Nanomaterials - Synthesis and Characterization · PDF fileNanostructure Engineering Natural and Synthetic materials Nano-particles, wires, and tubes, etc Atoms/molecules BioMEMs, optical

Dr. Abdul kadir Masrom

General Manager

Nanotechnology Focal Point, SIRIM Bhd

Nanomaterials - Synthesis and

Characterization

Contents

Introduction

Definition

Standard terminology

Classification –

Nanomaterials

Properties and

characteristics of

nanoparticles

Nanomaterial synthesis

techniques

Nanomaterials

Characterization

Environmental, Safety and

Health Aspect

Nanostructure Engineering

Natural and

Synthetic materials

Nano-particles, wires,

and tubes, etc

Atoms/molecules

BioMEMs, optical displays,

sensors and biochips

Nanosensors,

nanoelectronics

separation, & healthcare

Molecular

Electronics

Chemical Synthesis

Self-assembly

STM & AFM Based Lithography

Electron, Ion-beam Lithography

Nanoimprint Lithography

Photolithography

Ink-jet Printing

Micro machining

Materials Applications Fabrication Platforms

Nano Materials and Technology is a multidisciplinary platform.

Introduction

Nanoparticles – not new –

dated back to fourth century

– damascus blade, roman

colored glass, Chinese Ink

They new the effect – but

they cannot explain what

caused the effect

WHY?but nanotechnology and

nanoscience are new

Why Nano so exciting?

What is actually so exciting about “nano”?

“Nano” means one billionth (10-9), so 1 nanometer

refers to 10-9 meter and is expressed as 1 nm.

1 nm is so small that things smaller than it can only

be molecules, clusters of atoms or particles in the quantum world.

ISO TC229-JWG1

Why is nanotechnology important?

US Interagency Working Group on Nano Science, Engineering and Technology

(IWGN) workshop on Nanotechnology Research Directions (Sept. ’99):

“nanotechnology will be a strategic branch of science and engineering for the 21st century,

one that will fundamentally restructure the technologies currently used for

manufacturing, medicine, defence, energy production, environmental management,

transportation, communication, computation and education.”

“It is estimated that Nanotechnology is presently at a level

of development similar to that of computer/information

technology in the 1950s” (Nanostructure Science and

Technology: A Worldwide Study, WTEC Panel report,

1999)

US NSF report on “SOCIETAL IMPLICATIONS OF NANOSCIENCE AND

NANOTECHNOLOGY” March 2001:

“the impact of nanotechnology in the 21st century is likely to be at least as significant for

health, wealth and security as the combined influences of antibiotics, integrated circuits

and polymers.”

Projected world-wide market for n-t enabled products

will be between $500 billion and $3 trillion by 2015

nanotechnologies• nanoscale

• nanoscale

attribute

nano-

measurement

nano-

processes

nano-

materials

nano-

production

devices/

applications

nano-

metrology

nano-

measuremt.

tools

nanoscale

objects

nano-

disper-

sions

nano-

structured

materials

complex

assemblies

nano-

medical.

devices

nano-

photonic.

devices

nano-

sensors

nano-

electronic

devices

Nanotechnology Field

Definitions

Definition

Nanoscale

Nano

technology

Nano

materials

Nano

science

Nano

particles

Nano-Object

Definition of nanoscience and

nanotechnology

Earliest definition given by the US National Nanotechnology Initiative (NNI):

nanoscience and –technology are “Research and technology development at the atomic, molecular and macromolecular levels in the length scale of approximately 1-100 nanometer range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size”.

Simply saying, nanoscience tells us how to understand the basic theories and principles of nanoscale structures, devices and systems (1-100 nm); and nanotechnology tells us what to do and how to use these nanoscale materials.

ISO Definition-STD definition

Nanoscale - size range from approximately 1 nm

to 100 nm

NOTE 1 Properties that are not extrapolations from a larger size will typically,

but not exclusively, be exhibited in this size range. For such properties the size

limits are considered approximate.

NOTE 2 The lower limit in this definition (approximately 1 nm) is introduced to

avoid single and small groups of atoms from being designated as nano-objects

or elements of nanostructures, which might be implied by the absence of a

lower limit.

Core Term - Definitions

• Nanomaterial: material having a geometric or structural feature in the nanoscale– NOTE Examples include nanocrystalline materials, nanoparticle powder, materials with nanoscale precipitates, nanoscale films,

nanostructured objects, nano-porous objects, and materials with nanoscale textures on the surface.

Supporting definitions defined in ISO/TS 27687:2008,

Nanotechnologies -- Terminology and definitions for nano-objects --

Nanoparticle, nanofibre and nanoplate

Nano-object: material with one, two or three external dimensions in the nanoscale. NOTE Generic term for all discrete nanoscale objects.

Nanostructured material: material with an external dimension larger than the nanoscale having an internal or surface structure at the nanoscale

Nanoparticle: nano-object with all three external

dimensions in the nanoscale.NOTE If the lengths of the longest to the shortest axes of the nano-object differ

significantly (typically by more than three times), the terms nanorod or nanoplate

are intended to be used instead of the term nanoparticle.

http://www.iso.org/iso/rss.xml?csnumber=44278&rss=detail

Working definitions reached by PG5

• Nanotechnology: the application of scientific knowledge to control and utilize matter at the nanoscale, where size-related properties and phenomena can emerge.

• Nanoscience: the systematic study and understanding of matter, properties and phenomena related to the nanoscale.

• nanoscale properties: properties related to the nanostructure of a given material or device.

Working definitions reached by PG5 (Cont.)

Nanoscale phenomena: phenomena occurring at the nanoscale where quantum confinement applies.

Nanosystem: a set of objects or components arranged or organized for a

specific function, with at least one dimension of the system at the nanoscale.

Question. Must a “nanosystem” function as a system at the “nanoscale” or is it a nanosystem

if just one component of the system functions at the nanoscale, yielding a purpose at a

larger-than-nano scale?

Nanodevice: an object or component designed for a purpose, with at least

one dimension at the nanoscale.

Nanotechnology Standard –

Terminology and Nomenclature

ISO -TC229

IEC - TC113

OECD –Working Party on Manufactured Nanomaterials

(WPMN)

CEN

ISO/TC 107

Metallic and

other inorganic

coatings

ISO/TC 38

Textiles

ISO/TC 59

Building

construction

ISO/TC 206

Fine ceramics

ISO/TC 122

PackagingISO/TC 119

Powder

metallurgy

ISO/TC 91

Surface active

agents

ISO/TC 84

Devices for

administration of

medical products and

intravascular

catheters

MATERIALS BIOMEDICAL

Map of current and potential liaisons for ISO/TC 229

ISO/TC 61

Plastics

ENERGY

ISO/TC 168

Prosthetics and

orthotics

ISO/TC 212

Clinical laboratory

testing and in vitro

diagnostic test

systems

ISO/TC 215

Health

Informatics

ISO/TC 225

Market

opinion and

social

research

ISO/TC 215

Environmental

management

ISO/TC 28

Petroleum and

petroleum

productsISO/TC 180

Solar energyISO/TC 203

Technical

energy systems

ISO/TC 184

Industrial

automation

systems and

integration

ISO/TC 172

Optics and

photonics

ISO/TC150

Implants for

surgery

ISO/TC 34

Food products

ISO/TC 217

Cosmetics

ISO/TC 48

Laboratory

equipment

ISO/TC 35

Paints and

varnishes

IEC/TC 113

Nanotechnology

Standardization

for electrical

and electronic

products and

systems

ISO

REMCO

ISO/TC 47

Chemistry

ISO TC 229

ISO/TC 212

Clinical laboratory


diagnostic test

systems

ISO/TC 202

Micro-beam

analysis

ISO/TC 201

Surface

chemical

analysis

ISO/TC 194

Biological

evaluation of

medical

devices

Asia Nano

Forum

CEN/TC 352

Nanotechnologies

EU JRC

Institute for Health

and Consumer

Protection

and

IRMMIUPAC

Terminology

committee

(ICTNS)

ISO/TC 135

Non-

destructive

testing

OECD

Working Party on

Manufactured

Nanometerials

METROLOGY AND

CHARACTERIZATION

RISK/HS&EEXTERNAL

LIAISONS

NANO-

PARTICLES

ISO/TC 146

Air quality

ISO/TC 209

Clean rooms and

associated

controlled

environments

ISO/TC 213

Dimensional and

geometrical product

specifications and

verification

ISO/TC 147

Water quality

ISO/TC 24

Sieves, sieving and

other sizing methods

VAMAS

ASTM E56

NanotechnologyOECD

WPN

ISO/TC 94

Personal safety –

Protective clothing

and equipment

IEC/TC 113

Nanotechnology

Standardization

for electrical

and electronic

products and

systems

ISO

REMCO

ISO

REMCO

ISO/TC 47

Chemistry

ISO/TC 47

Chemistry

ISO TC 229

ISO/TC 212

Clinical laboratory


diagnostic test

systems

ISO/TC 202

Micro-beam

analysis

ISO/TC 202

Micro-beam

analysis

ISO/TC 201

Surface

chemical

analysis

ISO/TC 201

Surface

chemical

analysis

ISO/TC 194

Biological

evaluation of

medical

devices

Asia Nano

Forum

CEN/TC 352

Nanotechnologies

EU JRC

Institute for Health

and Consumer

Protection

and

IRMMIUPAC

Terminology

committee

(ICTNS)

ISO/TC 135

Non-

destructive

testing

ISO/TC 135

Non-

destructive

testing

OECD

Working Party on

Manufactured

Nanometerials

METROLOGY AND

CHARACTERIZATION

RISK/HS&EEXTERNAL

LIAISONS

NANO-

PARTICLES

ISO/TC 146

Air quality

ISO/TC 209

Clean rooms and

associated

controlled

environments

ISO/TC 209

Clean rooms and

associated

controlled

environments

ISO/TC 213

Dimensional and

geometrical product

specifications and

verification

ISO/TC 213

Dimensional and

geometrical product

specifications and

verification

ISO/TC 147

Water quality

ISO/TC 24

Sieves, sieving and

other sizing methods

VAMAS

ASTM E56

NanotechnologyOECD

WPN

ISO/TC 94

Personal safety –

Protective clothing

and equipment

ISO/TC 94

Personal safety –

Protective clothing

and equipment

Needs for standardization1. To support commercialisation and market development

2. To provide a basis for procurement through technical requirements, and quality and environmental management

3. To support voluntary governance structures and appropriate legislation and regulation

Challenges: currently there are: No internationally agreed terminology/definitions for nanotechnology(ies).

No internationally agreed protocols for toxicity testing of nanoparticles.

No standardized protocols for evaluating environmental impact of nanoparticles.

Existing “methods of test” might not be suitable for nanoscale devices and nanoscale dimensions.

Measurement techniques and instruments need to be developed and/or standardized.

New calibration procedures and certified references materials are needed for validation of test instruments at the nanoscale.

Multifunction nanotechnology systems and devices will need new standards.

Partial solutions

Some existing standards are or might be applicable e.g. for chemical analysis and imaging (ISO TCs 201 and 202) and particle detection/sizing (ISO TC 24)

Project 2

Project 4

ISO/TC 229 JWG1: Strategic Roadmap

Nanosensors

Nanoelectronic

devices

Devices and

applications

Nanophotonic

devices

Terminology –

medical and

consumer

(IEC) Terminology –

nano-optics

(IEC) Vocabulary -

electrotechnical

Nanomedical

devices

Nanotechnologies

Nanomeasurement

Nano-

production

Nano-

processes

Base

Definitions

Nanoscale

attribute

Nanoscale

Framework and core

terms

Terminology -

nanofabrication

Terminology – nanoscale

measurement

Terminology –

nano-bio

interface

Nomenclature model

Nanometrology Nanomeasurement

tools

Nano films

Nanostructured

materials

Complex

assemblies

Nanoscale objects

Nanomaterials

Terminology -

nanoparticles

Terminology -

nanostructures

Terminology –carbon

nanostructures

Terminology -

nanomaterials

Nano

dispersions

Nomenclature- Model

OptionsProject 1

Nanomaterials classificationProject 3

Nanomaterials Classification

ISOTC229-Classification

OECD – engineered and accidental

Nanoparticles –WG1 ISO-TC229

NanocompositesA1

Nanoporous materialsA2

Nanocrystalline materialsA3

Core-shellsA4

NanoparticlesB1

NanocapsulesB2

DendrimersB3

Nanofilms and nanolayersC1

NanotubesD1

NanofibersD2

NanowiresD3

NanorodsD4

NanoclustersE1

Quantum dotsE2

Fullerenes(C60,C70,C80)E3

NanoonionsE4

DiamondoidsE5

dimension

Zero-D

1-D nanoparticle array – thin film, graphene

Dimension ----Internal/External Structure ------Type of

Nanomaterials


Nanomaterials


Nanomaterials

Properties and Characteristics

Thermal properties

Optical properties

Mechanical properties

Chemical properties

Copyright © 2005 SRI International

Unique Properties at the Nanoscale

The science behind nanotechnology

Are You a Nanobit Curious?

• What’s interesting about the nanoscale?

– Nanosized particles exhibit different properties than larger particles of the same substance

• As we study phenomena at this scale we…

– Learn more about the nature of matter

– Develop new theories

– Discover new questions and answers in many areas, including health care, energy, and technology

– Figure out how to make new products and technologies that can improve people’s lives

Properties of a Material

• A property describes how a material acts under certain conditions

• Types of properties

– Optical (e.g. color, transparency)

– Electrical (e.g. conductivity)

– Physical (e.g. hardness, melting point)

– Chemical (e.g. reactivity, reaction rates)

• Properties are usually measured by looking at large (~1023) aggregations of atoms or molecules

Sources: http://www.bc.pitt.edu/prism/prism-logo.gif

http://www.physics.umd.edu/lecdem/outreach/QOTW/pics/k3-06.gif

• The following factors are key for understanding nanoscale-related properties

– Dominance of electromagnetic forces

– Importance of quantum mechanical models

– Higher surface area to volume ratio

– Random (Brownian) motion

• It is important to understand these four factors when researching new materials and properties

What does this all means?

Size-Dependent Properties

How do properties change at the nanoscale?

Why do properties change?

At different scalesDifferent forces dominate Different models better explain phenomena

Optical Properties Example: Gold

• Bulk gold appears yellow in color

Sources: http://www.sharps-jewellers.co.uk/rings/images/bien-hccncsq5.jpg

http://www.foresight.org/Conferences/MNT7/Abstracts/Levi/

12 nanometer gold particles look red

If you cut a block of gold into smaller & smaller pieces, it would still look like gold

• Nanosized gold appears red in color

– The particles are so small that electrons are not free to move about as in bulk gold

– Because this movement is restricted, the particles react differently with light

“Bulk” gold looks yellow

at the nanoscale -properties change!

Optical properties The optical properties of

nanomaterials differ

remarkably from bulk

materials. This difference can

be mainly attributed to the

quantum confinement

effects, unique surface

phenomena, and efficient

energy and charge transfer

over nanoscale distances

within nanomaterials.

The origin of the color difference in the cup is attributed to the

optical response of colloidal nanoparticles of gold dispersed in the

glass

result from localized

surface plasmons

Lycurgus Cup from the 4th century AD

“Traditional” ZnO sunscreen is white

Zinc oxide nanoparticles

Nanoscale ZnO sunscreen is clear

Sources: http://www.apt powders.com/images/zno/im_zinc_oxide_particles.jpg

http://www.abc.net.au/science/news/stories/s1165709.htm

http://www.4girls.gov/body/sunscreen.jpg

Optical Properties Example:Zinc Oxide (ZnO)

• Large ZnO particles

– Block UV light

– Scatter visible light

– Appear white

• Nanosized ZnO particles

– Block UV light

– So small compared to the wavelength of visible light that they don’t scatter it

– Appear clear

Optical Properties - TiO2 and ZnO Scattering of visible light (whitening effect) is

influenced by particle size and the difference

between the refractive index of the pigment

and the surrounding media.

Wavelength

Particle size

• Maximum scattering occurs when

size equals 1/2 the wavelength and

particles are uniformly dispersed

(Mie theory).

TiO2 Dispersions

195 60 35 15 10

nm

195 60 35 15 10

nm

195 60 35 15 10

nm

195 60 35 15 10

nm

10nm TiO2 (110 nm dispersion particle size) makes transparent

dispersions for all skin types.www.koboproducts.com

Source: http://www.weizmann.ac.il/chemphys/kral/nano2.jpg

Electrical Properties Example: Conductivity of Nanotubes

• Nanotubes are long, thin cylinders of carbon

– They are 100 times stronger than steel, very flexible, and have unique electrical properties

• Their electrical properties change with diameter, “twist”, and number of walls

– They can be either conducting or semi-conducting in their electrical behavior

Electric current varies by tube

structure

Multi-walled

Electronic properties As the particle size decreases

below the Bohr radius of the

semiconductor material, the

electron becomes more confined in the

particle. This leads to an increase

in the band gap energy and the

valence and conduction bands

break into quantized energy

levels. The band gap emission shown is observed to shift through

the entire visible region, from red emission for the largest

particles, to blue emission for the smallest clusters.

• For example the effect of

changing the particle size of CdSe

nanoparticles.

Sources: http://puffernet.tripod.com/thermometer.jpg and

image adapted from http://serc.carleton.edu/usingdata/nasaimages/index4.html

Physical Properties Change:Melting Point of a Substance

• Melting Point (Microscopic Definition)

– Temperature at which the atoms, ions, or molecules in a substance have enough energy to overcome the intermolecular forces that hold the them in a “fixed” position in a solid

In contact with 3 atoms

In contact with 7 atoms

– Surface atoms require less energy to move because they are in contact with fewer atoms of the substance

Physical Properties Example:Melting Point of a Substance II

At the macroscale At the nanoscale

The majority of the atoms are…

…almost all on the inside of the object

…split between the inside and the surface of the object

Changing an object’s size…

…has a very small effect on the percentage of atoms on the surface

…has a big effect on the percentage of atoms on the surface

The melting point…

…doesn’t depend on size

… is lower for smaller particles

Scale Changes Everything II

• Four important ways in which nanoscalematerials may differ from macroscale materials

– Gravitational forces become negligible and electromagnetic forces dominate

– Quantum mechanics is the model used to describe motion and energy instead of the classical mechanics model

– Greater surface area to volume ratios

– Random molecular motion becomes more important

Dominance of Electromagnetic Forces

• Because the mass of nanoscale objects is so small, gravity becomes negligible

Sources: http://www.physics.hku.hk/~nature/CD/regular_e/lectures/images/chap04/newtonlaw.jpg

http://www.antonine-education.co.uk/Physics_AS/Module_1/Topic_5/em_force.jpg

• Gravitational force is a function of mass and distance and is weak between (low-mass) nanosized particles

• Electromagnetic force is a function of chargeand distance is not affected by mass, so it can be very strong even when we have nanosizedparticles

• The electromagnetic force between two protons is 1036 times stronger than the gravitational force!

Macrogold

Sources: http://www.phys.ufl.edu/~tschoy/photos/CherryBlossom/CherryBlossom.html

http://www.nbi.dk/~pmhansen/gold_trap.ht; http://www.sharps-jewellers.co.uk/rings/images/bien-hccncsq5.jpg;

Quantum Effects

• Classical mechanical models that we use to understand matter at the macroscale break down for…

– The very small (nanoscale)

– The very fast (near the speed of light)

• Quantum mechanics better describes phenomena that classical physics cannot, like…

– The colors of nanogold

– The probability (instead of certainty) of where an electron will be found

Nanogold

Surface Area to Volume Ratio Increases

• As surface area to volume ratio increases

– A greater amount of a substance comes in contact with surrounding material

Source: http://www.uwgb.edu/dutchs/GRAPHIC0/GEOMORPH/SurfaceVol0.gif

– This results in better catalysts, since a greater proportion ofthe material is exposed for potential reaction

Figure - Calculated surface to bulk ratios for solid metal particles versus size.39 The % of surface atoms increases while the % of bulk atoms decrease when going to nanometer scales.

Source: http://www.ap.stmarys.ca/demos/content/thermodynamics/brownian_motion/rand_path.gif

Random Molecular Motion is Significant

• Tiny particles (like dust) move about randomly

– At the macroscale, we barely see movement, or why it moves

– At the nanoscale, the particle is moving wildly, batted about by smaller particles

• Analogy

– Imagine a huge (10 meter) balloon being batted about by the crowd in a stadium. From an airplane, you barely see movement or people hitting it; close up you see the balloon moving wildly.

Surface Plasmon Resonance

- Oscillation of free electrons

on metal surface at polarized

electromagnetic radiation

- E-band was changed by

reflective index of near region

• Surface analysis sensor

- Detection of index change in

refractive of medium

- Non-labeling detection tool

- Protein detection 10-9 ~ 10-10

- Small molecules X (<1 kDa)

Surface plasmon resonance Application of SPR

Sensitivity enhancement of SPR signal

나노 구조체 제조Au evaporation Silica particle remove

Well-orderd 2D colloidal film A thin layer was deposited Periodic nanostructure

prism

Image processing

Gold layer

Novel SPR sensor chip

Fabrication of nanostructure

* Fabrication of nanostructure

SPR sensor chip

Magnetic properties Study of magnetic

properties of nanoparticlesin the size range of 1-100 nm is an important area

applications such as magnetic resonance imaging (MRI) for medical diagnosis, high-density magnetic recording, magneto-optical switches, therapeutic and controlled drug delivery.

Synthesis Technique

Top-Down

Bottom-up

Method for Synthesis of Nanomaterials

How to get at nano scale?

Top–down or bottom–up?

What is top-down approach?

What is bottom-up approach?

UltimateGoal:

Dial in the properties that you want by

designing and building at the scale of nature

(i.e., the nanoscale)

Reactant 1 + Reactant 2 Product + …T, p, t

Sonochemistry

Microwave

synthesis

Hydrothermal

methods

Microencapsulation

Sol-gel

methods

Wet chemical

co-precipitation

How to get at nano scale• There are two general approaches to the synthesis of

nanomaterials and the fabrication of nanostructures

Bottom-up approachThese approaches include the miniaturization of materials components (up to atomic level) with further self-assembly process leading to the formation of nanostructures. During self-assembly the physical forces operating at nanoscale are used to combine basic units into larger stable structures.

Typical examples are quantum dot formation during epitaxial growth and formation of nanoparticles from colloidal dispersion.

Top-down approachThese approaches use larger (macroscopic) initial structures,which can be externally-controlled in the processing of nanostructures.

Typical examples are etching through the mask, ball milling, and application of severe plastic deformation.

Top-down methods

• begin with a pattern

generated on a larger

scale, then reduced to

nanoscale.

• By nature, aren’t cheap

and quick to manufacture

– Slow and not suitable for

large scale production.

Bottom-up methods

• start with atoms or

molecules and build up

to nanostructures

• Fabrication is much less

expensive

Top-down versus Bottom-up

Bottom-up Process - What to control

• Colloidally stable nanoparticles

• Reproducible

• Adaptable surface properties

• Easy + cheap

•(Biocompatible or biodegradable systems)

• Gaseous Phase Method

• Principal: Gas –phase precursors interact with a liquid–or solid-phase material

• Gas state condensation• Chemical vapor deposition• Molecular beam epitaxy• Atomic layer deposition• Combustion• Thermolysis• Metal oxide vapor phase

epitaxy• Ion implantation

• Liquid Phase Fabrication Method

• Molecular self-assembly• Supramolecular chemistry• Sol-gel processes• Single-crystal growth• Electrodeposition /

electroplating• Anodizing• Molten salt solution

electrolysis• Liquid template synthesis• Super-critical fluid expansion

Liquid Phase Synthesis

• Precipitating nanoparticles from a solution of chemical compounds can be classified into five major categories:

• (1)colloidal methods;

• (2)sol –gel processing;

• (3) water –oil microemulsionsmethod;

• (4) hydrothermal synthesis; and

• (5) polyolmethod.

Sol-Gel ProcessThe sol is a name of a colloidal solution made of

solid particles few hundred nm in diameter,

suspended in a liquid phase.

The gel can be considered as a

solid macromolecule immersed

in a solvent.

Sol-gel process consists in the chemical

transformation of a liquid (the sol) into a gel state

and with subsequent post-treatment and transition

into solid oxide material.

The main benefits of sol–gel processing are the high

purity and uniform nanostructure achievable at low

temperatures.

• Start with precursor• Form Solution (e.g.,

hydrolysis)• Form Gel (e.g.,

dehydration)• Then form final

product• Aerogel(rapid drying)• Thin-films (spin/dip) In solgel chemistry, molecular precursors are converted to

nanometer-sized particles, to form a colloidal suspension, or sol.

Adding epoxide to the sol produces a gel network. The gel can be

processed by various drying methods (shown by the arrows) to

develop materials with distinct properties.

Sol-Gel Process

Advantage & Disadvantage – Sol-Gel Method

• Sonochemistry is the application of

ultrasound to chemical reactions and

processes. The mechanism causing

sonochemical effects in liquids is the

phenomenon of acoustic cavitation.

• [Ultrasound] causes cavitation which causes local extremes of temperature and pressure in the liquid where the reaction happens.*

• It breaks up solids and removes passivating layers of inert material to give a larger surface area for the reaction to occur over.*

• Biological cells including bacteria can be disintegrated.

• “Experimental results have shown that these bubbles have temperatures around 5000 K, pressures of roughly 1000 atm… These cavitations can create extreme physical and chemical conditions in otherwise cold liquids.”*

Sonochemical Reaction and Synthesis

Schematic representation of the reactive regions of a collapsing

cavitation bubble.

https://secure.wikimedia.org/wikipedia/en/wiki/Cavitation

https://secure.wikimedia.org/wikipedia/en/wiki/Passivation

https://secure.wikimedia.org/wikipedia/en/wiki/Inert

https://secure.wikimedia.org/wikipedia/en/wiki/Surface_area

Sonochemical Nano-Synthesis• Sonochemistry: molecules undergo a chemical reaction due to

application of powerful ultrasound (20 kHz – 10 MHz)– Acoustic cavitation can break chemical bonds

– “Hot Spot” theory: As bubble implodes, very high temperatures ( 5,000 –25,000 K) are realized for a few nanoseconds; this is followed by very rapid cooling (1011 K/s)

– High cooling rate hinders product crystallization, hence amorphous nanoparticles are formed

Superior process for:• Preparation of

amorphous products • Insertion of nano-

materials into mesoporous materials

• Deposition of nanoparticles on ceramic and polymeric surfaces

Sonochemical Nano-Synthesis: Examples

• Gold, Co, Fe, Pg, Ni, Au/Pd, Fe/Co

• Nanophased oxides (titania, silica, ZnO, ZrO2, MnOx

– More uniform dispersion, higher surface area, better thermal stability, phase purity of nanocrystalline titania reported

• MgO coating on LiMn2O4

• Magnetic Fe2O3 particles embedded in MgB2 bulk

• Nanotubes of C, hydrocarbon, TiO2, MeTe2

• Nanorods of Bi2S3, Sb2S3, Eu2O3, WS2, WO2, CdS, ZnS, PbS, Fe3O4

RMK9 Science Fund: Development of Novel Production of

nanometal and nanometal oxide by high intensity ultrasound

approach.

nanometals: Au, Ag, Co

Nano metaloxide: TiO2, Fe2O3

Experimental set-up for

sonochemistry experiments

Au(left) & Co(right) nanopraticles produced in SIRIM by

sonochemical method

Nanorods (or Nanowires) Synthesis

Techniques can be grouped into two categories:

• Spontaneous growth:

- Evaporation condensation

- Dissolution condensation

- Vapor-Liquid-Solid growth (VLS)

- Oxide-Assisted Growth (OAG)

• Template based synthesis:

- Electrochemical deposition

- Surface Step-Edge Templates

Template Based Synthesis

General Aspects:

• Simple, versatile, easy to control technique

• Fabricates various materials; polymers, metals, semiconductors,

and oxides on a single structure.

• Porous membrane with nano-size channels (pores) are

used as templates

• Pore size ranging from 10 nm to 500 nm can be achieved.

Template Based synthesis

Electrochemical Deposition

• This is a self-propagating process.

• This method is an electrolysis in a pre-formed space

resulting in the deposition of solid materials on an electrode.

• Only applicable to electrically conductive materials: metals,

alloys, semiconductors, and electrical conductive polymers.

• The diameter of the nanowires is determined by the geometrical constraint of the pores.

• Fabrication of suitable templates is a critical step.

• By careful removal of the template, free standing nanowires can be fabricated.



growth speciesElectric field

direction

porous

membrane



◆ Electrolysis (or electroplating)

• Upon external field is applied, the process can be reversed or

electrical energy converts to chemical potential - electrolysis

• Cathode - to be plated (NW fabrication), reduction (working electrode)

• Anode – plating metal (Ag), oxidation, Noble metals are often used

as an inert electrode (counter electrode)

Electroplating:

requires a redox

process in an

electrochemical cell



S-H Park, J-H Lim, S-W Chung, Chad A. Mirkin, Science,2004 303 348-351

• nanorods from 200 nm AAO template



◆ Elements can be Electrodeposited

H He

Li Be B C N O F Ne

NA Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Se Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac

• Elements plateable from aqueous solutions (red background).

• Elements with yellow background are only plateable

in combination with one of the others (alloy plating).

Pd- PdCl2 (1.5 g/L) + Disodium ethylenediaminetetraacetate (Na2-EDTA · 2H2O, 40.1 g/L)+ NH3·H2O (28%, 195mL/L) + N2H4 (1 M, 5 mL/L)

Ag - Solution A: AgNO3 (2 g/L) + Na2-EDTA· 2H2O (60 g/L) + Isopropyl alcohol (88 mL/L)

+ Acetic acid (12 mL/L) + NH4OH (400 mL/L)- Solution B: Hydrazine (3 mL/L) + Mercerine (2 mL/L) + Ethanol (400 mL/L)

Mixture solutions of A and B at 1:1 (v/v)

Au - KAu(CN)2 (5 g/L) + KCN (8 g/L) + NaOH (20 g/L) + Glycine (10 g/L) + NaBH4 (25 g/L)

Cu - Solution A: CuSO4 (30 g/L) + Sodium potassium tartrate (Rochelle salt, 140 g/L)

+ NaOH (40 g/L)- Solution B: Aqueous formaldehyde solution (37.2 wt %)

mixture solutions of A and B at 10:1 (v/v)

Ni - NiSO4·6H2O (15 g/L) + H3C6H5O7·6H2O (18 g/L) + NaH2PO2·H2O (30 g/L) + NaCH3COO·3H2O (28 g/L) + Latic acid (85%, 20 mL/L) + Thiourea (2 mg/L)



◆ Typical metal electroplating solution conditions


Template Construction

• Common templates:

- Porous alumina, nanochannel glass, ion track-etched

polymers, mica films, di-block copolymers

• Porous alumina is fabricated by electrochemical

etching of aluminum using under various acids

• Pore diameter controlled by potential and acid

concentration

- < 10 nm ~ 500 nm

- 109 ~ 1011 pores/cm2

Sachiko Ono, Makiko Saito, Hidetaka Asoh Electrochimica Acta 2005 51 827–833

Honeycomb model structure

of anodic porous alumina.

Voltages and corresponding

cell diameters

Circulator

electrode

Water

jacket

Stirrer

Power

Supply(1)

Power

Supply(2)

Anodizing

Removal of porous alumina layer

Electro polishing

Experimental set up for Fabrication


Template synthesis

Electrochemical Deposition Materials

Metal

Au (H2O 20 ml + 50 mM KAg(CN)2+ 0.25 M Na2CO3(pH 13)),

Ag (H2O 20 ml +50 mM KAu(CN)2 + 0.25 M Na2CO3(pH 13)),

Ni (H2O 20 ml + 1 mM NiSO4 + 0.1 M Na2SO4),

Cu (H2O 20 ml + 2 mM CuSO4 + 0.1 M Na2SO4)

Semi-

conductorCdSe (H2O 20 ml + 0.3M CdSO4 + 0.7mM SeO2 + 0.25M H2SO4)

PolymerPolypyrrole (Acetonitrile 20 ml + 10 mM pyrrole + 0.1 M TEABF4),

Polyaniline (H2O 20 ml + 0.5 M aniline + 0.2M HCl)

* TEABF4: tetraethylammonium tetrafluoroborate

Au

(Orotemp 24 RTU, No. 210927)

Ag

(1025 RTU, No. X7522000),

Ni

(Nickel sulfamate RTU, No. 030179)

Homepage : http://www.technic.com

Properties and Application of NR (or NW)

Single-layer nanorod Multi-layer nanorod

MetalSemi-

conductor

Conducting

polymerMetal–Metal–Metal

Metal– Semi -Metal

conductor

Metal – Conducting – Metal

Polymer

Au, Ag, Ni CdSe Polypyrrole Au-Ag(Ni)-Au Au-Cd/Se-Au Au-polypyrrole-Au

* Cd/Se nanorod : 0.1㎛ / 800 cycle (cycle voltametry method)

Au Ppy

Ag Ni

CdSe

*Measurement : Energy dispersive X-ray spectrometry


Template : Homemade AAO

NRs diameter : 25 ± 5 nm

20 nm

35 nm

30 nm

30 nm

30 nm

35 nm

35 nm

35 nm

40 nm

Au rod in AAO (photo)

◆ Single layer nanorod (quantum confinement)


1 mm

Au

AuAg

PPy

500 nm

Au

Ni

1 mm

Au

PPy

1 m m

Au

PANI

Multilayer nanorods


CdSe particle embedded polypyrrole nanorod

AAO

Au

AuCdSe

+PPy

NaOH

< TEM image >

Au nanorod

CdSe particle

PPY nanorod

< Fluorescent microscope image>

20 nm

< SEM image >

CdSe particle size: 3.7 ~ 4.3 nm


Polymer-Metal Core-Shell structure

AAO

Au

Au/PPy Au NaOH

PPy-Au

core-shell

structures

100 nm


Au particle embedded polypyrrole nanorod

AAO

Au

AuAu colloid

+PPy

NaOH

Au

PPY

Au colloid size :

20 nm


CdSe particle embedded polypyrrole nanorod

AAO

Au

AuCdSe

+PPy

NaOH

< TEM image >

Au nanorod

CdSe particle

PPY nanorod

< Fluorescent microscope image>

20 nm

< SEM image >

CdSe particle size: 3.7 ~ 4.3 nm


Nanorod (or Nanowire) Synthesis

Spontaneous Growth

General Ideas:

• Anisotropic growth is required.

• Crystal growth proceeds along one direction, where as

there is no growth along other direction.

• Uniformly sized nanowires (i.e. the same diameter along

the longitudinal direction of a given nanowire)

Spontaneous Growth

Evaporation Condensation

• Referred to as Vapor-Solid (VS) technique

• NRs (or NR) grown by this method are commonly single crystalswith fewer imperfections.

• The formation of NR (or NR) is due to the anisotropic growth.

• The different facets in a crystal have different growth rates.

• No control on the direction of growth of NR (or NR) in this method.

Spontaneous Growth

Evaporation condensation

Nanostructures of zinc oxide

(a) Model of a polar nanobelt. Polar-surface-induced formation of (b) nanorings,

(c) nanospirals, and (d) nanohelixes of ZnO and their formation processes.

Design and Synthesis of Monodisperse Nanoparticles

• Example 1.

• Park et al. has shown that by using a metal chloride precursor with sodium oleate, an intermediate metal-oleate complex is formed. When this complex is heated, using thermal decomposition techniques, the resulting products are monodisperse nanoparticles

• Example 2

• Sun et al. highlighted the synthesis of monodisperse FePt nanoparticles by also using thermal decomposition and utilizing both oleic acid and oleyl amine as surfactants. In their process, they also found that the surfactants prevented the particles from oxidation.

(74) Park, J.; An, K. J.; Hwang, Y. S.; Park, J. G.; Noh, H. J.; Kim, J. Y.; Park, J. H.;

Hwang, N. M.; Hyeon, T. Nat. Mater. 2004, 3, 891. Sun, S.; Murray, C. B.; Weller, D.; Folks, L.; Moser, A. Science 2000, 287, 1989.

• Different polyols are chosen

depending on the reduction potential

of the metals; easily reducible metals

which do not require high heat can be

reduced in butylene glycol, while less

easily reducible metals require higher

temperatures and tetraethylene glycol

is required.

• It has been proposed that the

reduction of metals in a liquid polyol

medium occurs by dissolution of the

metal salt precursor, reduction by the

polyol of the dissolved species, and

nucleation and growth of the metal

particles from the solution.

Various polyols used for the reduction of metal salt precursors. Varying

the hydroxyl sites has an effect on the overall reduction potential of the

polyol along with a boiling point change.

Polyol Process

Example

Example: Facile synthesis of Fe nanoparticles by the aqueous method

• iron(II) sulfate or iron(II) chloride are dissolved in distilled water, where it dissociates into Fe2+ and SO42- or Cl-

ions.

• Synthesis is simple – but protecting the particles from eventual oxidation has been a challenge.

• One way to protect the particles from significant oxidation - by performing the reaction carefully in de-oxygenated water.

• However, the oxidation and agglomeration has been still a significant problem associated with the borohydride

The Fe2+ ions then form an aqua complex with six

water molecules. The Fe2+ is reduced to Fe0 by the

use of a reducing agent, sodium borohydride

The resulting Fe atoms undergo nucleation and

growth and eventually grows into clusters of various

morphologies

• Use of surfactants may

help by stabilizing the

particles from

oxidation and growth.

• synthesis of elemental

Fe nanoparticles by

using sodium citrate as

a surfactant. Ekeirt et al.84

• Optimum Citrate to Fe ratio ([Cit]/[Fe2+]) 10/1

• Produced 100 nm clusters of 5 nm alpha-Fe nanoparticles.

• 100 nm clusters were protected from oxidation by a citrate shell formed around the particle, even in highly oxygen-rich environments.

Ekeirt, T. F., University of Delaware, 2010.

Design of Core/Shell nanoparticles

• What is core/shell

nanoparticles?

• What is the purpose of

designing this

structure?

• Examples of core/shell nanoparticles:

• Fe/Fe3O4,

• gold and silver-coated iron oxide (Fe2O3 or partially oxidized Fe3O4), and

• Fe3O4/SiO2

• Magnetic core Ag/Ni and Au/Ni for the investigation of the magnetic tunability by manipulating the size of core and shell

Preparation of Fe/Ag and Ag/Fe core/shell

nanoparticles

High resolution TEM image of (a) as-synthesized Fe nanoparticles,(b) Fe/Ag nanoparticles

showing a clear distinction between the core (Ag) and shell (FeB/Fe2B) (c) Ag/Fe

nanoparticles, and (d) Fe nanoparticles with islanding of Ag. Kyler James Carroll B.S., Aquinas College, 2007

TEM images of (A) Fe/SiO2 nanoparticles and (B)

Fe/SiO2/Au nanoparticles

Shows typical TEM images of the as-prepared 80 nm Core/shell Fe/SiO2 NPs with an iron

core of 75 nm and a SiO2 shell of 5 nm and the Fe/SiO2/Au NPs with Au islands of 4-5

nm. Kyler James Carroll B.S., Aquinas College, 2007

Different morphology

The synthesis of the polyol reaction can yield various

elemental Cu morphologies by simply varying the

reaction medium.

Kyler James Carroll B.S., Aquinas College, 2007

SIRIM Research Interest – Next 3 Years

•Mesoporous Materials of TiO2,SiO2 and Carbon –

synthesis and application as Catalysis, Photo catalyst for

environmental remeadiation

•Graphene research – synthesis and applications as

electrode for solar cell, energy storage and conducting

polymer

•Self assembly process

•Nanoparticles functionalisation process,

characterisation and applications

Characterization Techniques

Imaging & Microscopy

Electrical

Chemical

Mechanical

Surface

ISOTC 229-WG3 activities

Nanomaterials - Characteristics

Advanced Character set

Electrical, Magnetic, Mechanical , Optical properties

Carbon Nano-Materials

Engineered

nanoparticles

Coatings/

Nanostructured materials

Basic Metrology

Basic Character set

Purity Geometrical property

Morphology Dispersability Tube type

2005 2010 2015


Elemental structure, Chemical functionality,

Electrical, Magnetic, Mechanical , Optical properties

Basic Character set

Purity Composition, Geometrical property, Sampling method.


Electrical, Magnetic, Mechanical , Optical

properties

Basic Character set

Geometrical property, Composition, Density

Length, Depth, Force, Traceability, Definition of Measurand, Uncertainty

Interoperability

Common polyethylene terephthalate (PET) polymer C

1s spectra with peak fitting.

AFM measurement diagram

Introduction of AFM (atomic force microscope) Ultra high-resolution type of scanning probe microscope

Invented by Binnig, Quate and Gerber in 1986

One of the foremost tools for imaging, measuring and manipulating

matter at the nano-scale Commercial AFM Tip

- low cost ( >100 $/ea)

- low durability

- tip diameter : ~ 10 nm

Commercial CNT Tip

- high cost ( >1000 $/ea)

- high durability

- tip diameter : ~ 3 nm

- high resolution image

http://upload.wikimedia.org/wikipedia/en/1/1a/Atomic_force_microscope_block_diagram.png

Dielectrophoresis process

CVD nanotube tip growth method SEM & TEM image of SWNT bundles grown

from a Si cantilever tip

CNT-tip-manipulation under FE-SEM

Method 1Method 1

Method 2Method 2 Method 3Method 3

CNT-tip fabrication methods

Disadvantage ; very expensive techniques, low productivity, too difficult to control alignment of CNTs

Measurement of porous membrane

Conventional AFM tip

Spike

CNT-tip

Spike

Spike diameter Tip radius

Conventional AFM tip 25~30nm About 10 nm

CNT-tip 7~10 nm 1.5~2 nm

200 K

×

5 nm

20 nm200 K

×

5 nm

20 nm

Porous AAO

SEM image

High resolution images

biomaterials

??

assembly

3~5 nm

CNT + AFM probe = CNT AFM probe

20 nm

DNA standard sample

30 nmDNA

hIgG antibody sample

Measurement of bio-materials

TMV (tobacco mosaic virus) Tobacco Mosaic Virus

2130 identical coat protein molecules

Right-handed helix along RNA

-18 nm outer diameter

- 4 nm inner cavity 100 nm

TEM image

60 nm 60 nm

Height : 18 nm

High resolution AFM images of TMV virus using CNT tip

SWNT bundle

2~3 nm

TMV coat protein onto RNA scaffold

Tobacco leaf

Measurement- Model : DI-AFM

- Mode : Tapping mode

- Resonance frequency : 312 Hz

3D AFM images of TMV virus

Measurement of virus

http://www.mardre.com/homepage/mic/tem/samples/bio/virus/tmv1.jpg

Measurement of DNA-CNT

DNA-encapsulated SWNT on the H-passivated Si(111) surfaces

Line width : 4.1 0.2 nm+

4.03 nm

Hersam Research Group

w/ Mark C. Hersam co-work

Field Induced Oxidation Nano-patterning

Goal : High resolution FIO nano-patterning using SWNT probe

Si + 4H + 2OH SiO + 2H2

+

+

-

SWNT probe

SiO2

Using tapping mode


w/ Mark C. Hersam co-work

Mode : tapping mode

Set point; -0.065 um

Drive : 30.14 %

Humidity : 30% ~ 50%

10V9V8V7V6V5V

1 sec

2 sec

3 sec 10V9V8V7V6V5V

Smallest width : 21 nm

Smallest height : 0.86 nm

Smallest width : 23 nm

Smallest height : 1.1 nm

AFM images of an oxide pattern written on

a H-passivated Si surface


ESH

Main issues when dealing with Nanotechnology – especially

dealing with nanomaterials

Issues on surface reactivity and toxicity

Effect to environment, safety and health of workers as well as

users.

Refer to OECD –Working Party on Manufatured

Nanomaterials

Standard Methods for

Toxicological

Screening

of Nanomaterials


Determining Relative

Toxicity/Hazard Potential of

Nanomaterials


Controlling Occupational

Exposures to Nanomaterials

Future Screening

Test TBD

In vivo Tox Test TBD

In vitro Tox Test TBD

Metrology TBD

Terminology TBD

Workplace Monitoring

Metrology TBD

Terminology TBD

Current

Practices TR

Future Occupational

Standards TBD

2008 20102009

Seq

ue

nc

e

Nanoparticle

Toxicity Testing

Physico-Chemical

characterization

Endotoxin Test

Metrology TBD

Terminology TBD

Nanoparticle

Inhalation Testing

Future NWIP TBD

ISO/TC 229 WG3 : Strategic Roadmap

2011

Thank You

Documents

Nanomaterials - Synthesis and Characterization · PDF fileNanostructure Engineering Natural and Synthetic materials Nano-particles, wires, and tubes, etc Atoms/molecules BioMEMs, optical