Effect of Sc2O3 addition on the phase composition and electron emission performance of Co-precipitated aluminates for impregnated cathodes. Issue 13 (1st July 2021) - Zheng, Qiang
Abstract: Herein, a series of 6BaO·1CaO·2Al2 O3 + x wt% Sc2 O3 ( x = 1, 3, 5, 7, 9) impregnants were synthesized by a liquid-phase co-precipitation method and subsequent sintering at 1200 °C. The as-synthesized emissive materials were impregnated into porous tungsten matrices at 1700 °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 Al2 O6, Ba2 ScAlO5, and BaAl2 O4 phases. Furthermore, the addition of 3 wt% Sc2 O3 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 Sc2 O3 content, which could be attributed to an increase in the concentration of non-active BaAl2 O4 phase in the impregnants.