Abstract: A method for producing a single crystal or polycrystal of terbium aluminate containing at least terbium, aluminum and oxygen and represented by the formula Tb.sub.1-x Al.sub.1+x O.sub.3 wherein -0.5.ltoreq.x.ltoreq.0.5, which comprises growing the single crystal or polycrystal using a reducing gas atmosphere or a neutral gas atmosphere as an atmosphere for crystal growth.

Abstract: A high strength and toughness .beta.-silicon nitride sintered body suitable for the material of a variety of structural parts. The sintered body contains .beta.-silicon nitride (Si.sub.3 N.sub.4) in an amount not less than 95% by weight of total silicon nitride; oxygen in a total amount not more than 3% by weight of the sintered body; and columnar grains each of which has a diameter not less than 5 .mu.m and an aspect ratio not less than 5, the columnar grains being in an amount not less than 0.5% by volume of total of raw materials in the sintered body; the sintered body having a bulk density not less than 96% of a theoretical density. Such a sintered body is produced by a method comprising the following steps in the sequence set forth: preparing powder of a starting material including .beta.-silicon nitride in an amount not less than 80% by weight of the starting material; adding oxide of at least one element selected from the group IIIa of the periodic table of elements in an amount ranging from 0.

Abstract: An ohmic electrode is formed on a cBN crystal to form a cBN semiconductor device which is used as a solid electronic element. The cBN semiconductor device may be of an n-type, a p-type or a pn junction type wherein molybdenum is deposited onto an n-type doped region of the cBN crystal or platinum is deposited onto a p-type doped region to thereby form an electrode with ohmic characteristic. The deposition of the molybdenum or the platinum is conducted by using a vapor deposition method followed by heating the attached substance at a temperature of 300.degree. C.-1100.degree. C. in an inactive gas atmosphere. The cBN semiconductor device can be used as a solid electronic element or an optoelectronic element for rectifiers, transistors, light emitting diodes and so on and integrated elements thereof.

Abstract: A computer-aided class composition design apparatus includes a memory device having stored therein glass component compound data and glass physical property data. A display device is used for initially displaying a plurality of glass component compounds from among the glass component compound data. Using an input device, a glass composition is selected from among the displayed glass components. The glass physical property data is processed to approximate at least one physical property of the selected glass composition. Alternately, the glass physical properties themselves are displayed and values assigned thereto, and the component compound data and glass physical property data are processed to obtain a glass composition having approximated physical property values in accordance with the selected physical property values.

Abstract: An ohmic electrode is formed on a cBN crystal to form a cBN semiconductor device which is used as a solid electronic element. The cBN semiconductor device may be of an n-type, a p-type or a pn junction type wherein molybdenum is deposited onto an n-type doped region of the cBN crystal or platinum is deposited onto a p-type doped region to thereby form an electrode with ohmic characteristic. The deposition of the molybdenum or the platinum is conducted by using a vapor deposition method followed by heating the attached substance at a temperature of 300.degree. C.-1100.degree. C. in an inactive gas atmosphere. The cBN semiconductor device can be used as a solid electronic element or an optoelectronic element for rectifiers, transistors, light emitting diodes and so on and integrated elements thereof.

Abstract: A high strength and toughness .beta.-silicon nitride sintered body suitable for the material of a variety of structural parts. The sintered body contains .beta.-silicon nitride (Si.sub.3 N.sub.4) in an amount not less than 95% by weight of total silicon nitride; oxygen in a total amount not more than 3% by weight of the sintered body; and columnar grains each of which has a diameter not less than 5 .mu.m and an aspect ratio not less than 5, the columnar grains being in an amount not less than 0.5% by volume of total of raw materials in the sintered body; the sintered body having a bulk density not less than 96% of a theoretical density. Such a sintered body is produced by a method comprising the following steps in the sequence set forth: preparing powder of a starting material including .beta.-silicon nitride in an amount not less than 80% by weight of the starting material; adding oxide of at least one element selected from the group IIIa of the periodic table of elements in an amount ranging from 0.

Abstract: It is an object of the present invention to obtain a high quality YB66 crystal by lowering the temperature of the molten zone and growing a crystal by deposition growth under an incongruent condition. A method for preparing a yttrium 66 boride crystal by the floating zone method by use of a YB66 polycrystalline rod. A YB66 crystal having a composition with an atomic ratio B/Y within a range of from 50 to 75, is grown under such conditions that the melt has a composition (an atomic ratio B/Y) different from the raw YB66 polycrystalline rod and the growing YB66 crystal, and that an equilibrium is maintained at the growth interface. When the atomic ratio B/Y of the starting material is within the range of from 50 to 62 and the atomic ratio B/Y of the melt is within the range of from 40 to 62, it is possible to attain the atomic ratio B/Y of the growing crystal within the range of from 50 to 62.

Abstract: A method of making hard boron nitride by a plasma CVD method employing beam irradiation comprising the steps of: introducing a boron source gas and a nitrogen source gas into a plasma generated by employing a working gas selected from the group consisted of helium, hydrogen and a mixture of these under pressure of 0.01 through 100 torr, said boron source gas and said nitrogen source gas are provided with volumetric percent of 0.01 through 10% with respect to the working gas; transmitting activating innoculations formed in the plasma to a substrate of which temperature is maintained at 300.degree. through 1100.degree. C; converting the activating innoculations into precursor activating innoculations necessary for forming and growing a hard boron nitride film on the substrate by irradiating an ultraviolet beam to the activation innoculations on the substrate; and accumulating the hard boron nitride on the substrate.

