Publication Date:
2012-12-16
Description:
May 2013 Publication year: 2013 Source: Vacuum, Volume 91 The morphology of tungsten tip (microsized monocrystal) adsorbed with Pt at coverages up to around 2 ML and subsequently annealed at temperatures ranging from 1000 K to 2100 K was studied using Field Emission Microscopy (FEM) technique. The sharpening of the [111] pole region was manifested by significant increase of field emission current density. This effect was observed for Pt coverages ranging from 0.1 ML to 1.1 ML and full range of examined annealing temperatures, but was most pronounced for annealing at temperatures exceeding 1300 K. Formation of the sharp apex was accompanied by growth of {112} facets for the annealing temperatures lower than 1900 K. Annealing at higher temperatures resulted in formation of sharp apex of the W tip and complete disappearance of {112} planes when the Pt coverage exceeded approximately 0.25 ML. Highlights ► W tip covered by 0.1–1.1 ML of Pt and annealed forms a sharp apex at [111] pole. ► Best sharpening is observed for annealing at 1300 K–2100 K. ► For Pt coverages exceeding 1.1 ML no sharpening effect is observed. ► Annealing at T 〉 1900 K causes disappearing of {112} facets.
Print ISSN:
0042-207X
Electronic ISSN:
1879-2715
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
