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Direct determination of electrical conductivity of oxide cathodes

机译:直接测定氧化物阴极的电导率

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The application range of oxide cathodes, e.g. in CRTs is limited by the critical dc current density (typically 1-3 A/cm(2)) and hence by the electrical Conduction mechanism. The electrical conductivity sigma(el) of the oxide layer has now been determined directly in a new procedure in a close-spaced planar diode configuration in an UHV chamber, together with thermionic emission data. The cathode temperature measured as a function of continuous dc load is essentially the result of a superposition of electron emission cooling-proportional to the dc current-and ohmic heating proportional to the square of the dc current. At the compensation point between electron emission cooling and ohmic heating, sigma(el) can be detennined directly from the emission data. After activation a result of about 10(-2) (Omegacm)(-1) at 780 degreesC true temperature is obtained for BaSr-oxide cathodes, which is consistent with literature. It is shown that electrical conductivity decreases with operating time in accordance with reduced Ba generation. a., can be increased by oxide dopants like yttria or europia. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 15]
机译:氧化物阴极的应用范围例如CRT中的电流受临界直流电流密度(通常为1-3 A / cm(2))限制,因此受电传导机制限制。氧化层的电导率σ(el)现在已经通过新程序直接在UHV室中以近距离平面二极管配置以及热电子发射数据确定。作为连续直流负载的函数而测得的阴极温度基本上是电子发射冷却与直流电流成正比,欧姆加热与直流电流的平方成正比的叠加结果。在电子发射冷却和欧姆加热之间的补偿点,可以直接从发射数据确定sigma(el)。活化后,在780摄氏度下,BaSr氧化物阴极的真实温度约为10(-2)(Ωcm)(-1),这与文献一致。结果表明,随着Ba生成量的减少,电导率随工作时间而降低。 a。可以通过氧化钇或氧化铀等氧化物掺杂剂增加。 (C)2002 Elsevier Science B.V.保留所有权利。 [参考:15]

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