| 摘要 |
<p>PURPOSE:To stabilize an electron emitting property, by providing a rare earth metal oxide layer of a prescribed thickness between a base and an electron emitting substance layer to disperse a composite oxide layer of a reducing element into the electron emitting substance layer. CONSTITUTION:A layer 12 made of a rare earth metal oxide such as Sc2O3 and having a thickness of 10mu or less and an electron emitting substance layer 2 whose main constituent is a Ba-containing alkaline earth metal oxide are sequentially provided on a base 1 made of nickel as the main constituent and containing a reducing element such as Si. With this constitution, the oxidation of the base 1 can be prevented at the time of activation in the making of the layer 2 and at the time of operation as a cathode. Besides, the diffusion of the reducing element out of the base 1 into the layer 2 is appropriately controlled to prevent a composite oxide layer of the reducing element from concentrating on and near the boundary of the base 1 and the layer 2. This results in stabilizing an electron emitting property for a long period of time.</p> |
