Lanthanum hexaboride films were grown on tungsten and rhenium tips and foils by pulsed laser deposition. The X-ray diffraction spectra of the pulsed laser deposited LaB6 films on both substrates exhibited a crystalline nature with an average grain size of ∼125nm. Field emission studies of pointed and foil specimens were performed in conventional and planar diode configurations, respectively, under ultra-high vacuum conditions. An estimated current density of ∼ 1.2 x 104A/cm2 was drawn at an electric field of 3 x 103 and 6 x 103V/μm from the LaB6-coated tips of tungsten and rhenium, respectively. The Fowler-Nordheim plots were found to be linear, showing metallic behavior of the emitters. The field enhancement factors were calculated from the slopes of the Fowler-Nordheim plots, indicating that the field emission was from LaB6 nanoscale protrusions present on emitter surfaces. The emitters were operated for long-term current stability (3h) studies. The post-field emission surface morphology of the emitters showed no significant erosion of LaB6films during 3h of continuous operation. The observed behavior indicated that it was linked with the growth of LaB6 films on W and Re. These results revealed that the LaB6 films exhibited a high resistance to ion bombardment and excellent structural stability.

Field Emission Studies of Pulsed Laser Deposited LaB6 Films on W and Re. Late, D.J., More, M.A., Misra, P., Singh, B.N., Kukreja, L.M., Joag, D.S.: Ultramicroscopy, 2007, 107[9], 825-32