GrapheneGraphene

MATERIALS SCIENCEMATERIALS SCIENCE&&

ENGINEERING ENGINEERING

Anandh Subramaniam & Kantesh Balani

Materials Science and Engineering (MSE)

Indian Institute of Technology, Kanpur- 208016

Email: anandh@iitk.ac.in, URL: home.iitk.ac.in/~anandh

AN INTRODUCTORY E-BOOKAN INTRODUCTORY E-BOOK

Part of

http://home.iitk.ac.in/~anandh/E-book.htmhttp://home.iitk.ac.in/~anandh/E-book.htm

A Learner’s GuideA Learner’s GuideA Learner’s GuideA Learner’s Guide

Carbon is perhaps the most fascinating element in nature The principal forms of carbon are:

Graphite Diamond Fullerene, nanotubes and related structures

Graphene

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

Crystal = Lattice + Motif

Grey atoms sit on the lattice positions

Motif = 1 grey + 1 green(in positions as shown)

Structure of single graphene sheet

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