Surface Properties of Etched Tungsten Single Crystals

An examination of the surface properties of chemically etched W single crystals has been made to determine the possibility of developing a macroscopic surface with adsorption properties equivalent to an ideal crystal plane.Crystals up to three inches in length have been grown in 0.003-inch W wires by a thermal gradient technique. The crystals completely filled the wire cross section.The etching appeared to have produced a surface which was homogeneous on a microscopic level. Thermionic emission was observed to be identical for the three crystallographic directions, [112], [112̄], and [110], with a value of φ₀*=5.25±0.05 v. Surface ionization measurements gave the same value of the work function within experimental error.