Abstract: The present invention relates to a lanthanum boride type single crystal having the chemical formula (La.sub.1-x M.sub.x)B.sub.6 (0.01.ltoreq.x.ltoreq.0.50) wherein M is at least one rare earth element selected from the group consisting of Ce, Pr, Nd, Sm and Gd, and further relates to a method for growing a lanthanum boride type single crystal by fusion method, which comprises using a lanthanum boride starting material containing from 1 to 50 mol % of at least one rare earth boride selected from the group consisting of CeB.sub.6, PrB.sub.6, NdB.sub.6, SmB.sub.6 and GdB.sub.6.

Abstract: A process for producing a powder material for niobium-containing lead perovskite ceramics represented by the general formula:PbA.sub.x Nb.sub.1-x O.sub.3,wherein X=1/2 or 1/3, A represents at least one element selected from the group consisting of Fe, Co, Cr, Ni, Mn, Mg, Zn, Cd, Zr, In, Cu and Hf. A dried mixture of a sol or a suspension of a hydroxide a component A which has a lower activity than Pb and a niobic acid sol is first calcinated. A Pb compound is then added with the mixture and the resultant mixture is calcinated again.

Abstract: A process for producing a peroxoniobic acid sol which comprises: adding a strong acid, hydrogen peroxide and water to at least one niobium compound selected from the group consisting of niobium hydroxide, niobium oxide and niobium pentachloride to provide an aqueous solution of peroxoniobic acid; and then maintaining the aqueous solution at a temperature of 5.degree.-50.degree. C.

Abstract: A process for producing a high density ceramic of perovskite represented by the formula:ABO.sub.

Abstract: A method for separating sodium and potassium from an aqueous solution containing such metals, which comprises selectively ion-exchanging sodium and potassium with titania hydrate (TiO.sub.2 .multidot.nH.sub.2 O where n=1 to 2) obtained by treating potassium titanate to remove potassium therefrom, followed by a reaction at a temperature of from 25.degree. to 80.degree. C. to desorb and purify sodium and potassium.

Abstract: A gadolinium-lutetium-gallium garnet crystal having the formula:(Gd.sub.1-x Lu.sub.x).sub.3 (Gd.sub.y Lu.sub.z Ga.sub.1-y-z).sub.z Ga.sub.3 O.sub.12 (I)wherein x, y and z are number satisfying 0.ltoreq.x.ltoreq.0.4, 0.ltoreq.y.ltoreq.0.05 and 0.6.ltoreq.z.ltoreq.1.0, respectively.

Abstract: An apparatus for synthesizing diamond, which comprises a reaction chamber, a means for supplying to the reaction chamber a gas mixture comprising a hydrogen gas and an organic compound decomposable by a plasma to form a diamond or a gas mixture comprising a hydrogen gas, an inert gas and said organic compound, a means of conducting a microwave of frequency larger than 300 MHz to the reaction chamber to generate a microwave plasma in the gas mixture and a substrate held by a substrate holder to locate in the microwave plasma and on which diamond is to be formed, wherein the microwave conducting means is designed to introduce the microwave to the reaction chamber from a plurality of directions.

Abstract: A method for preparing diamond or diamond-like carbon, which comprises exciting carbon by decomposing, evaporating and dissociating an organic compound or a carbon material in a combustion flame of at least 600.degree. C. of a hydrocarbon, hydrogen or a mixture thereof and oxygen gas or air, mixing thereto hydrogen in an amount of at least one time by volume the amount of carbon, and maintaining the mixture at a temperature of from 600.degree. to 1,700.degree. C. to precipitate diamond or diamond-like carbon.

Abstract: Aqueous titanium tetrachloride solution, i.e., one component (X) for forming multi-component ceramic compound, and a suitable amount of zirconium oxynitrate, i.e., another component (Y) are mixed. Hydroxide coprecipitate of Ti.sup.4+ and Zr.sup.4+ containing the components is formed from the mixture solution. The coprecipitate is cleaned, dried, then calcined, for example, at 1100.degree. C., thus producing powder containing 0.32-micron particles. This powder is mixed with TiO.sub.2 and PbO, in a suitable amount to be added to the other component (Y) of the multi-component ceramic compound. The resultant mixture is calcined, for example, at 740.degree. for 1 hour, into fine powder containing 0.32-micron particles. The calcined powder is then press-molded, for example, under the pressure of 1 ton/cm.sup.2, then calcined, for example, at 1220.degree. C. for 1 hour, thereby forming multi-component ceramics.

Abstract: A method for preparing needle-like, fibrous or porous diamond, or an aggregate thereof, which comprises subjecting diamond synthesized by a chemical vapor deposition method or a plasma-assisted vapor deposition method, or a film of such diamond, to plasma treatment in a gas stream containing oxygen, carbon dioxide, steam, hydrogen, a halogenated hydrocarbon or a halogenated carbon, or to thermal oxidation treatment in a gas stream containing oxygen, carbon dioxide or steam, for etching.

Abstract: A process for producing boron nitride comprises heating a mixture consisting of borohydride of alkali metal and ammonium chloride at a temperature range of from 800.degree. to 2200.degree. C. in a non-oxidizing atmosphere.

Abstract: A field emission type electron gun comprises a cathode, an anode placed opposing the cathode, a filament placed obliquely above the anode in a space between the cathode and anode to heat the anode, a control electrode and a vacuum container housing the cathode, the anode the control electrode and the filament. The anode has an elongated body with a through hole at its center, the control electrode is provided near the anode, and means for rendering the electric potential of the control electrode to be negative to the electric potential of the anode is provided to concentrate an electron beam to the top end of the anode.