Evaluation of temperature‐dependent surface chemistry in Zr₂Fe and ZrVFe via X‐ray photoemission spectroscopy

Abstract

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; 0 1s; C 1s) XPS (hv = 1253.6 eV). The samples have been measured in UHV after in-air fracturing and various annealing steps (up to 850 "C). For T > 400 "C a progressive and sizeable decrease of the near surface C content along with an increase in the Zr concentration is observed in both alloys. An annealing-induced Zr enrichment at the surface is found, the metallic atomic concentrations being permanently far from the nominal bulk stoichiometry. The annealing induces a strong evolution in the chemical bonds, the metallic species being completely oxidized in-air fractured samples while progressively emerging a metallic character at increasing temperatures. Surface metallization proceeds faster in Zr,Fe than in the V-containing getter.

The characterisation of non-evaporable getters by Auger electron spectroscopy: analytical potential and artefacts

“…Surface analysis by electron spectroscopy allows to follow the variation of the surface composition during the NEG activation process. Both, AES and XPS have been used for various studies of bulk getters [2] [3] [4] [5] and also to monitor the activation of TiZrV NEG thin film coatings [6] [7].…”

Pumping characteristics of the St707 nonevaporable getter (Zr 70 V 24.6-Fe 5.4 wt %)

“…However a relevant difference has been observed when comparing the behaviour of NEG samples of different nature, i.e NEG strip (sintered powder) or alloy ingot. In the case of the strip the maximum Zr surface concentration is already obtained after heating at 500° C [19], whereas in the case of the ingot it increases more progressively up to the maximum temperature of 700° C reached in the experiment [20,21]. This difference has been attributed to a large concentration of crystallographic defects present in the powder, which provide easier diffusion paths for surface impurities and therefore allows removal of the passive layer at lower temperature.…”

“…Measurements of this type, carried out in various laboratories [16][17][18][19][20][21], indicate that a maximum Zr surface concentration of about 70% is achieved after 700° C heating. However a relevant difference has been observed when comparing the behaviour of NEG samples of different nature, i.e NEG strip (sintered powder) or alloy ingot.…”

Accelerators and Colliders

“…Available from: https://www.x-pmsp.com/i [Accessed: 02 January 2020] [17] Artun O. Calculation of productions of medical 201 Pb, 198 Au, 186 Re, 111 Ag, 103 Pd, 90 Y, 89 Sr, 77 Kr, 77 As, 67 Cu, 64 Cu, 47…”