NANO MATERIALS

Introduction and

synthesis

INTRODUCTION

In simple, any physical substance with structural dimensions between 1-100nm can be defined as

NANOMATERIAL

• Nano materials

“NANO” +”MATERIALS”

“dwarf”=quantum

WHAT ARE NANOMATERIALS?

WHAT ARE NANOMATERIALS?Nanomaterials:

Materials possessing one or more dimensional features having length of order of a billionth of a metre.

Simply ,1 inch = 2,54,00,000 nm. If one marble =1 nm,1 m would be size of earth.

WHY NANOMATERIALS ARE CALLED SO?

• NANOSCALE: Border line between macro scale and quantum scale.MACRO -------> NANO -------> QUANTUM

> 100nm 1-100nm < 1nm

IMPORTANCE AND PROPERTIES

1 nm = 1000 millionth of a metre. e.g.(1)Red blood cells = 7000 nm(approx.) (2)water molecule = 0.3 nm.At Nanoscale , the properties of materials can be

very different from those at larger scale.Such as (1)Optical (4) Melting (7)Bandgap (2)Catalysis (5) Conductivity (8)Surface area (3)Reactivity (6) Solubility (9)Mechanical properties

SIGNIFICANCEComposites made of nano particle become much stronger

than predicted. e.g. grain size (10 nm)is 7 times harder and tougher than

grain size (100 nm).The properties of materials can be differentat nanoscale

due to 2 main reason (1)Larger surface area chemically more reactive (2)Quantum effects begin to dominate the behaviour of matter at nano scale.

C L A S S I F I C AT I O N

APPEARANCE OF NANOMATERIALS

SYNTHESIS APPROACH OF NANOMATERIALS

TOP DOWN METHOD: From bulk materials to

nanomaterial.(MACRO to NANO scale)

BOTTOM UP METHOD: From quantum material to nano

material.(QUANTUM to NANO scale)

SYNTHESIS APPROACH OF NANOMATERIALS

TOP DOWN (BULK to NANO)

METHODS:1. MECHANICAL GRINDING: (a)larger scale materials are

grinded to nanoscale. 2. LITHOGRAPHY: (a)tiny chips from relatively large

structure.

BOTTOM UP (QUANTUM to NANO)

METHODS:1. SELF ASSEMBLY: (a) Desired Nanostructures are self

assembled without any external manipulation.

2. POSITIONAL ASSEMBLY: (a)We can program to manipulate

atom & molecule at will.

NANOMATERIALS SYNTHESIS TECHNIQUES

GAS PHASE METHODS: (1)Vapor Evaporation/Condensation (2)Chemical Vapor Deposition (3)Laser Ablation

CHEMICAL METHODS: (1)Precipitations (2)Micro-emulsion Synthesis (3)Sol gel Synthesis (4)Spray Drying/Spray Pyrolysis (5)Thermal Decomposition

MECHANICAL DEFORMATION: (1)Mechanical Alloying (2)Chemo - Mechanical Alloying (3)Severe Mechanical Deformation

DIFFERENCE BETWEEN TOP DOWN AND BOTTOM UP

APPROACHBottom – up Approach1. QUANTUM to NANO.

2. It can be found from nature.

3. Higher precision accuracy.

4. No wastage of material.

Top – down Approach1. BULK to NANO.

2. It cannot be found from nature.

3. Lower precision accuracy.

4. Wastage of material occurs.

ANSWER IS : “BOTTOM UP”

WHY?1. When object size is getting smaller in nanofabrication , bottom

– up approach is an increasingly important complement to top – down techniques.2. Bottom – up approach can be found from nature, where

biological systems have exploited chemical forces to create structure for cells needed for life. Whereas , top – down approach is uncommon/rare in nature.

3. Limitations to top – down approach are surfaces & edges are not perfect as they are wrinkly or containing cavities , wastage of material & restriction to get smaller size.

WHICH APPROACH IS BETTER?