Abstract: An ammonia-producing catalyst includes a p-type semiconductor, an n-type semiconductor, and a metal fine particle having a function of adsorbing nitrogen. In the ammonia-producing catalyst including the metal fine particle, generation of ammonia is promoted, and the generated amount of ammonia is increased. An ammonia-producing catalyst includes a p-type semiconductor, an n-type semiconductor, and an ammonia-fixing compound for fixing ammonia. In the ammonia-producing catalyst including the ammonia-fixing compound, a fixed yield of ammonia is sufficiently increased.

Abstract: A method for preparing metal oxide particles having a primary particle size on the order of nanometers is provided. The method comprises subjecting a metal ion present in an aqueous solution and an amino alcohol to an initial stage of reaction with each other at normal temperatures under normal pressures for a given time, and adding at least once either of a metal ion or an amino alcohol or both thereof to the resulting reaction system for carrying out a subsequent stage of reaction for a given time wherein total amounts of the metal ion and the amino alcohol are such that the amino alcohol is used in the range of not less than a molar equivalent to the metal ion.

Abstract: A method for manufacturing alumina particles having a size on the order of nanometers and an excellent heat resistance at about 1000° C. comprises providing a liquid medium containing particles made of ?-alumina or boehmite alumina hydrate and a metal component such as La, Ba, Mg or the like, and thermally treated the alumina and the metal component in the liquid medium in a pressurized condition. The thermally treated particles are dried and sintered at a temperature of from 900° C. to lower than 1200° C. to provide alumina particles which has a metal aluminate crystal phase thereon. The metal component is formed as a solid solution as a surface layer of individual alumina particles by subjecting the alumina particles and the metal component to the thermal treatment prior to sintering, so that the metal aluminate crystal phase can be formed by sintering at temperatures lower than ordinary sintering temperatures.

Abstract: A method for preparing metal oxide particles having a primary particle size on the order of nanometers is provided. The method comprises subjecting a metal ion present in an aqueous solution and an amino alcohol to an initial stage of reaction with each other at normal temperatures under normal pressures for a given time, and adding at least once either of a metal ion or an amino alcohol or both thereof to the resulting reaction system for carrying out a subsequent stage of reaction for a given time wherein total amounts of the metal ion and the amino alcohol are such that the amino alcohol is used in the range of not less than a molar equivalent to the metal ion.