| 摘要 |
PURPOSE:To heighten Q value remarkably in a microwave range and stably manufacture porcelain, being excellent in quantity productivity, and having fine characteristic. CONSTITUTION:After the mixture or the calcination of metallic oxide, which constitutes dielectric porcelain for microwave, such as La2O3-CaO-TiO2-MgO series, BaO-Nd2O3-TiO2 series, or the like, is molded, the molding is fired in 1250 deg.C-1700 deg.C in an oxidizing atmosphere. Thereafter, in a cooling process, a region, where the molding is gradually cooled at the rate of 5 deg.C/hr-200 deg.C/hr, is provided in a temperature range from a firing temperature to 500 deg.C, and a porcelain after firing is heat treated in the temperature range from the highest firing temperature to 500 deg.C in the oxidizing atmosphere, and oxygen hole density in the porcelain is desirably controlled so as to become 7X10<18> pieces/cm<3> or less. |
