Effect Of Sc2o3 Addition On The Phase Composition And Electron Emission Performance Of Co-Precipitated Aluminates For Impregnated Cathodes

Herein, a series of 6BaO center dot 1CaO center dot 2Al(2)O(3) + x wt% Sc2O3 (x = 1, 3, 5, 7, 9) impregnants were synthesized by a liquid-phase co-precipitation method and subsequent sintering at 1200 degrees C. The as-synthesized emissive materials were impregnated into porous tungsten matrices at 1700 degrees C, and their phase composition and electron emission performance were investigated. The X-ray diffraction analysis of the sintered and melted impregnated products revealed that they comprised multi-phase structures consisting of (Ba,Ca)(3)Al2O6, Ba2ScAlO5, and BaAl2O4 phases. Furthermore, the addition of 3 wt% Sc2O3 to the impregnated test cathodes significantly increased the emission level of the test cathode to 11.4 +/- 0.6 A cm(-2) at 1100. CB (i.e., brightness temperature). The relationship between the electron emission properties and phase concentration in the impregnants was analyzed, and the results revealed that the emission performance of the cathodes deteriorated with an increase in the Sc2O3 content, which could be attributed to an increase in the concentration of non-active BaAl2O4 phase in the impregnants.