Graphene crystal
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Graphene
Part of
MATERIALS SCIENCE
& A Learner’s Guide
ENGINEERING
AN INTRODUCTORY E-BOOK
Anandh Subramaniam & Kantesh Balani
Materials Science and Engineering (MSE)
Indian Institute of Technology, Kanpur- 208016
Email: [email protected], URL: home.iitk.ac.in/~anandh
http://home.iitk.ac.in/~anandh/E-book.htm
Graphene
Carbon is perhaps the most fascinating element in nature
The principal forms of carbon are:
Graphite
Diamond
Fullerene, nanotubes and related structures
A single sheet of graphite is called graphene
It is sp2 hybridized covalently bonded
The bonding between the graphene sheets in graphite is of van der Walls type
In this set of slides we consider crystallographic concepts related to graphene
It is a hexagonal array of Carbon atoms, which is NOT a lattice
Part of the hexagonal array of C atoms which forms
the Graphene structure
Not all carbon positions
form a lattice
As atoms A & B do not
have identical surrounding
both cannot be lattice
points
Structure of single graphene sheet
Crystal = Lattice + Motif
Grey atoms sit on the
lattice positions
Motif = 1 grey + 1 green
(in positions as shown)
Either the green or the grey carbon atoms can
be considered to be located at lattice points
(but not both)
In plane motif consists of two C atoms
The unit cell is as marked