Electron-beam growing and purification of W crystals

High-purity W single crystals have been grown by the electron-beam floating zone melting technique. The structural quality of these crystals was subsequently improved by the application of a strain-annealing technique. X-ray diffraction methods revealed a near-perfect crystallographic structure. Well-ordered clean W surfaces free from all contaminants were obtained by a two-step heating procedure. Low-energy ion scattering and Auger electron spectroscopy confirmed that the cleaning procedures removed all impurities and that the crystal faces expose only W in the outermost atomic layers. Thin layers of Re were deposited on a W(110) single crystal by magnetron sputtering and investigated by ion scattering and Auger electron spectroscopy.