Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of Mg substitution in Sr2SiO4:Eu2+ nanophosphors for blue and
  white emission at near UV excitation   Nanophosphors of (Sr0.98-xMgxEu0.02)2SiO4 (x=0, 0.18, 0.38, 0.58 and 0.78)
were prepared through low temperature solution combustion method and their
luminescence properties were studied. The emission peak for Eu2+ doped Sr2SiO4
nanophosphor is observed at ~490 nm and ~553 nm corresponding to two Sr2+ sites
Sr(I) and Sr(II) respectively for 395 nm excitation but the addition of Mg2+
dopant in Sr2SiO4 leads to suppression of ~553 nm emission peak due to absence
of energy levels of Sr (II) sites which results in a single broad emission at
~460nm. It was shown that the emission peak blue shifted with increase in Mg
concentration which may be attributed to change in crystal field environment
around Sr(I) sites. Therefore the (Mg0.78Sr0.20Eu0.02)2SiO4: Eu2+ nanophosphor
can be used for blue emission and the Sr2SiO4:Eu0.042+ for green-yellow
emission at 395 nm excitations. The CIE coordinates for mixed powders of
(Mg0.78Sr0.20Eu0.02)2SiO4 and Sr2SiO4:Eu0.042+ (in 1: 1 ratio) falls in the
white region demonstrating the possible use of the mixture in white light
generation using near UV excitation source.

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The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: q-fin