CARBON NANO TUBES AND THEIR APPLICATIONS PRESENTED BY SRI PRANJAL BARMAN DEPT. OF ELECTRONICS SCIENCE

INTRODUCTION CARBON NANOTUBE HAS AN INTENSE RESEARCH OVER WORLD BECAUSE OF THEIR PHYSICAL AND CHEMICAL PROPERTIES ARE MUCH MORE SIMILAR TO THE OTHER EARTH MATERIALS

UNIQUE ROLE OF CARBON IN NATURE CARBON PLAYS A UNIQUE ROLE IN NATURE THAT IS HAS THE CAPABILITY TO FORM DIFFERENT NETWORKS IS FUNDAMENTAL TO ORGANIC CHEMISTRY AND THE VERY BASIS FOR EXISTENCE OF LIFE

ALLOTROPES OF ELEMENTAL CARBON TWO DIMENTIONAL THREE DIMENTIONAL ONE DIMENTIONAL ZERO DIMENTIONAL

WHAT ARE CARBN NANO TUBES ? CNT ARE THE ONE DIMENTIONAL ALLOTROPES OF CARBON THEY ARE CYLINDRICAL STRUCTURE BASED ON HEXAGONAL LATTICE OF CARBON ATOMS DICOVERED BY DR. SUMIO LIJIMA AT NEC LABORATORY IN 1991 HAVING LENGTH TO DIAMETER RATIO EXCEEDS 10000

STRUCTURE THE CHEMICAL BONDING OF NANOTUBES ARE COMPOSED OF SP2 BOND CNTS NATURALLY ALIGN THEMSELVES INTO “ROPES” HELD TOGETHER BY “VAN DER WAAL’S” FORCE

ROLLING OF NANO TUBES CNTS CAN BE CONSIDERED AS ROLLED-UP GRAPHENE SHEETS WRAPPING OF GRAPHENE IS DETERMINED BY A PAIR OF INDICES (n,m)

METHODS OF ROLLING TWO ATOMS OF THE GRAPHENE SHEET ARE SELECTED AS THE ORIGIN DURING THE ROLLING THE TWO ATOMS ARE COINCIDE ROLL-UP VECTOR IS KNOWN AS CHIRAL VECTOR (Cn)

MAPS OF WRAPPING

ARMCHAIR ZIGZAG CHIRAL m = n m = 0

TYPES OF CNTS CARBON NANOTUBES ARE BROADLY CATAGORISED INTO TWO TYPES:- 1.SINGLE WALLED NANO TUBES 2.MULTI WALLED NANO TUBES

SINGLE WAL NANO TUBE SWNTS ARE CONCEPTUALIZED BY WRAPPING OF A SINGLE GRAPHENE SHEET

MULTIWAL NANO TUBE MWNTS CONSIST OF MULTIPLE LAYERS OF GRAPHENE SHEETS

SOME OF THE PROMINENT METHODS FOR CNT SYNTHESIS 1. CARBON ARC DISCHARGE 2. LASER-VAPORISATION TECHNIQUE 3. CHEMICAL VAPOUR DEPOSITION 4. ELECTROLYSIS

1.CARBON ARC DISCHARGE IT USES TWO ELECTRODES THROUGH WHICH DC IS PASSED IN AN INERT He ATMOSPHERE

2.LASER VAPORISATION IT USES CONDENSATION OF CARBON GENERATED FROM VAPORISATION OF GRAPHITE TARGETS.SWNTS ARE FORMED WHEN GRAPHITE CONTAINS CATALYSTS LIKE Ni,Cu,Pt ARE VAPOURISED BY LASER

3.CHEMICAL VAPOUR DEPOSITION CATALYTIC VAPOUR DECOMPOSITION IS DONE TO PRODUCE CARBON FIBERS

4.ELECTROLYSIS MWNTS ARE FORMED WHEN A CURRENT IS PASS THROUGH TWO GRAPHITE ELECTRODES IMMERSED IN MOLTEN IONIC SALTS AT 6000C

MECHANICAL PROPERTIES : CNTS ARE THE STRONGEST AND STIFFEST MATERIAL IN EARTH.THE YOUNG’S MODULUS IS 1 TERA PASCAL & ESTIMATED TENSILE STRENGTH IS 200 GIGA PASCAL

ELECTRICAL PROPERTIES FOR A GIVEN (n,m) CNTS EXHIBITES METALLIC OR SEMICONDUCTING PROPERTIES METALLIC NANO TUBES HAVE CURRENT DENSITY 1000 TIMES GREATER THAN METAL SUCH AS SILVER & COPPER

BAND STRUCTURE OF NANO TUBES IF THE VALUE OF (n – m) IS A MULTIPLE OF 3 THEN THE CNT IS METALLIC OTHERWISE THEY ARE SEMICONDUCTING BAND STRUCTURE OF NANO TUBES ALL ARMCHAIR (n = m) CNTs ARE METALLIC E Ef ARMCHAIR ZIGZAG

KINETIC PROPERTY MULTIPLE CONCENTRIC NANO TUBES EXHIBIT A STRIKING TELESCOPING PROPERTY WHEREBY AN INNER NANOTUBE CORE MAY SLIDE ALMOST WITHOUT FRICTION

THERMAL PROPERTY CNTS ARE EXPECTED TO BE VERY GOOD THERMAL CONDUCTOR ALONG THE TUBE CNTS WILL BE ABLE TO TRANSMIT UP TO 6000 WATTS PER METER PER KELVIN AT ROOM TEMPERATURE

APPLICATIONS MANY POTENTIAL APPLICATION HAS BEEN PROPOSED FOR CNTs.SOME OF THESE APPLICATIONS ARE NOW REALIZED IN PRODUCTS.OTHERS ARE DEMONSTRATED IN EARLY TO ADVANCED DEVICES.

CNT AS A CHEMICAL AND MECHANICAL SENSOR SINCE THE CNT’S ELECTRONIC PROPERTY IS A STRONG FUNCTION OF ITS ATOMIC STRUCTURE, MECHANICAL DEFORMATION AND CHEMICAL DOPING CAN INDUCE STRONG CHANGE IN CONDUCTANCE.SUCH CHANGES CAN BE EASILY DETECTED BY ELECTRON CURRENT SIGNAL

FIELD EMISSION HIGH ASPECT RATIO MAKES CNTS IDEAL EIELD EMISSION METARIAL SCANNING PROBE TIPS

DISPLAY LARGE REDUNDANCY HIGH VEDIO RATE HIGHER POWER EFFICIENCY WIDER OPERATING TEMPERATURE RANGE FED

SEMICONDUCTOR DEVICE CNTS ARE OUTSTANDING CANDIDATES FOR NOVEL ELCTRONICS DEVICES LIKE – CNT-FET;NANOELECTRONIC DEVICES ETC. CNT-FET

OTHER APPLICATIONS TODAY A LARGE NUMBER OF PRODUCTS USE CNT LIKE – X-RAY TUBE,Li-ION BATTERIES,VEHICLE FENDERS, GOLF CLUBS ETC. WEAVING THEM INTO CLOTHES TO CREATE SLAB AND BULLETPROOF COMPONENTS OF ELECTRICAL CIRCUIT DRUGS TRANSPORT INTO BODY MECHANICAL MEMORY AND NANO MOTORS

PROGRESS SO FAR MOTOROLA HAS DEVELOPED OF CNTs AT LOW TEMPERATURE. THEY HAVE GIVEN THE ABILITY TO DESIGN PRODUCTS AT MOLECULAR LAVEL TO ENHANCE SPECIFIC CHARACTERISTICS.

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