Title: Preparation and characterisation of scandia doped dispenser cathodes

Authors: Jinshu Wang; Xi Wang; Wei Liu; Yuntao Cui; Yiman Wang; Meiling Zhou

Addresses: School of Material Science and Engineering, Beijing University of Technology, Number 100 Pingleyuan, Chaoyang District, Beijing, China. ' School of Material Science and Engineering, Beijing University of Technology, Number 100 Pingleyuan, Chaoyang District, Beijing, China. ' School of Material Science and Engineering, Beijing University of Technology, Number 100 Pingleyuan, Chaoyang District, Beijing, China. ' School of Material Science and Engineering, Beijing University of Technology, Number 100 Pingleyuan, Chaoyang District, Beijing, China. ' School of Material Science and Engineering, Beijing University of Technology, Number 100 Pingleyuan, Chaoyang District, Beijing, China. ' School of Material Science and Engineering, Beijing University of Technology, Number 100 Pingleyuan, Chaoyang District, Beijing, China

Abstract: Scandia doped dispenser cathodes were prepared by powder metallurgy method using mixed powder of scandia doped tungsten, barium-calcium aluminates obtained by sol-gel method. The scanning electron microscope observation results indicate that the cathode has submicron quasi-spherical tungsten grains structure with homogeneous distribution of Sc2O3 and barium-calcium aluminates which dispersed over and among W grains. The cathode exhibits good emission property, i.e. the current density of this cathode can reach more than 40A/cm² at 850°Cb. The cathode has low work function of 1.43 eV. Active substance of Sc, Ba and O diffuse from the inner part of cathode to the surface to form a Ba-Sc-O multilayer having certain ratios of Ba:Sc:O which contains much more Ba than normal dispenser cathode at the surface of Sc2O3-W matrix cathode during the activation period. This active-multi-layer is considered to be responsible for copious emission capability.

Keywords: scandia doping; tungsten matrix; dispenser cathodes; emission properties; Ba-Sc-O multilayer; powder metallurgy; nanotechnology; barium calcium aluminates; sol-gel.

DOI: 10.1504/IJNT.2013.050887

International Journal of Nanotechnology, 2013 Vol.10 No.1/2, pp.108 - 118

Available online: 07 Dec 2012 *

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