Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The valence state of iron in the Sr2Fe(Mo,W,Ta)O6.0 double-perovskite
  system: An Fe K-edge and L2,3-edge XANES study   Here we employ both Fe K and L2,3 edge x-ray absorption near-edge structure
(XANES) spectroscopy techniques to clarify that iron in the B-site ordered
double-perovskite halfmetal, Sr2FeMoO6.0, possesses a mixed-valence state,
FeII/III, and accordingly molybdenum a mixed MoV/VI valence state. A reliable
interpretation of the spectral features has been made possible by using a
series of samples of the Sr2Fe(Mo,W/Ta)O6.0 system. Replacing MoV/VI gradually
with WVI causes increasing amount of Fe to adopt the FeII state, whereas TaV
substitution shifts the valence of iron towards FeIII. As the valence of Fe
increases from II to III in the Sr2Fe(Mo,W/Ta)O6.0 system, the absorption
energy at the Fe K-edge gradually shifts towards the higher energy side.
Similarly, in the L2,3-edge XANES spectra intermediate spectral features are
revealed for the Sr2FeMoO6.0 sample in comparison with those for samples
heavily substituted with either W or Ta.

30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci