Abstract: A method for adding hydrogen-containing and/or nitrogen-containing compounds to a nitrogen-containing solvent used during ammonothermal growth of group-Ill nitride crystals to offset decomposition products formed from the nitrogen-containing solvent, in order to shift the balance between the reactants, i.e. the nitrogen-containing solvent and the decomposition products, towards the reactant side.

Abstract: Affords nitride semiconductor crystal manufacturing apparatuses that are durable and that are for manufacturing nitride semiconductor crystal in which the immixing of impurities from outside the crucible is kept under control, and makes methods for manufacturing such nitride semiconductor crystal, and the nitride semiconductor crystal itself, available. A nitride semiconductor crystal manufacturing apparatus (100) is furnished with a crucible (101), a heating unit (125), and a covering component (110). The crucible (101) is where, interiorly, source material (17) is disposed. The heating unit (125) is disposed about the outer periphery of the crucible (101), where it heats the crucible (101) interior. The covering component (110) is arranged in between the crucible (101) and the heating unit (125).

Abstract: A method and system for producing quantum confined metal nitride. The method includes immersing two electrodes into a nitrogen environment wherein at least one electrode includes an indium electrode, and passing an arc between the electrodes. The system includes a container for holding a bath of liquid nitrogen, two electrodes disposed inside the container so as to be immersed into the bath of liquid nitrogen, at least one of the two electrodes being a metal electrode, and a voltage source connected to the electrodes and configured to pass an arc between the electrodes.

Abstract: Rare earth-activated aluminum nitride powders are made using a solution-based approach to form a mixed hydroxide of aluminum and a rare earth metal, the mixed hydroxide is then converted into an ammonium metal fluoride, preferably a rare earth-substituted ammonium aluminum hexafluoride ((NH4)3Al1-xRExF6), and finally the rare earth-activated aluminum nitride is formed by ammonolysis of the ammonium metal fluoride at a high temperature. The use of a fluoride precursor in this process avoids sources of oxygen during the final ammonolysis step which is a major source of defects in the powder synthesis of nitrides. Also, because the aluminum nitride is formed from a mixed hydroxide co-precipitate, the distribution of the dopants in the powder is substantially homogeneous in each particle.

Abstract: Affords group III nitride crystal growth methods enabling crystal to be grown in bulk by a liquid-phase technique. One such method of growing group III nitride crystal from solution is provided with: a step of preparing a substrate having a principal face and including at least on its principal-face side a group III nitride seed crystal having the same chemical composition as the group III nitride crystal, and whose average density of threading dislocations along the principal face being 5×106 cm?2 or less; and a step of bringing into contact with the principal face of the substrate a solution in which a nitrogen-containing gas is dissolved into a group III metal-containing solvent, to grow group III nitride crystal onto the principal face.

Abstract: A method of growing a group III nitride crystal grows a group III nitride crystal from a solution in which an alkaline metal, a group III metal and nitrogen are dissolved, and includes, in the solution, a material which increases solubility of the nitrogen into the solution.

Abstract: Means for a thermally conductive and electrically insulating material 1 containing an AlN crystal 150 mainly comprising AlN, and a production method thereof. In production, a molten aluminum layer is formed on an AlN substrate 11 with at least its surface comprising AlN in an atmosphere of a non-oxidizing gas, and the molten aluminum layer is then heated in an atmosphere of N2 gas to form an AlN crystal 150 which mainly comprises an AlN layer 125. The means are also a thermally conductive and electrically insulating material having an AlN crystal and an Al gradient layer, and a production method thereof. In production, a heating step of forming a molten aluminum layer 15 on the AlN layer 125 and heating it in an atmosphere of N2 gas is repeated at least twice or more. At this time, the amount of the N2 gas dissolved in the molten aluminum layer is decreased as the heating step is repeated.

Abstract: A colloidal suspension of III-V semiconductor nanoparticles.

Abstract: A process for producing an aluminum nitride sintered body having improved light transmission properties includes the step of subjecting an ordinary aluminum nitride sintered body to thermal treatment in an inert atmosphere at a temperature of from 1300 to 1400° C. for at least 1 hr. A cover for light sources is produced by the process and includes a hollow aluminum nitride sintered body having a light transmittance in the visible light region of at least 87%, which body is obtainable by thermally treating a hollow aluminum nitride sintered body in an inert atmosphere at a temperature of 1300 to 1400° C. for at least 1 hr.

Abstract: In a method of manufacturing an aluminum nitride single crystal film on a substrate by heating a sapphire substrate in the presence of carbon, nitrogen and carbon monoxide, an aluminum compound which differs from the raw material sapphire substrate and the formed aluminum nitride single crystal and can control the concentration of aluminum in the heating atmosphere, such as aluminum nitride or alumina, is made existent in a reaction system to promote a reduction nitriding reaction. An aluminum nitride single crystal multi-layer substrate having an aluminum nitride single crystal film on the surface of a sapphire substrate, wherein the aluminum nitride single crystal has improved crystallinity and a low density of defects, is provided.

Abstract: An aluminum nitride-based ceramic sintered body is provided, which is manufactured by sintering an aluminum nitride powder comprising aluminum nitride as a main component, carbon in an amount of 0.1 wt % or more to 1.0 wt % or less, and containing oxygen in an amount that is not greater than 0.7 wt %, wherein carbon and oxygen are dissolved in grains of the aluminum nitride powder. The a-axis length of the lattice constant of the aluminum nitride is in a range of 3.1120 ? or more to 3.1200 ? or less, and the a c-axis length of the lattice constant is in a range of 4.9810 ? or more to 4.9900 ? or less. The volume resistivity of the aluminum nitride-based ceramic sintered body at 500° C. is 109 ?·cm or more.

Abstract: [Problems] To provide a method of producing, easily and in a high yield, a reformed aluminum nitride sintered body having very excellent light transmission property which can be favorably used as a light-transmitting cover particularly for light sources having high luminous efficiencies. [Means for Solution] An aluminum nitride sintered body having a concentration of metal impurities excluding aluminum of not more than 150 ppm, an oxygen concentration of not more than 0.5% by weight and a relative density of not less than 95% is used as a starting material. The aluminum nitride sintered body is heat-treated in an oxidizing atmosphere in a temperature region of 1400 to 2000° C. to increase the oxygen concentration by not less than 0.03% by weight.

Abstract: A method of growing a III group nitride single crystal by using a metal-organic chemical vapor deposition (MOCVD) process, the method including: preparing an r-plane (1-102) substrate; forming a nitride-based nucleation layer on the substrate; and growing a nonpolar a-plane nitride gallium single crystal on the nitride-based nucleation layer while altering increase and decrease of a ratio of V/III group to alternate a horizontal growth mode and a vertical growth mode.

Abstract: The invention relates to a method of manufacturing aluminium nitride, in which a multilayer structure including rolled aluminium-based products is prepared by stacking or winding, and it is heated under a nitrogenous atmosphere, the majority of the nitriding occurring during a phase in which the temperature of the nitrogenous atmosphere is maintained between 400° C. and 660° C. The invention makes it possible to obtain aluminium nitride via an economic method requiring neither the use of aluminium powder as a raw material nor the use of very high temperatures. The aluminium nitride obtained includes particles the microscopic structure of which is layered.

Abstract: In the direct production of GaN by the metathesis of Li3N and GaCl3 or GaBr3 or GaI3, the reaction rate and yields can be greatly enhanced by including diethyl ether in the reaction system.

Abstract: An aluminum nitride sintered body in which the ratio of a peak area S2 of a diffraction peak at 2?=34° or more and 35° or less corresponding to an aluminum oxynitride phase to a peak area S1 of a diffraction peak of an aluminum nitride crystal face [100] in X-ray diffraction, i.e. S2/S1, is 0.01 or more and 0.3 or less, and the spin concentration at a magnetic field between 336 mT and 342 mT as measured by an electron spin resonance method is 1×1015 spins/cm3 or more and 1×1020 spins/cm3 or less. This is manufactured by: mixing a predetermined amount of the aluminum nitride powder and the ?-alumina powder whose ratio of average particle diameter to that of aluminum nitride powder is within the range of 0.3 or more and 0.8 or less; and sintering the mixed powder at ambient-pressure.

Abstract: An aluminum nitride-based ceramic sintered body is provided, which is manufactured by sintering an aluminum nitride powder comprising aluminum nitride as a main component, carbon in an amount of 0.1 wt % or more to 1.0 wt % or less, and containing oxygen in an amount that is not greater than 0.7 wt %, wherein carbon and oxygen are dissolved in grains of the aluminum nitride powder. The a-axis length of the lattice constant of the aluminum nitride is in a range of 3.1120 ? or more to 3.1200 ? or less, and the a c-axis length of the lattice constant is in a range of 4.9810 ? or more to 4.9900 ? or less. The volume resistivity of the aluminum nitride-based ceramic sintered body at 500° C. is 109 ?·cm or more.

Abstract: To provide an aluminum nitride powder and an aluminum nitride sintered body which satisfy both high thermal conductivity of an aluminum nitride sintered body and reduction in the shrinkage factor at the time of sintering. An aluminum nitride powder characterized in that it has local maximum values in size in regions of from 3 to 15 ?m, from 0.5 to 1.5 ?m and 0.3 ?m or less, the proportions of particles in the respective regions are from 40 to 70%, from 25 to 40% and from 0.5 to 20% on the volume basis, and it has an oxygen amount of from 0.5 to 1.5 mass %. An aluminum nitride sintered body which is a sintered body of a powder mixture containing the above aluminum nitride powder and a sintering aid, characterized by having a thermal conductivity of at least 190 W/m·K and a shrinkage factor represented by the percentage of {(dimensions of the molded body before sintering)?(dimensions of the sintered body after sintering)}/(dimensions of the molded body before sintering) of at most 15%.

Abstract: An AlxGayIn1-x-yN substrate in which particles having a grain size of at least 0.2 ?m on a surface of the AlxGayIn1-x-yN substrate are at most 20 in number when a diameter of the AlxGayIn1-x-yN substrate is two inches, and a cleaning method with which the AlxGayIn1-x-yN substrate can be obtained are provided. Further, an AlxGayIn1-x-yN substrate in which, in a photoelectron spectrum of a surface of the AlxGayIn1-x-yN substrate by X-ray photoelectron spectroscopy with a detection angle of 10°, a ratio between a peak area of C1s electrons and a peak area of N1s electrons (C1s electron peak area/N1s electron peak area) is at most 3, and a cleaning method with which the AlxGayIn1-x-yN substrate can be obtained are provided.

Abstract: The present invention provides compositions and a novel high-yielding process for preparing high purity Group III nitrides. The process involves heating a Group III metal and a catalytic amount of a metal wetting agent in the presence of a nitrogen source. Group III metals can be stoichiometrically converted into high purity Group III nitride powders in a short period of time. The process can provide multi-gram quantities of high purity Group III nitrides in relatively short reaction times. Detailed characterizations of GaN powder were preformed and are reported herein, including morphology and structure by SEM and XRD, optical properties by cathodoluminescence (CL), and Raman spectra to determine the quality of the GaN particles. The purity of GaN powder was found to be greater than 99.9% pure, as analyzed by Glow Discharge Mass Spectrometry (GDMS). Green, yellow, and red light emission can be obtained from doped GaN powders.

Abstract: The present invention is to produce an aluminum nitride powder which is turned into a sintered body at a temperature of not more than 1600° C., thereby obtaining a sintered aluminum nitride in which the density and thermal conductivity are high and which can be properly used as a substrate material. Using a vapor phase reaction apparatus shown in FIG. 1, ammonia gas was fed from a reactor 2 heated at from 300 to 500° C. and maintained at that temperature by a heating section 1 via a feeding tube 4 while being regulated by a flow regulator 3. At the same time, while being regulated by the flow regulator 5, nitrogen gas containing an organic aluminum compound is fed via a feeding tube 6 to obtain an aluminum nitride powder. The aluminum nitride powder is subjected to a heat treatment at from 1100 to 1500° C. in a reducing gas atmosphere and/or an inert gas atmosphere to obtain an aggregate aluminum nitride powder.

Abstract: A porous aluminum fluoride on which SbClxF5-x (wherein x represents a numeral of 0 to 5) is supported, SbClxF5-x being obtainable by supporting SbCl5, or the like on a porous aluminum fluoride and treating it with hydrogen fluoride. The resulting porous aluminum fluoride has a high activity as a fluorinating agent, a fluorination catalyst, or the like, is easy to handle, can be used for a flow-type reaction, and also can be used even at a high temperature.

Abstract: A method for synthesizing aluminum nitride is disclosed, wherein an ignition agent is formed by mixing an azide powder (such as sodium azide; NaN3) and aluminum powder, and is paved on an ignition portion of a reactant-containing body having a plurality of ratios of aluminum to a diluent, wherein the content of the diluent is gradually increased in accordance with the propagation direction of combustion wave generated in the combustion synthesis process. The method for synthesizing aluminum nitride is to ignite the ignition agent located in the ignition portion of the reactant-containing body under an ambience in which the pressure is less than 1 atm, and to introduce nitrogen gas as the nitrogen source into the reaction chamber after ignition.

Abstract: A method of manufacturing a powder, by which it is possible to adjust the strength of the obtained powder is provided. The manufacturing method of a powder involves a step of preparing a slurry containing agglomerated particles of a synthetic material which is produced by reacting a first material and a second material under agitation, and a step of drying the slurry to obtain a powder of the synthetic material. The method has a feature that the particle size of the agglomerated particles is adjusted by, in the step of preparing a slurry, controlling agitation power for agitating the slurry. In the step of preparing a slurry, it is preferable that the slurry is initially agitated at a first agitation power, and at the time when the viscosity of the slurry approaches its maximum value, or at the time when the pH value of the slurry reaches the vicinity of the isoelectric point of the synthetic material, the agitation power is lowered from the first agitation power to a second agitation power.

Abstract: A method of manufacturing a nanocrystallite from a M-containing salt forms a nanocrystallite. The nanocrystallite can be a member of a population of nanocrystallites having a narrow size distribution and can include one or more semiconductor materials. Semiconducting nanocrystallites can photoluminesce and can have high emission quantum efficiencies.

Abstract: A process for producing aluminum nitride includes a nitrogen occluding step and a nitriding step. In the nitrogen occluding step, nitrogen is occluded in an aluminum powder having an average particle diameter of from 10 to 200 ?m by holding the aluminum powder in a nitrogen gas atmosphere of 460° C. or more for 10 minutes or more. In the nitriding step, the aluminum powder with nitrogen occluded therein is nitrided by developing a nitriding reaction at a temperature of from 500 to 1,000° C. while holding the aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 80 to 300 kpa. Thus, aluminum nitride, in which aluminum is inhibited from remaining and which has small particle diameters, is calcined at a lower temperature and is actively used to make high-quality substrates, can be produced at a lower temperature with a high yield.

Abstract: A method and an apparatus for preparing aluminum nitride are disclosed. The method for preparing aluminum nitride is first to prepare a reactant-containing body filled with admixtures of aluminum powder, a diluent (aluminum nitride powder) and nitrogen-containing solid compound, the reactant-containing body having an ignition portion, a propagating portion, a sustaining portion and an ending portion. Thereafter, the reactant-containing body is placed on a base having through holes in a reaction chamber, and preheated to a predetermined temperature for a predetermined period of time. Then, a re-circulating nitrogen gas is introduced through the reactant-containing body, and coolant is re-circulated between an inner wall and an outer wall of the reaction chamber, and then the ignition portion is ignited to perform a combustion synthesis process, thereby preparing the aluminum nitride, thereby preparing the aluminum nitride.

Abstract: A process for producing aluminum nitride includes a step of holding an aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 105 to 300 kPa, thereby developing a nitriding reaction at a temperature of from 500 to 1,000° C., wherein a reaction controller gas, controlling the development of the nitriding reaction, is supplied into a reactor chamber in which the aluminum powder is accommodated. In the production process, the reaction controller gas is included in the nitrogen atmosphere in the development of the nitriding reaction. Accordingly, the development of the nitriding reaction is controlled so that it is possible to develop the nitriding reaction at a lower temperature. As a result, it is possible to produce an aluminum nitride powder whose particle diameters are fine.

Abstract: A method of continuously producing a non-oxide ceramic formed of a metal constituent and a non-metal constituent. A salt of the metal constituent and a compound of the non-metal constituent and a compound of the non-metal constituent are introduced into a liquid alkali metal or a liquid alkaline earth metal or mixtures to react the constituents substantially submerged in the liquid metal to form ceramic particles. The liquid metal is present in excess of the stoichiometric amount necessary to convert the constituents into ceramic particles to absorb the heat of reaction to maintain the temperature of the ceramic particles below the sintering temperature. Ceramic particles made by the method are part of the invention.

Abstract: A process for producing aluminum nitride includes a nitrogen occluding step and a nitriding step. In the nitrogen occluding step, nitrogen is occluded in an aluminum powder having an average particle diameter of from 10 to 200 &mgr;m by holding the aluminum powder in a nitrogen gas atmosphere of 460° C. or more for 10 minutes or more. In the nitriding step, the aluminum powder with nitrogen occluded therein is nitrided by developing a nitriding reaction at a temperature of from 500 to 1,000° C. while holding the aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 80 to 300 kpa. thus, aluminum nitride, in which aluminum is inhibited from remaining and which has small particle diameters, is calcined at a lower temperature and is actively used to make high-quality substrates, can be produced at a lower temperature with a high yield.

Abstract: A method and an apparatus for preparing aluminum nitride are disclosed. The method includes the steps of (a) providing an aluminum container, (b) providing a reactant to be received in the aluminum container, and proceeding at least one step selected from a group consisting of step (b1), step (b2) and a combination thereof, (c) placing the aluminum container into a reactor with a specific pressure and introducing nitrogen gas into the reactor, and (d) heating the reactant at a specific temperature till igniting, thereby preparing the aluminum nitride. The step (b1) is placing a layer of an aluminum nitride powder between the reactant and the aluminum container, and the step (b2) is perpendicularly placing at least one aluminum pipe into the reactant.

Abstract: A surface treatment method for aluminum nitride includes the steps of:

Abstract: A process for producing aluminum nitride includes a step of holding an aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 105 to 300 kPa, thereby developing a nitriding reaction at a temperature of from 500 to 1,000° C., wherein a reaction controller gas, controlling the development of the nitriding reaction, is supplied into a reactor chamber in which the aluminum powder is accommodated. In the production process, the reaction controller gas is included in the nitrogen atmosphere in the development of the nitriding reaction. Accordingly, the development of the nitriding reaction is controlled so that it is possible to develop the nitriding reaction at a lower temperature. As a result, it is possible to produce an aluminum nitride powder whose particle diameters are fine.

Abstract: This invention provides a method for production of AlN powder. An Al powder was poured into a refractory container having an opening end. If the packing density of the Al powder was less than 0.8 g/cm3, the container containing the Al powder was placed in a reaction chamber filled with nitrogen. If the packing density was larger than 0.8 g/cm3, porous aluminum tubes were placed vertically in Al powder or an initiator was placed on top of the Al powder or both were taken. The container was then placed in the reaction chamber filled with nitrogen. A nitrogen stream was allowed to flow through the Al powder from the bottom to the top and the combustion synthesis reaction was ignited by heating the top surface of the reactant powder.

Abstract: An aluminum nitride sintered body contains aluminum nitride as a main component, at least one rare earth metal element in an amount of not less than 0.4 mol % and not more than 2.0 mol % as calculated in the form of an oxide thereof and aluminum oxide component in an amount of not less than 0.5 mol % and not more than 2.0 mol %. Si content of the sintered body is not more than 80 ppm and an average particle diameter of aluminum nitride grains is not more than 3 &mgr;m. The aluminum nitride sintered body hardly peels aluminum nitride grains and exhibits high resistivity of at least 108 &OHgr;·cm even in a high temperature range of, for example, 300-500° C., as well as relatively high thermal conductivity.

Abstract: A method and an apparatus for preparing aluminum nitride are disclosed. The method includes the steps of (a) providing an aluminum container, (b) providing a reactant to be received in the aluminum container, and proceeding at least one step selected from a group consisting of step (b1), step (b2) and a combination thereof, (c) placing the aluminum container into a reactor with a specific pressure and introducing nitrogen gas into the reactor, and (d) heating the reactant at a specific temperature till igniting, thereby preparing the aluminum nitride. The step (b1) is placing a layer of an aluminum nitride powder between the reactant and the aluminum container, and the step (b2) is perpendicularly placing at least one aluminum pipe into the reactant.

Abstract: This invention concerns a method for production of AlN powder. The reactants discovered in the invention are aluminum powder and a compound which contains NHx (e.g. NH2, NH3, NH4, N2H4, and N2H6 etc.) or halogens and which can be thermally decomposed or vaporized below the melting point of Al (660° C.). These two reactants are mixed at an appropriate ratio and then pressed into a compact with an appropriate shape. These two reactants, after being mixed at an appropriate ratio, may also be placed in a refractory container which has an opening at one end or has porous walls. In preparing the reactant compact or the reactant mixture, a dilutant such as AlN powder may also be added and mixed with the two reactants. This reactant compact or reactant mixture is then placed in a reaction chamber which is filled with nitrogen. By heating the reactant compact or the reactant mixture, the combustion synthesis reaction is ignited and AlN powder is produced.

Abstract: Processes are provided for preparation of precursors of Group III-V compounds, i.e., nitrides, phosphides, arsenides, antimonides and bismuthides of boron, aluminum, gallium and indium. The precursors are easily converted, e.g., by thermal decomposition, to the Group III-V compounds which are useful as thin-film coatings for aerospace components or as powders which may be shaped as desired.

Abstract: Nitride or oxidenitride based red to yellow pigments, such as tantalum(V) nitride and oxidenitrides containing tantalum may be produced by passing ammonia over nitridable metal compounds, in particular oxide compounds, at 700 to 1250° C. According to the invention, nitriding proceeds in a rotary tube or fluidised bed reactor in the presence of an oxide from the series SiO2, ZrO2, GeO2, SnO2, TiO2 and HfO2 under conditions under which this oxide is substantially not nitrided.

Abstract: Bulk, low impurity aluminum nitride (AlN) single crystals are grown by sublimation or similar deposition techniques at growth rates greater than 0.5 mm/hr.

Abstract: An aluminum-nitride sintered body that has both high thermal conductivity and high mechanical strength, a fabricating method for the same, and a semiconductor substrate comprising the same. A material powder is prepared by mixing an aluminum-nitride powder, constituting 1 to 95 wt. %, having an average particle diameter of 1.0 &mgr;m or less obtained by chemical vapor deposition, with another type or types of aluminum-nitride powders constituting the remaining part. The material powder is sintered in a non-oxidizing atmosphere to obtain a sintered body having an average grain diameter of 2 &mgr;m or less and a half width of the diffraction peak on the (302) plane, obtained by X-ray diffraction, of 0.24 deg. or less. Formation of a metallized layer on the sintered body yields a semiconductor substrate.

Abstract: A process for producing aluminum nitride comprises a step of nitriding directly a mixed powder comprising of, a bulky aluminum powder composed of aluminum or an aluminum alloy powder which occupies 50 to 97% by weight and whose sieve opening of JIS is not less than 210 .mu.m (70 mesh); and a nitriding accelerator powder composed of at least one kind of an aluminum powder and an aluminum alloy powder which occupy the balance of 50 to 3% by weight and whose sieve opening is less than 210 .mu.m (70 mesh); under a nitrogen gas atmosphere of the temperature ranging from 500 to 1000.degree. C. In the present invention, there can be obtained an aluminum nitride which is easy to be crushed by hand by using a mortar.

Abstract: A process for forming high quality crystalline refractory materials, particularly gallium (Ill) nitride (GaN), from solid precursors. By blending dry reactants in an oxygen and moisture free environment, placing the reactants in a sealed vessel, pressurizing the reactants to in excess of 5 kilobars (5000 atmospheres) and rapidly exposing the reactants to a temperature in excess of about 225.degree. C. The soluble salt by-products are then extracted from the resultant mixture, leaving high purity crystals of the nitride in the form of a fine powder.

Abstract: A transparent electrically conductive plate contains a transparent substrate, a transparent electrically conductive layer, an ultraviolet absorbing layer disposed between the transparent substrate and the transparent electrically conductive layer and containing an organic ultraviolet absorber, and an overcoating layer disposed between the transparent electrically conductive layer and the ultraviolet absorbing layer for protecting the ultraviolet absorbing layer.

Abstract: Near net-shapeable nanostructured ceramic nitride powder and a process for producing the same by nitriding molecular precursor powder in a nitrogen containing atmosphere, e.g., in ammonia, to form nanostructured ceramic nitride powder.

Abstract: A continuous process that produces nanoscale powders from different types of precursor material by evaporating the material and quenching the vaporized phase in a converging-diverging expansion nozzle. The precursor material suspended in a carrier gas is continuously vaporized in a thermal reaction chamber under conditions that favor nucleation of the resulting vapor. Immediately after the initial nucleation stages, the vapor stream is rapidly and uniformly quenched at rates of at least 1,000 K/sec, preferably above 1,000,000 K/sec, to block the continued growth of the nucleated particles and produce a nanosize powder suspension of narrow particle-size distribution. The nanopowder is then harvested by filtration from the quenched vapor stream and the carrier medium is purified, compressed and recycled for mixing with new precursor material in the feed stream.

Abstract: A method for preparing aluminium nitride includes a first step in which a mixture is formed of aluminium powder and ammonium halide powder. The mixture is then molded into a tablet, which is ignited in an airtight chamber containing nitrogen gas. Aluminium nitride is formed of the tablet through the combustion reaction of the tablet. The gas generated in the decomposition of the ammonium halide forms a number of channels in the tablet so as to enable nitrogen gas to enter the tablet to react with aluminium. The synthesis of aluminium nitride of high purity under low pressure is possible in view of the catalytic effect of the ammonium halide.

Abstract: The present invention provides a method for producing an aluminum nitride sintered body having excellent characteristics and an aluminum nitride powder conveniently and inexpensively. The present invention relates to a method for production of an aluminum nitride sintered body comprising forming a metal aluminum power into a thin-plate like shape, heating the formed body to a temperature not exceeding the melting point of aluminum in a vacuum atmosphere, and then sintering it under N.sub.2 pressure (1-150 kg/cm.sup.2), and a method for production of an aluminum nitride powder comprising heating a metal aluminum powder to a temperature not exceeding the melting point of aluminum in a vacuum atmosphere, sintering it under N.sub.2 pressure (1-150 kg/cm.sup.2, and further cooling and pulverizing it.

Abstract: Disclosed is a method of manufacturing aluminum nitride, which comprises the steps of preparing a mixed gas consisting essentially of an ammonia gas and at least 0.5% by volume of a hydrocarbon gas, calcining .gamma.-Al.sub.2 O.sub.3 or a precursor thereof at 300.degree. to 1,100.degree. C. so as to prepare the .gamma.-Al.sub.2 O.sub.3 having a moisture content of 1 weight % or less; heating the calcined .gamma.-Al.sub.2 O.sub.3 in the mixed gas at a temperature of 1,200.degree. to 1,700.degree. C., thereby preparing porous aluminum nitride having a specific surface area of 10 m.sup.2 /g or more; and heat-treating the porous aluminum nitride in an atmosphere of an ammonia gas, or a mixed gas of an ammonia gas and an inert gas, at 1600.degree. to 2000.degree. C., so as to make contents of both carbon and oxygen contained in the aluminum nitride 1 weight % or less.

Abstract: A process for preparing silicon carbide fiber by the carbothermal reduction of silica fiber. In the first step of the process, a specified silica fiber is contacted with a source of elemental carbon to produce a reactant mass; the silica fiber is comprised of at least about 99.5 weight percent of silica, has a density of at least about 2.15 grams per cubic centimeter, has a diameter of from about 1 to about 100 microns and an aspect ratio of at least about 30. From about 3.2 to about 5.0 moles of carbon are present in the carbon source for each mole of the silica. The reactant mass is heated at a temperature of from about 1,400 degrees centigrade to about 2,300 degrees centigrade for at least about 0.5 hours.