中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 14 No. 2 April 2004 |
RE2O3-Mo secondary emission material①
(1. The Key Laboratory of Advanced Functional Materials of Ministry of Education,
School of Materials Science and Engineering, Beijing Polytechnic University, Beijing 100022, China;2. Beijing Vacuum Electronics Research Institute, Beijing 100016, China)
Abstract:A durability test to determine anti-bombardment sensitivity of multi- RE2O3-Mo secondary emission material was carried out and the variation of maximum secondary emission coefficient (δmax) was monitored at regular intervals. After the experiment, the cathode was analyzed with SEM, EDS and XRD techniques. The results show thatδmaxof multi-RE2O3-Mo cermets cathode heated to 1 100℃under electron bombardment of 300 W/cm2reaches the peak of 3.35 at 200 h. After 500 h of bombardment, the maximum secondary-electron-yield curve stabilizes. Theδmaxvalue of the cathode remains at about 2.5 after 1 000 h and represents a good anti-bombardment property. The highδmaxvalue of the cathode is related with formation of an enriched Y2O3layer on the surface under high temperature and with the amount ofLa2O3 particles in the shape of nanometer distributed on the surface. Under the experimental conditions, the drop ofδmax value may be caused by the reduction of La2O3content and the porous layer resulted from evaporation of MoO2, which is formed when Mo at the surface is oxidized.
Key words: rare earth oxide; molybdenum; anti-electron-bombardment property; secondary emission