| 摘要 |
PURPOSE:To obtain a gas detecting element which reduces considerably the time up to a stable operation by executing a process for forming a metallic oxide semiconductor by decomposing thermally an org. metallic compd. in an atmosphere under specific relative humidity or above thereby accelerating crystallization. CONSTITUTION:For example, an n-butanol soln. of tin 2-ethyl hexanoate is coated over the outside circumferential surface of an insulator base body 1 and is dired and heated to cover the entire surface including electrodes 2a, 2b fixed to the outside circumferential surface of the base body. Such base body 1 is placed on a jig studded with pins 6 around an insulating disk 5 and the electrodes 2a, 2b and the pins 6 are connected by means of lead wires 7. A heater 8 is assembled so as to be passed to the axial center part of the body 1. Such jig is inserted into a tubular furnace and steam kept under >=90% relative humidity is supplied into the furnace. The atmosphere is maintained at 80 deg.C and the surface of the body 1 is maintained by the heater at 500 deg.C to convert the surface on the outside circumferential surface of the body 1 to a thin semiconductor film 3 consisting of SnO2. A W-Cu-Al2O3 catalyst is stuck by an inorg. binder onto the film 3 to form a catalyst layer 4. The time up to the stable operation is thus reduced by about one tenth the time of the conventional element. |
