Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Structure and a Bond-Valence-Sum Study of the 1-2-3 Superconductors
  CLBLCO and YBCO   We present a study of the crystal structure of the 1-2-3 superconductor
[Ca(x)La(1-x)][Ba$(1.75-x)La(0.25+x)]Cu(3)O(y) (``CLBLCO''). Because of the
presence of both La and Ba ions in the ``Ba'' layer, the local symmetry of
YBa(2)Cu(3)O(y) (``YBCO'') is lost. One can no longer assume that an ``apical''
oxygen atom always lies strictly on the line joining CuI and CuII ions, and a
Pauling bond-valence calculation is very useful as an adjunct to the Rietveld
refinement of the positions of the La and Ba ions. When a Rietveld analysis is
performed allowing for the possibility that the apical oxygen atoms may be
slightly displaced along the a or b direction, the bond valence sums for both
La and Ba are close to the natural oxidation states of these ions.
  We have also used the bond-valence-sum method to study the mean oxidation
states of the CuI and CuII ions in both CLBLCO and YBCO. Our results for YBCO
differ from some previously published results. Our main conclusion is that,
while the method may be useful in finding the charge concentration on the CuII
plane, it definitely does not yield the concentration of mobile holes, nor the
concentration of superconducting charge carriers.

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The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin