20 μm×20 μm region in a central cross section of the silicon nitride sintered body is performed, two or more peaks are detected in ranges of 780 cm.sup.−1 to 810 cm.sup.−1 and 1340 cm.sup.−1 to 1370 cm.sup.−1, and four to six peaks are detected in ranges of 170 cm.sup.−1 to 190 cm.sup.−1, 607 cm.sup.−1 to 627 cm.sup.−1, 720 cm.sup.−1 to 740 cm.sup.−1, and 924 cm.sup.−1 to 944 cm.sup.−1.

According to an embodiment, a silicon nitride sintered body includes silicon nitride crystal grains and a grain boundary phase, and in a case where Raman spectroscopy of a 20 μm×20 μm region in a central cross section of the silicon nitride sintered body is performed, two or more peaks are detected in ranges of 780 cm.sup.−1 to 810 cm.sup.−1 and 1340 cm.sup.−1 to 1370 cm.sup.−1, and four to six peaks are detected in ranges of 170 cm.sup.−1 to 190 cm.sup.−1, 607 cm.sup.−1 to 627 cm.sup.−1, 720 cm.sup.−1 to 740 cm.sup.−1, and 924 cm.sup.−1 to 944 cm.sup.−1.

A method is disclosed for forming a blended phosphor composition. The method includes the steps of firing precursor compositions that include europium and nitrides of at least calcium, strontium and aluminum, in a refractory metal crucible and in the presence of a gas that precludes the formation of nitride compositions between the nitride starting materials and the refractory metal that forms the crucible. The resulting compositions can include phosphors that convert frequencies in the blue portion of the visible spectrum into frequencies in the red portion of the visible spectrum.

A method is disclosed for forming a blended phosphor composition. The method includes the steps of firing precursor compositions that include europium and nitrides of at least calcium, strontium and aluminum, in a refractory metal crucible and in the presence of a gas that precludes the formation of nitride compositions between the nitride starting materials and the refractory metal that forms the crucible. The resulting compositions can include phosphors that convert frequencies in the blue portion of the visible spectrum into frequencies in the red portion of the visible spectrum.

A method is disclosed for forming a blended phosphor composition. The method includes the steps of firing precursor compositions that include europium and nitrides of at least calcium, strontium and aluminum, in a refractory metal crucible and in the presence of a gas that precludes the formation of nitride compositions between the nitride starting materials and the refractory metal that forms the crucible. The resulting compositions can include phosphors that convert frequencies in the blue portion of the visible spectrum into frequencies in the red portion of the visible spectrum.