INTRODUCTION TO NANOSCIENCE

AND NANOTECHNOLOGY

PHYS.472

Prof. Ali S. Hennache

Al-Imam Muhammad Ibn Saud Islamic University

Faculty of Sciences

Department of Physics

ASH/AIMISIU/CS/DP/RUH/05.06.2015/3.15PM/KSA

The course content has been structured to help the

student achieve the following objectives:

1. To gain an understanding of the principles of

nanotechnology; characterization of nano structured

materials; and tools and equipment for producing

and assembling at the nano scale.

2. To acquire experience in the use of equipment used in

nanotechnology .

3. To cultivate interest in the research and development

of nanotechnology for future advancement of the

career.

4. Discuss nanomaterials effects on medicine ,

environmental ,renewable energy, electronics etc....

Course Objectives /Outcomes

Reference Materials

1. Ratner , D. & Ratner, M. (2003). Nanotechnology: A

gentle introduction to the next big idea. New

Jersey: Pearson Education Inc, ISBN: 0131014005.

2. Charles P. Poole Jr. and Frank J. Owens (2003).

Introduction to Nanotechnology, Wiley-Interscience

, 1 st edition, ISBN-10: 0471079359

3. John F Mongillo (2007), Nanotechnology 101,

Greenwood Press, Westport, CT, ISBN: 0313338809.

4. Gabor L. Hornyak , H.F. Tibbals , Joydeep Dutta ,

and John J. Moore (2009). Introduction to

Nanoscience and Nanotechnology, CRC Press,

Boca Raton, ISBN 10: 1420047795.

Grading Policies

Course grade will be based on the following

components:

•Midterm Examinations (2): 2x 20 = 40%

•Home assignments – Quizzes = 15%

•Class participation = 5%

•Final Examination = 40%

ASH/AIMISIU/CS/DP/RUH/09.06.2015/KSA.6.44PM

The Exam Schedule for the

Summer 2015 Term

• Midterm Examination No.01 (20 marks)

MONDAY 22nd June 2015 @ 10.00AM

• Midterm Examination No.02 (20marks)

THURSDAY 02nd July 2015 @ 10.00AM

ASH/AIMISIU/CS/DP/RUH/09.06.2015/KSA.6.44PM

• QUIZ No.01 (5 marks)

TUESDAY 16th June 2015 @ 11.00AM

PHYS. 472

INTRODUCTION

TO

NANOTECHNOLOGY

Prof. Dr. Ali S. Hennache Department of Physics

College of Sciences

ASH/AIMISIU/CS/DP/RUH/05.06.2015/3.15PM/KSA

Content

Chapter 1- Introduction to nanoscience and nanotechnologies

Chapter 2- Principal synthesis techniques of nanosystems

Chapter 3- Quantification

Chapter 4- Porosity and texture of materials

Chapter 5- Nanomaterials and devices

Chapter 6- Deposition and etching of thin films

Chapter 7- Characterization techniques

Chapter 8- Devices based on thin films

X-Ray Diffraction (XRD )

Introduction Motivation:

• X-ray diffraction is used to obtain structural information about crystalline solids.

• Useful in biochemistry to solve the 3D structures of complex biomolecules.

• Bridge the gaps between physics, chemistry, and biology.

X-ray diffraction is important for:

• Solid-state physics

• Biophysics

• Medical physics

• Chemistry and Biochemistry

X-ray Diffractometer

History of X-Ray Diffraction

1895 X-rays discovered by Roentgen

1914 First diffraction pattern of a crystal made by Knipping and von Laue

1915 Theory to determine crystal structure from diffraction pattern developed by Bragg.

1953 DNA structure solved by Watson and Crick

Now Diffraction improved by computer technology; methods used to determine atomic structures and in medical applications

The first X-ray

How Diffraction Works

Wave Interacting with a Single Particle Incident beams scattered uniformly in all

directions

Wave Interacting with a Solid Scattered beams interfere constructively in

some directions, producing diffracted beams

Random arrangements cause beams to randomly interfere and no distinctive pattern is produced

Crystalline Material Regular pattern of crystalline atoms produces

regular diffraction pattern.

Diffraction pattern gives information on crystal structure

NaCl

nl=2dsin(Q)

• Similar principle to multiple slit experiments

• Constructive and destructive interference patterns depend on lattice spacing (d) and wavelength of radiation (l)

• By varying wavelength and observing diffraction patterns, information about lattice spacing is obtained

How Diffraction Works: Bragg’s Law

d Q Q

Q

X-rays of wavelength l

l

How Diffraction Works: Schematic

NaCl

A schematic of X-ray diffraction

Demonstration Array A versus Array B

•Dots in A are closer together than in B

•Diffraction pattern A has spots farther

apart than pattern B

Array E

•Hexagonal arrangement

Array F

•Pattern created from the word “NANO”

written repeatedly

•Any repeating arrangement produces a

characteristic diffraction pattern

Array G versus Array H

•G represents one line of the chains of

atoms of DNA (a single helix)

•H represents a double helix

•Distinct patterns for single and double

helices

A

C

E

G

B

D

F

H

Analyzing Diffraction Patterns

Data is taken from a full range of angles

For simple crystal structures, diffraction patterns are

easily recognizable

Phase Problem

Only intensities of diffracted beams are measured

Phase info is lost and must be inferred from data

For complicated structures, diffraction patterns at each

angle can be used to produce a 3-D electron density

map

Analyzing Diffraction Patterns

http://www.ecn.purdue.edu/WBG/Introduction/

d1=1.09 A

d2=1.54 A

nl=2dsin(Q)

The Laue Equations describe the intensity of a

diffracted peak from a single parallelopipeden

crystal

N1, N2, and N3 are the number of unit cells along the a1, a2, and a3 directions

When N is small, the diffraction peaks become broader

The peak area remains constant independent of N

3

2

33

2

2

2

22

2

1

2

11

22

/sin

/sin

/sin

/sin

/sin

/sin

ass

aNss

ass

aNss

ass

aNssFII

O

O

O

O

O

Oe

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

2.4 2.9 3.4

N=99

N=20

N=10

N=5

N=2

0

50

100

150

200

250

300

350

400

2.4 2.9 3.4

N=20

N=10

N=5

N=2

Which of these diffraction patterns

comes from a nanocrystalline material?

66 67 68 69 70 71 72 73 74

2 q (deg.)

Inte

nsi

ty (

a.u

.)

• These diffraction patterns were produced from the exact same sample

• Two different diffractometers, with different optical configurations, were used

• The apparent peak broadening is due solely to the instrumentation

Factors that Contribute to

the Observed Peak Profile Instrumental Peak Profile

Crystallite Size

Microstrain (µstrain) .An object under strain is typically deformed (extended or

compressed), and the strain is measured by the amount of this deformation relative

to the same object in an undeformed state. One microstrain is the strain producing

a deformation of one part per million (10-6).

Non-uniform Lattice Distortions

Faulting

Dislocations

Antiphase Domain Boundaries

Grain Surface Relaxation

Solid Solution Inhomogeneity

Temperature Factors

The peak profile is a convolution of the profiles from all of these

contributions

Contributions to Peak Profile

1. Peak broadening due to crystallite size

2. Peak broadening due to the instrumental

profile

3. Which instrument to use for nanophase

analysis

4. Peak broadening due to microstrain

• the different types of microstrain

Peak broadening due to solid solution

inhomogeneity and due to temperature

factors

Factors that affect K and

crystallite size analysis

how the peak width is defined

how crystallite size is defined

the shape of the crystal

the size distribution

46.7 46.8 46.9 47.0 47.1 47.2 47.3 47.4 47.5 47.6 47.7 47.8 47.9

2 q (deg.)

Inte

nsi

ty (

a.u.)

Methods used in Jade to Define

Peak Width Full Width at Half Maximum

(FWHM)

the width of the diffraction peak, in radians, at a height half-way between background and the peak maximum

Integral Breadth

the total area under the peak divided by the peak height

the width of a rectangle having the same area and the same height as the peak

requires very careful evaluation of the tails of the peak and the background

46.7 46.8 46.9 47.0 47.1 47.2 47.3 47.4 47.5 47.6 47.7 47.8 47.9

2 q (deg.)

Inte

nsi

ty (

a.u.)

FWHM

Applications of X-Ray

Diffraction

Find structure to determine function of proteins

Convenient three letter acronym: XRD

Distinguish between different crystal structures

with identical compositions

Study crystal deformation and stress properties

Study of rapid biological and chemical processes

…and much more!

Summary and Conclusions

X-ray diffraction is a technique for analyzing structures of biological molecules

X-ray beam hits a crystal, scattering the beam in a manner characterized by the atomic structure

Even complex structures can be analyzed by x-ray diffraction, such as DNA and proteins

This will provide useful in the future for combining knowledge from physics, chemistry, and biology

Goniometer

A goniometer is a device used in

physical therapy to measure the

range of motion around a joint in

the body. The word goniometer is

derived from the Greek terms

gonia and metron, which mean

angle and measure, respectively.

A goniometer is usually made of

plastic and is often transparent.

Occasionally goniometers are

made of metal. There are two

"arms" of the goniometer: the

stationary arm and the moveable

arm.

The XRD Technique

Takes a sample of the material and places a powdered sample which is then illuminated with x-rays of a fixed wave-length.

The intensity of the reflected radiation is recorded using a goniometer.

The data is analyzed for the reflection angle to calculate the inter-atomic spacing.

The intensity is measured to discriminate the various D spacing and the results are compared to known data to identify possible matches.

A goniometer is an instrument used to measure angles. Within the field of physical therapy, goniometry is used to measure the total amount of available motion at a specific joint. Goniometry can be usedto measure both active and passive range of motion.

Powdering Samples

The samples are powdered to give a random sampling

of ALL atomic planes (crystal faces)

Statistically accurate given samples are powdered

finely AND randomly oriented on sample holder

Intensities are a reflection of d-spacing abundance

Problems arise with minerals that may preferentially

orient on sample holder

Micas and clays have special preparation

techniques

X-Rays

Wavelengths

used for XRD

What is X-Ray Diffraction?

Crystalline substances

(e.g. minerals) consist of

parallel rows of atoms

separated by a ‘unique’

distance

Simple Example:

Halite (Na and Cl)

Na is the symbol for sodium

Cl is the symbol for chlorine

NaCl is sodium chloride

Crystalline substances (e.g. minerals) consist of parallel rows of atoms separated by a ‘unique’ distance

Diffraction occurs when radiation enters a crystalline substance and is scattered

Direction and intensity of diffraction depends on orientation of crystal lattice with radiation

Schematic X-Ray Diffractometer

X-Ray

Source

Powdered

sample

Detector

Sample XRD Pattern

background radiation

strong intensity = prominent crystal plane

weak intensity = subordinate crystal plane

Determine D-Spacing from XRD patterns

Bragg’s Law

nλ = 2dsinθ n = reflection order

(1,2,3,4,etc…)

λ = radiation wavelength

(1.54 angstroms)

d = spacing between

planes of atoms

(angstroms)

θ = angle of incidence

(degrees)

background radiation

strong intensity = prominent crystal plane

nλ = 2dsinθ

(1)(1.54) = 2dsin(15.5

degrees)

1.54 = 2d(0.267)

d = 2.88 angstroms

For electromagnetic radiation to be diffracted the spacing

in the grating should be of the same order as the wavelength

In crystals the typical interatomic spacing ~ 2-3 Å so the

suitable radiation is X-rays

Hence, X-rays can be used for the study of crystal structures

Beam of electrons Target X-rays

An accelerating (/decelerating) charge radiates electromagnetic radiation

Inte

nsi

ty

Wavelength ()

Mo Target impacted by electrons

accelerated by a 35 kV potential

0.2 0.6 1.0 1.4

White

radiation

Characteristic radiation →

due to energy transitions

in the atom

K

K

Target Metal Of K radiation (Å)

Mo 0.71

Cu 1.54

Co 1.79

Fe 1.94

Cr 2.29

Heat

Incident X-rays

SPECIMEN

Transmitted beam

Fluorescent X-rays Electrons

Compton recoil Photoelectrons Scattered X-rays

Coherent

From bound charges

Incoherent (Compton modified)

From loosely bound charges

X-rays can also be refracted (refractive index slightly less than 1) and reflected (at very small angles)

Refraction of X-rays is neglected for now.

Incoherent Scattering (Compton modified) From loosely bound charges

Here the particle picture of the electron & photon comes in handy

),( 11 Electron knocked aside

),( 22

11 hE

22 hE

)21(0243.012 q Cos

2q

No fixed phase relation between the incident and scattered waves

Incoherent does not contribute to diffraction

(Darkens the background of the diffraction patterns)

Vacuum

Energy

levels

KE

1LE

2LE

3LE

Nucleus

K

1L

2L

3L

Characteristic x-rays

(Fluorescent X-rays)

(10−16s later seems like scattering!)

Fluorescent X-rays Knocked out electron

from inner shell

A beam of X-rays directed at a crystal interacts with the electrons of

the atoms in the crystal

The electrons oscillate under the influence of the incoming X-Rays

and become secondary sources of EM radiation

The secondary radiation is in all directions

The waves emitted by the electrons have the same frequency as the

incoming X-rays coherent

The emission will undergo constructive or destructiv interference

with waves scattered from other atoms

Incoming X-rays

Secondary

emission

Sets Electron cloud into oscillation

Sets nucleus (with protons) into oscillation

Small effect neglected

Oscillating charge re-radiates In phase with the incoming x-rays

BRAGG’s EQUATION

d

q

q

q

q

The path difference between ray 1 and ray 2 = 2d Sinq

For constructive interference: n = 2d Sinq

Ray 1

Ray 2 q

Deviation = 2q

Laue’s Experiment in 1912

Single Crystal X-ray Diffraction

Tube

Collimator

Tube

Crystal

Film

Powder X-ray Diffraction

Tube

Powder

Film

Powder Diffraction Pattern

History:

W. H. Bragg and W. Lawrence

Bragg

W.H. Bragg (father) and

William Lawrence.Bragg

(son) developed a simple

relation for scattering

angles, now call Bragg’s

law.

q

sin2

nd

Another View of Bragg´s Law

n = 2d sinq

The Bragg Equation

where n is an integer

is the wavelength of the x-rays

d is the interplanar spacing in the specimen

q is the diffraction angle

The Bragg equation is the fundamental equation, valid

only for monochromatic X-rays, that is used to

calculate interplanar spacings used in XRD analysis.

q sin2dn

Diffractometer Components and

Geometry

Diffractometer

Diffractometer Geometry

Crystal Systems

Crystal systems Axes system

cubic a = b = c , = = = 90°

Tetragonal a = b c , = = = 90°

Hexagonal a = b c , = = 90°, =

120°

Rhomboedric a = b = c , = = 90°

Orthorhombic a b c , = = = 90°

Monoclinic a b c , = = 90° ,

90°

Triclinic a b c , °

Reflection Planes in a Cubic Lattice

The Elementary Cell

a

b

c

a = b = c = = = 90 o

Relationship between d-value and

the Lattice Constants

= 2 d s i n q Bragg´s law

The wavelength is known

Theta is the half value of the peak position

d will be calculated

1/d2= (h

2 + k

2)/a

2 + l

2/c

2

Equation for the determination of the

d-value of a tetragonal elementary cell

h,k and l are the Miller indices of the peaks

a and c are lattice parameter of the elementary cell

if a and c are known it is possible to calculate the peak position

if the peak position is known it is possible to calculate the lattice parameter

Interaction between X-ray and Matter

d

wavelength Pr

intensity Io

incoherent scattering

Co (Compton-Scattering)

coherent scattering

Pr(Bragg´s-scattering)

absorbtion

Beer´s law I = I0*e-µd

fluorescense

> Pr

photoelectrons

Powder Pattern and Structure

The d- spacings of lattice planes depend on the size of the elementary

cell and determine the position of the peaks.

The intensity of each peak is caused by the crystallographic structure, the

position of the atoms within the elementary cell and their thermal

vibration.

The line width and shape of the peaks may be derived from conditions of

measuring and properties - like particle size - of the sample material.

Principles of the Rietveld

method

Hugo M. Rietveld, 1967/1969

The Rietveld method allows the optimization of a

certain amount of model parameters (structure &

instrument), to get a best fit between a measured

and a calculated powder diagram.

The parameter will be varied with a non linear

least- squares algorithm, that the difference will

be minimized between the measured and the

calculated Pattern: S w y obs y calci i i

i

2

min

Basis formula of the Rietveld

method

SF : Scaling factor

Mk : Multiplicity of the reflections k

Pk : Value of a preferred orientation function for the reflections k

Fk2 : Structure factor of the reflections k

LP : Value of the Lorentz- Polarisations function for the reflections

k

Fk : Peak profile function for the reflections k on the position i

ybi : Value of the background at the position i

k : Index over all reflexes with intensity on the position i

y calc SF M P F LP yb obsik

k k k k k i k i 2 2 2 2