| 摘要 |
PURPOSE:To obtain the title superconducting material with small difference between its onset and offset temperatures, by contact reaction between an aqueous ammonia solution and metallic copper under pressure to produce cupric oxide powder consisting of specific lamellar crystal. CONSTITUTION:(A) Ammonia water or an aqueous solution comprising ammonia water and a water-soluble alkali metal hydroxide and (B) metallic copper are put to contact reaction with each other to obtain the objective high-temperature superconducting material constituted of cupric oxide powder consisting of lamellar crystal >=1mu in thickness on average with a specific surface area of <=5m<2>/g and mean size of 5-20mum. For the above reaction temperature, between 100 and 250 deg.C, the higher the temperature, the larger the crystal to be obtained and the further smaller the specific surface area. But, extremely raising the reaction temperature increases the partial pressure of water vapor, resulting in requiring expensive apparatuses and/or devices such as pressure vessel or seals, thus being impracticable. In the case of the reaction temperature between 100 and 250 deg.C, it is preferable that the partial pressure of oxygen be >=1.5kg/cm<2> (esp. 1.5-5.0kg/cm<2>). |
