Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-temperature structural phase transition in multiferroic LiCu_2O_2   LiCu_2O_2 single crystals were studied in the temperature range 300-1100 K by
means of heating-cooling curves of differential thermal analysis (DTA),
thermogravimetry (TG), X-ray powder diffraction and electrical measurements. A
reversible first-order phase transition between orthorhombic and tetragonal
phases was found to take place at 993 K. At the transition, a peak is observed
in the DTA curves, as well as jumps of the unit cell parameters and electrical
resistivity. Considering the crystal structure of LiCu_2O_2 and the entropy
change associated with the phase transition, it is concluded that the phase
transition is related to processes of order-disorder of the Cu2+ and Li+
cations onto their crystallographic positions.

35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex