Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Temperature Driven Transformation of CsPbBr$_3$ Nanoplatelets into
  Mosaic Nanotiles in Solution through Self-Assembly   Two-dimensional colloidal halide perovskite nanocrystals are promising
materials for light emitting applications. In addition, they can be used as
components to create a variety of materials through physical and chemical
transformations. Recent studies focused on nanoplatelets that are able to
self-assemble and transform on solid substrates. Yet, the mechanism behind the
process and the atomic arrangement of their assemblies remain unclear. Here, we
present the transformation of self-assembled stacks of CsPbBr$_3$ nanoplatelets
in solution, capturing the different stages of the process by keeping the
solutions at room temperature and monitoring the nanocrystal morphology over a
period of a few months. Using ex-situ transmission electron microscopy and
surface analysis, we demonstrate that the transformation mechanism can be
understood as oriented attachment, proceeding through the following steps: i)
desorption of the ligands from the particles surfaces, causing the merging of
nanoplatelet stacks, which first form nanobelts; ii) merging of neighboring
nanobelts that form more extended nanoplates; and iii) attachment of nanobelts
and nanoplates, which create objects with an atomic structure that resemble a
mosaic made of broken nanotiles. We reveal that the starting nanoplatelets
merge seamlessly and defect-free on an atomic scale in small and thin
nanobelts. However, aged nanobelts and nanoplates, which are mainly stabilized
by amine/ammonium ions, link through a bilayer of CsBr. In this case, the
atomic columns of neighboring perovskite lattices shift by a half-unit-cell,
forming Ruddlesden-Popper planar faults.

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The categories of this paper are: astro-ph
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: stat