Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Review of the recent x-ray and neutron powder diffraction studies on
  lead zirconate titanate   The issues related to the structure refinement of Pb(ZrxTi1-x)O3 (PZT) solid
solutions are discussed. Particular attention is paid on the modelling of the
co-existing phases in the vicinity of the morphotropic phase boundary (MPB),
where local symmetry is often significantly lower than the average symmetry.
According to recent studies, two-phase co-existence in the vicinity of the MPB
is a thermodynamical necessity. Significantly different structural models for
PZT with $x$ in the vicinity of the MPB have recently been published.
Structural models, based on x-ray, neutron and electron diffraction studies,
are reviewed and two essentially different approaches were identified: (i) a
method where space group symmetry was decreased untill the features due to the
local distortions were 'modelled' and (ii) a method where the highest space
group symmetry compatible with the powder diffraction data was used together
with a model for a local disorder. Related to the method (ii), the essential
features of a model taking the hkl-dependent line broadening into account are
summarized. The underlying theme is to consider how local regions, with
symmetry lower than the average symmetry, should be modelled. Method (i) often
introduces unjustified structural parameters and should be avoided. By studying
the temperature and composition dependence of the structural parameters,
including line shape parameters and phase fractions in the case of the two
phase samples, one can further test the proposed models. The significance of
the local structure for electrical properties (switchable polarization and
electrical conductivity) is discussed by considering the local Pb ion
displacements and their dependence on the neighbouring B-cation configuration.

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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
5
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: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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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: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys