抄録
The reduction process of NiO with hydrogen is divided into four steps with respect to the electrical resistance: (1) an initial increase in the electrical resistance up to a maximum, (2) a gradual decrease from the maximum, (3) an abrupt decrease, and (4) a successive decrease to a definite electrical resistance. In the initial increase, NiO reaches a stoichiometric composition. After completion of the stoichiometric composition, NiO is partly reduced to form islands of reduced Ni. At the third step, the islands spread throughout the surface of NiO to complete the conductive layer. Upon completion of the conductive layer, the electrical resistance decreases abruptly. The thickness of the conductive layer increases with an increase in the reducing time, which is responsible for the gradual decrease in the electrical resistance. Thermobalance having a sensitivity of 0.5mg detected no weight loss due to the hydrogen reduction of NiO at the first step.
