Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Study of intercalation and deintercalation of Na_xCoO_2 yH_2O single
  crystals   Single crystals of NaxCoO2 with beta-phase (x=0.55, 0.60 and 0.65),
alpha'-phase (x=0.75) and alpha-phase (x=0.9, 1.0) have been grown by the
floating zone technique. The Na-extraction and hydration were carried out for
the alpha'-sample to get superconducting phase of NaxCoO2.yH2O (x~0.3, y~1.3).
Hydrated single crystals exhibit cracked layers perpendicular to the c-axis due
to a large expansion when the water is inserted into the structure. A study of
intercalation/deintercalation was performed to determine the stability of the
hydrated phase and effects of hydration on the structure of the compound. X-ray
diffraction and Thermogravimetric experiments are used to monitor the process
of water molecules accommodated in and removed from the crystal lattice. The
initial intercalation process takes place with two-water molecules
corresponding to y=0.6) inserted in a formula unit, followed by a group of four
(y=1.3) to form a cluster of Na(H2O)4. Thermogravimetric analysis suggests that
the deintercalation occurs with the removal of the water molecules one by one
from the hydrated cluster at elevated temperatures of approximately 50, 100,
200 and 300 C, respectively. Our investigations reveal that the hydration
process is dynamic and that water molecule inter- and deintercalation follow
different reaction paths in an irreversible way.

29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math