Influence of Aluminates Composition on Ba-W Cathode Characteristics: Influence of Aluminates Composition on Ba-W Cathode Characteristics

Precursor powder of 612 aluminates (n(BaO):n(CaO):n (Al sub(2)O sub(3))=6:1:2) was prepared by liquid phase co-precipitation method. In addition, the aluminates were prepared by calcinations of the precursor powder under different atmospheres (H sub(2), CO sub(2), N sub(2)) and temperatures (1300[degrees]C, 1400[degrees]C, 1500[degrees]C). The obtained products are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), TG-DTA and so on. Then effects of different aluminates on the emission properties of Ba-W cathode were systematically investigated. The results show that the crystalline phase of aluminates prepared under H sub(2) at 1500[degrees]C is Ba sub(5)CaAl sub(4)O sub(1 2), The Ba-W cathodes impregnated with this kind aluminates have the maximum emission current density (12.2 A/cm super(2)) and the minimum rate of evaporation (1.09x10 super(-8) g/(cm super(2)[middot]s)).