Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-pressure study of X-ray diffuse scattering in ferroelectric
  perovskites   We present a high-pressure x-ray diffuse scattering study of the ABO$_3$
ferroelectric perovskites BaTiO_3 and KNbO_3. The well-known diffuse lines are
observed in all the phases studied. In KNbO_3, we show that the lines are
present up to 21.8 GPa, with constant width and a slightly decreasing
intensity. At variance, the intensity of the diffuse lines observed in the
cubic phase of BaTiO_3 linearly decreases to zero at $\sim 11$ GPa. These
results are discussed with respect to x-ray absorption measurements, which
leads to the conclusion that the diffuse lines are only observed when the B
atom is off the center of the oxygen tetrahedron. The role of such disorder on
the ferroelectric instability of perovskites is discussed.

16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph