Abstract: A method of producing a silicon carbide powder comprising sintering a mixture containing at least a silicon source and a carbon source wherein the carbon source is a xylene-based resin. Preferable are an embodiment in which the above-mentioned silicon source is an alkoxysilane compound, an embodiment in which the above-mentioned alkoxysilane compound is selected from an ethoxysilane oligomer and an ethoxysilane polymer, an embodiment in which the above-mentioned mixture is obtained by adding an acid to a silicon source, then, by adding a carbon source, and other embodiments. A silicon carbide powder produced by the above-mentioned method of producing a silicon carbide powder wherein the nitrogen content is 100 ppm or less is preferable. A sintered silicon carbide obtained by sintering the above-mentioned silicon carbide powder wherein the volume resistivity is 1×100 &OHgr;·cm or more.

Abstract: The invention provides additives capable of fabricating a battery having an excellent combustion inhibiting effect, a low interfacial resistance of an electrolyte and excellent low-temperature discharging property and high-temperature storing property by adding to the electrolyte for the battery to maintain properties required as the battery and capable of fabricating an electrolyte electric double-layered capacitor having an excellent combustion inhibiting effect, a low interfacial resistance of an electrolyte and an excellent low-temperature discharging property by adding to the electrolyte for the electric double-layered capacitor to maintain sufficient electric properties such as electric conductivity and the like as well as a battery and an electric double-layered capacitor.

Abstract: A method of producing a silicon carbide powder comprising sintering a mixture containing at least a silicon source and a carbon source wherein the carbon source is a xylene-based resin. Preferable are an embodiment in which the above-mentioned silicon source is an alkoxysilane compound, an embodiment in which the above-mentioned alkoxysilane compound is selected from an ethoxysilane oligomer and an ethoxysilane polymer, an embodiment in which the above-mentioned mixture is obtained by adding an acid to a silicon source, then, by adding a carbon source, and other embodiments. A silicon carbide powder produced by the above-mentioned method of producing a silicon carbide powder wherein the nitrogen content is 100 ppm or less is preferable. A sintered silicon carbide obtained by sintering the above-mentioned silicon carbide powder wherein the volume resistivity is 1×100 &OHgr;·cm or more.

Abstract: The present invention provides an additive for a non-aqueous electrolytic solution including a phosphazene derivative which is solid at 25° C.

Abstract: The present invention provides an additive which is able to make a non-aqueous-electrolyte secondary cell or a non-aqueous electrolyte electric double layer capacitor which is excellent in low-temperature characteristics, while maintaining a necessary cell properties, and a non-aqueous-electrolyte secondary cell or a non-aqueous electrolyte electric double layer capacitor that contains therein the additive.

Abstract: The present invention provides additives for a non-aqueous electrolytic solution secondary cell and a non-aqueous electrolytic solution electric double layer capacitor comprising a phosphazene derivative represented by formula (1):

Abstract: The present invention provides an additive for a non-aqueous electrolyte comprising a phosphazene derivative represented by the following formula (1):

Abstract: A highly safe non-aqueous electrolyte secondary cell with excellent self-extinguishing property or flame retardancy is provided which comprises an anode, a cathode, a non-aqueous electrolyte in which an Li-salt as a supporting salt is dissolved in an organic solvent, and a separator. When a high crystalline carbon material such as graphite is used as cathode active substances, it is possible to provide a non-aqueous electrolyte secondary cell whose charging/discharging life is lengthened, whose interface resistance at the non-aqueous electrolyte can be reduced, and which has excellent discharging characteristics at low temperature.

Abstract: A long-lived cleaning vessel for ultrasonic cleaning is provided which is easily manufactured and is also easy to handle due to a simple structure thereof, and has excellent durability, mechanical strength, and corrosion resistance. A cleaning vessel 1 of the present invention includes a layer of silicon carbide sintered body 3 which propagates ultrasonic waves. Further, a silicon carbide sintered body is provided which can be applied to components for semiconductor production apparatuses, components for electronic information equipment, and various structural components for vacuum devices and the like, and which can particularly suitably be used as an ultrasonic resonance plate or an ultrasonic diaphragm, and can be easily processed, and further which can be made thinner while maintaining sufficient mechanical strength. The silicon carbide sintered body can propagate ultrasonic waves and an acoustic velocity of ultrasonic waves propagated therethrough is 4000 to 20000 m/s.

Abstract: A long-lived cleaning vessel for ultrasonic cleaning is provided which is easily manufactured and is also easy to handle due to a simple structure thereof, and has excellent durability, mechanical strength, and corrosion resistance. A cleaning vessel 1 of the present invention includes a layer of silicon carbide sintered body 3 which propagates ultrasonic waves. Further, a silicon carbide sintered body is provided which can be applied to components for semiconductor production apparatuses, components for electronic information equipment, and various structural components for vacuum devices and the like, and which can particularly suitably be used as an ultrasonic resonance plate or an ultrasonic diaphragm, and can be easily processed, and further which can be made thinner while maintaining sufficient mechanical strength. The silicon carbide sintered body can propagate ultrasonic waves and an acoustic velocity of ultrasonic waves propagated therethrough is 4000 to 20000 m/s.

Abstract: A silicon carbide single crystal which can be suitably used as a semi-insulating or insulating single crystal substrate and the like, and a method of efficiently producing the same, are provided.

Abstract: A method of producing a silicon carbide powder comprising sintering a mixture containing at least a silicon source and a carbon source wherein the carbon source is a xylene-based resin. Preferable are an embodiment in which the above-mentioned silicon source is an alkoxysilane compound, an embodiment in which the above-mentioned alkoxysilane compound is selected from an ethoxysilane oligomer and an ethoxysilane polymer, an embodiment in which the above-mentioned mixture is obtained by adding an acid to a silicon source, then, by adding a carbon source, and other embodiments. A silicon carbide powder produced by the above-mentioned method of producing a silicon carbide powder wherein the nitrogen content is 100 ppm or less is preferable. A sintered silicon carbide obtained by sintering the above-mentioned silicon carbide powder wherein the volume resistivity is 1×100 &OHgr;· cm or more.

Abstract: A non-aqueous electrolyte electric double-layer capacitor in which there is no danger of being ignited, bursting or catching flame at the time of a short-circuit, has low internal resistance, superior properties at low temperatures, and is self-extinguishable or incombustible. In a first aspect, a non-aqueous electrolyte includes a non-aqueous electrolyte having a phosphazene derivative. In a second aspect, a potential window of the phosphazene derivative is a range having a lower limit of +0.5 or lower and an upper limit of +4.5 or higher, and a potential window of the organic solvent has a wider range than the potential window of the phosphazene derivative. In a third aspect, a conductivity of a quaternary ammonium salt solution (0.5 mol/l) is 2.0 mS/cm. In a fourth aspect, a permittivity thereof at a temperature of 25° C. is 15 or higher and a viscosity thereof is 20 mPa·s (20 cP) or lower.

Abstract: A non-aqueous electrolyte electric double-layer capacitor which has superior resistance to deterioration and superior properties at low temperatures while maintaining electrical characteristics such as sufficient electric conductivity and the like, and a non-aqueous electrolyte of the capacitor has low surface resistance. A first aspect of the non-aqueous electrolyte electric double-layer capacitor has a positive electrode, a negative electrode and a non-aqueous electrolyte which contains at least 2% by volume to less than 20% by volume of phosphazene derivative and a supporting electrolyte. A second aspect thereof has the positive electrode, the negative electrode and the non-aqueous electrolyte which contains at least 20% by volume of phosphazene derivative and the supporting electrolyte.

Abstract: A sintered silicon carbide has a high density and only small amounts of organic and inorganic impurities on the surface and in the vicinity of the surface, i.e., a density of 2.9 g/cm2 or more and an amount of each impurity smaller than 1.0×1011 atoms/cm2 on the surface and in the vicinity of the surface. A method for cleaning sintered silicon carbide in a wet condition comprises treating sintered silicon carbide in a step of dipping into a quasi-aqueous organic solvent, a step of dipping into an aqueous solution of an ammonium compound, a step of dipping into an aqueous solution of an inorganic acid and a step of dipping into pure water. Organic and inorganic impurities present on the surface and in the vicinity of the surface of the sintered silicon carbide are removed easily in accordance with the method.

Abstract: A method of wet-cleaning a sintered silicon carbide to remove, easily and within a short period of time, organic and inorganic impurities present on a surface and in a vicinity of the surface of the sintered silicon carbide. The method includes steps of: dipping the sintered silicon carbide into a quasi-aqueous organic solvent; and dipping the sintered silicon carbide into an aqueous solution of an inorganic acid, wherein at least one of the steps is conducted while ultrasonic waves are applied.

Abstract: A sintered silicon carbide has a high density and only small amounts of organic and inorganic impurities on the surface and in the vicinity of the surface, i.e., a density of 2.9 g/cm2 or more and an amount of each impurity smaller than 1.0×1011 atoms/cm2 on the surface and in the vicinity of the surface. A method for cleaning sintered silicon carbide in a wet condition comprises treating sintered silicon carbide in a step of dipping into a quasi-aqueous organic solvent, a step of dipping into an aqueous solution of an ammonium compound, a step of dipping into an aqueous solution of an inorganic acid and a step of dipping into pure water. Organic and inorganic impurities present on the surface and in the vicinity of the surface of the sintered silicon carbide are removed easily in accordance with the method.

Abstract: A long-lived cleaning vessel for ultrasonic cleaning is provided which is easily manufactured and is also easy to handle due to a simple structure thereof, and has excellent durability, mechanical strength, and corrosion resistance. A cleaning vessel 1 of the present invention includes a layer of silicon carbide sintered body 3 which propagates ultrasonic waves. Further, a silicon carbide sintered body is provided which can be applied to components for semiconductor production apparatuses, components for electronic information equipment, and various structural components for vacuum devices and the like, and which can particularly suitably be used as an ultrasonic resonance plate or an ultrasonic diaphragm, and can be easily processed, and further which can be made thinner while maintaining sufficient mechanical strength. The silicon carbide sintered body can propagate ultrasonic waves and an acoustic velocity of ultrasonic waves propagated therethrough is 4000 to 20000 m/s.

Abstract: A product holder that does not cause a product to become cracked or contaminated at the time of being conveyed and transported, subjected to a sputtering treatment, or the like, can be detected by an infrared ray detector, is superior in its strength, durability, chemical resistance, and the like, and is easily handled is disclosed. This product holder for holding a product having opposite end surfaces and is composed of a silicon carbide sintered body having a product accommodating portion, which accommodates and holds the product such that one end surface of the product is exposed, wherein a groove portion is formed in the product accommodating portion at a position which abuts the other end surface of the product, which opposes the one end surface.

Abstract: A sintered silicon carbide containing nitrogen is obtained by sintering a mixture of a powder of silicon carbide and a nonmetallic auxiliary sintering agent. The sintered silicon carbide has a density of 2.9 g/cm3 or more and contains 150 ppm or more of nitrogen. The sintered silicon carbide preferably has a volume resistivity of 1 &OHgr;·cm or less and contains &bgr;-silicon carbide in an amount of 70% or more of total silicon carbide components. Nitrogen can be introduced into the sintered silicon carbide by adding a nitrogen source, for example, an amine such as hexamethylenetetramine, ammonia, and triethylamine in the production of the powder of silicon carbide which is used as the material powder for producing the sintered silicon carbide or by adding the nitrogen source in combination with the nonmetallic auxiliary sintering agent in the production of the sintered silicon carbide.