Ordered surface-alloys formation in the Zr/W(1 0 0) adsorption system

• Ultrathin Zr films on W(1 0 0) assemble in isomorphic with the substrate layers.
• Above 1700 K intermixing results in two ordered surface alloys formation.
• Stoichiometry and atomic structure of the alloys have been identified.
• Zr4W alloy transforms into Zr3W when the Zr film is dissolved in the substrate.

The Zr/W(1 0 0) adsorption system was examined in situ, applying STM, LEED and AES techniques. Zr mono-layers of average thickness 1.7–2.0, vapor-deposited under UHV on W(1 0 0) surface, were gradually annealed from 1200 to 2100 K. Up to 1700 K Zr layers were isomorphic with the substrate. Two surface superstructures of W(1 0 0) –(5×5)R26.6 and W(1 0 0)−c(2 × 4) were identified one at the temperature range 1700–2000 K, the other above 2000 K. The analysis of the experimental data combined with the ab initio structural calculations made it possible to ascribe the superstructures respectively to Zr4W and Zr3W ordered surface alloys.