Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconductivity in sintered-polycristalline
  PrBa$_{2}$Cu$_{3}$O$_{7-\delta}$   Superconductivity in thin films and powders, and in single crystals of Pr-123
has been found by Blackstead et al. and Zou et al., respectively. Nevertheless,
up to now it has never been reported in sintered-policrystalline samples. We
have prepared high-quality samples of this material by following a sol-gel
method.
  We characterized the structure of all samples by using XRD and SEM-EDS
techniques. Magnetic characterization was performed by measuring the
magnetization as a function of the temperature T, and the applied magnetic
field H. Measurements were taken in the ranges 2 K <T < 400 K and 0 <H< 5
Tesla. In this work we report by the first time superconductivity in Pr-123
sintered-polycristalline samples, with $T{_c}$ around 90 K, and $H{_c1}$ around
870 Oe.

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The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph