EVALUATION OF TEMPERATURE-DEPENDENT SURFACE-CHEMISTRY IN ZR2FE AND ZRVFE VIA X-RAY PHOTOEMISSION SPECTROSCOPY

The near atomic composition and the character of chemical bonds in two non-evaporable gettering alloys have been investigated via core level (Zr 3d; Fe 2p; V 2p; O 1s; C 1s) XPS (hv = 1253.6 eV). The samples ha ve been measured in UHV after in-air fracturing and various annealing steps (up to 850-degrees-C). For T > 400-degrees-C a progressive and s izeable decrease of the near surface C content along with an increase in the Zr concentration is observed in both alloys. An annealing-induc ed Zr enrichment at the surface is found, the metallic atomic concentr ations being permanently far from the nominal bulk stoichiometry. The annealing induces a strong evolution in the chemical bonds, the metall ic species being completely oxidized in-air fractured samples while pr ogressively emerging a metallic character at increasing temperatures. Surface metallization proceeds faster in Zr2Fe than in the V-containin g getter.