Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synthesis of nanocrystalline Spinel phase by Mechanical Milling of
  Al-Cu-Fe and Al-Cu-Cr-Fe Quasicrystalline alloys   In the present study, low-temperature synthesis of (Cu Fe)Al2O4 and (Cu Cr
Fe)Al2O4 spinels from the quasicrystalline phases was investigated with the
variation of process parameters during milling and annealing. The milling of
the quasicrystalline materials was carried out in an attritor mill at 400 rpm
for 40 hours with ball to powder ratio of 40:1 in hexane medium. Subsequently,
annealing was performed in an air ambience for 10, 20, and 40 h at 400, 500,
600 and 700 C in side a furnace in order to oxidize the mechanically milled
quasicrystalline phase for the possible formation of the spinel phase. It was
found that after annealing at higher temperature (500 C), mechanically milled
quasicrystalline alloy transformed to spinel phase whereas annealing at lower
temperature (500 C) it led to the formation of B2 phase as a major one along
with minor amount of oxide phase. The X-ray diffraction and transmission
electron microscopy of the annealed samples confirmed the formation of spinel
phase with an average grain size of 20-40 nm. It is interesting to note that
the nanospinel phases showed the different colors during various annealing time
and temperature. The optical properties of nanospinel materials, investigated
employing UV visible spectrometer exhibited absorption characteristics.

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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: physics
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The categories of this paper are: astro-ph