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Correlation of the emission of SIMS cluster ions with composition and structure from the Al 2− x Cr x O 3 Mixed Oxide Series
Author(s) -
Reed Nicola M.,
Vickerman John C.
Publication year - 1992
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740190150
Subject(s) - chromium , chemistry , ion , mole fraction , oxide , analytical chemistry (journal) , cluster (spacecraft) , crystallography , inorganic chemistry , organic chemistry , chromatography , computer science , programming language
Abstract The Al 2− x Cr x O 3 mixed oxide series demonstrates that as the composition of the oxide is varied then the distribution of secondary ion clusters is also observed to change. A general model has been proposed to account for these variations in the formation of secondary cluster ions. It has been shown that at very low chromium concentrations (0–0.1 mole fraction Cr) the incorporation of chromium into the Al 2 O 3 lattice, forming a solid solution, results in an increase in the Al‐O bonding as manifested by the increase in the AlO + and AlO − species concurrent with the reduction in the Al 2 + and Al 2 O 2 + clusters. At increasing concentrations of Cr (0.1–0.4 mole fraction Cr) these appears to be an increase in the AlO and CrO bonding. This increase is thought to be due to the development of the localized CrCr bonding. This is shown by the increase in the AlO 2 − and the AlO 4 − clusters, whilst the influence of the localized bonding is demonstrated by the increased Cr 2 O + species. Ther is a decrease in any clusters containing both Al and Cr which is explained in terms of the preference of the chromium to be emitted as part of a chromium pair in this composition range. At further increased concentrations of Cr (0.4–1.0 mole fraction Cr) a chromium sub‐lattice begins to develop. This formation reduces the localized CrCr bonding which was noted at the lower chromium concentrations, which in turn results in a more delocalized bonding within the chromium lattice. This effect is indicated by the increase in the AlCrO x + species. The relative intensities of these cluster ions throughout the composition range, are also shown to reflect the changing oxidation state of the composite oxides across the series.