Chemistry Reference
In-Depth Information
The magnetization data given in the Fig. 14 are corrected for the
weight of adsorbed TTF. Magnetic hysteresis data at 300 K are shown as
insets. In the case of 0.05 M TTF-HG, magnetization data are shown at 1
T as an inset. Magnetization data of HG with adsorbed TCNE are similar
to those with TTF, except that the decrease in magnetization relative to
pure HG is smaller.
The value of M
S
at 300 K decreases on adsorption of TTF and
TCNE, the decrease being larger in the case of former. The Curie-Weiss
temperature, Θp, also decreases markedly on adsorption of these
molecules. Clearly, charge-transfer interaction between graphene and
TTF (TCNE) is responsible for affecting the magnetic properties.
8. INORGANIC GRAPHENE ANALOGUES
Following the discovery of fullerenes [67] in 1985, it was soon
recognized that inorganic layered materials such as MoS
2
and WS
2
can
also form fullerene-like structures [68-70]. After the discovery of carbon
nanotubes [71], inorganic nanotubes analogous to carbon nanotubes
were prepared and characterized, nanotubes of MoS
2
and WS
2
being
archetypal examples [72-75]. With the discovery and characterization of
graphene, the two dimensional nanocarbon, which has created great
sensation in last three to four years, it would seem natural to explore the
synthesis of graphene analogues of inorganic materials such as
dichalcogenides of molybdenum and tungsten which posses layered
structures [76]. We have been making efforts to prepare graphene-like
analogues of MoS
2
and WS
2
. There is an early report [77] on graphene-
like MoS
2
prepared by lithium intercalation and exfoliation, but the
material was characterized only by X-ray diffraction which is not
sufficient to determine the exact nature and number of layers. There have
been attempts to prepare single layers of WS
2
by lithium intercalation
and exfoliation as well [78-79] and here again the product was only
characterized on the basis of (002) reflection in the X-ray diffraction
pattern Since even few-layer MoS
2
and WS
2
containing five layers do
not exhibit the (002) reflection prominently, it is necessary that layered
MoS
2
and WS
2
produced by lithium intercalation and exfoliation are
