Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: In situ observation of phase separation and hierarchical microstructure
  of KxFe2-ySe2 single crystals   The nature of the phase separation in KxFe2-ySe2 single crystals is not well
understood. Here, temperature dependent SEM images provide compelling evidence
that phase separation corresponds to a nucleation and growth process rather
than a spinodal decomposition. The superconducting phase is the remnant of high
temperature phase after iron vacancy order-disorder transition. Three-dimension
(3D) spatial distribution of superconducting phase in the iron vacancy ordered
matrix was revealed by using focused ion beam scanning electron microscopy
(FIB-SEM). Our results clearly show that superconducting phase forms a
hierarchical structure. Understanding the formation of this hierarchical
structure not only can guide the synthesis of bulk superconductors in the
future, but also greatly enrich our knowledge about the interplay between phase
separation and solid-state phase transformations.

35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs