Comment on 'New Clues to the Local Atomic Structure of Short-Range Ordered Ferric Arsenate from Extended X-ray Absorption Fine Structure Spectroscopy'

摘要

Mikutta, Mandaliev, and Kretzschmar claimed that ferric arsenate, estimated to be ~1 nm in size,2 has a scorodite-type local structure (framework model) instead of short chains of corner-linked FeO_6 octahedra with arsenate bridging adjacent octahedral corners as proposed by Paktunc et al. and Paktunc (chain model). The argument of Mikutta et al., based on As- and Fe-EXAFS spectra collected from two precipitates, suffers from a number of serious shortcomings in the analysis and interpretation of the EXAFS spectra.