Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ternary Semiconductors NiZrSn and CoZrBi with half-Heusler structure: a
  first-principles study   The ternary semiconductors NiZrSn and CoZrBi with C1_b crystal structure are
introduced by calculating their basic structural, electronic and phononic
properties using density functional theory. Both the gradient-corrected PBE
functional and the hybrid functional HSE06 are employed. While NiZrSn is found
to be a small-band-gap semiconductor (E_g = 0.46 eV in PBE and 0.60 eV in
HSE06), CoZrBi has a band gap of 1.01 eV in PBE (1.34 eV in HSE06). Moreover,
effective masses and deformation potentials are reported. In both materials
ABC, the intrinsic point defects introduced by species A (Ni or Co) are
calculated. The Co-induced defects in CoZrBi are found to have a higher
formation energy compared to Ni-induced defects in NiZrSn. The interstitial Ni
atom (Ni_i ) as well as the V_Ni Ni_i complex introduce defect states in the
band gap, whereas the Ni vacancy (V_Ni) only reduces the size of the band gap.
Motivated by the reported use of NiZrSn for thermoelectric applications, the
Seebeck coefficient of both materials is calculated. We find that CoZrBi
displays a rather large thermopower of up to 500 micro-V/K when p-doped,
whereas NiZrSn possesses its maximum thermopower in the n-type regime. The
reported difficulties in achieving p-type doping in NiZrSn could be
rationalized by the unintended formation of Ni_i^2+ in conjunction with
extrinsic acceptors, resulting in their compensation. Moreover, it is found
that all types of defects considered, when present in concentrations as large
as 3%, tend to reduce the thermopower compared to ideal bulk crystals at
T=600K. For NiZrSn, the calculated thermodynamic data suggest that additional
Ni impurities could be removed by annealing, leading to precipitation of a
metallic Ni_2ZrSn phase.

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The categories of this paper are: cs
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn