Development of Nanocrystalline LaB₆ Electron Emitters Processed Using Arc Thermal Plasma Route

Present article discusses the role of plasma parameters on the morphology of nanocrystalline powders of lanthanum hexaboride (LaB ₆ ) synthesized by arc plasma gas-phase condensation method. The nanocrystalline powders so obtained were used to fabricate pellet-shaped cathodes of 5 mm diameter and thickness of 1 mm. Moreover, thermal plasma plume was used for sintering the cathodes and achieve desired densification. Prior to fabrication of cathodes, the synthesized powders of LaB ₆ were characterized using X-ray diffraction, Raman spectroscopy, and transmission electron microscopy to investigate phase purity and morphological properties. Finally, an indigenously developed thermionic emission experimental set-up was used to record thermionic emission current obtained from LaB ₆ cathode at different temperatures. Richardson Dushman equation was used to find out the work function of the cathode under investigation.