Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Crystal Structure and Elementary Properties of NaxCoO2 (x = 0.32, 0.5,
  0.6, 0.75, and 0.92) in the Three-Layer NaCoO2 Family   The crystal structures of the NaxCoO2 phases based on three-layer NaCoO2,
with x=0.32, x=0.51, x=0.60, x=0.75 and x=0.92, determined by powder neutron
diffraction, are reported. The structures have triangular CoO2 layers
interleaved by sodium ions, and evolve with variation in Na content in a more
complex way than has been observed in the two-layer NaxCoO2 system. The highest
and lowest Na containing phases studied (x=0.92 and x=0.32) are trigonal, with
three CoO2 layers per cell and octahedral Na ion coordination. The intermediate
compositions have monoclinic structures. The x=0.75 compound has one CoO2 layer
per cell, with Na in octahedral coordination and an incommensurate
superlattice. The x=0.6 and x=0.5 phases are also single-layer, but the Na is
found in trigonal prismatic coordination. The magnetic behavior of the phases
is similar to that observed in the two-layer system. Both the susceptibility
and the electronic contribution to the specific heat are largest for x=0.6.

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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: astro-ph
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: chao-dyn