Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Steric quenching of the switchable mirror effect Phys. Rev. B 75, 104109
  (2007)   Scandium was substituted for yttrium to observe the effect of unit cell size
on the optical metal-to-insulator (MIT) transition in the Y_(1-z)Sc_(z)H_(x)
alloy system. The optical transmittance decreases significantly for z>0.10.
Simultaneous electrical resistivity measurements confirm the transition from
trihydride to dihydride behavior with increasing z. These observations imply a
quenching of the MIT when the unit cell volume falls below a critical level
that is consistent with the boundary between trihydride and non-trihydride
forming rare-earth elements. A combinatoric model reveals this formation
boundary corresponds to two or more Sc per unit cell.

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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
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The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex