Nafila Khuzaimatun Nafi’ah

195160101111015

RESUME
VP Nanomaterial (Dry Partical) XRD

X-ray diffraction

Content

Brief history and introduction

- Applications of x-ray (in general)

- X-ray diffraction and basic princip

- Instrumentation/components

- Bragg's and Scherrer's equation

- Basic of crystallography/Miller indices

- XRD pattern and FWHM

- Phase identification

- Sample preparation

- Application of PXRD

- Advantages/disadvantages

- PXRD Characterisation for Nanomaterials: nanoparticles, carbon

nanostructures, 2D nanolavered structure, 30 AC, the collapse of 20

layered structure

- Application of PXRD in dentistry

- Summary

History of X-rays

Anna Bertha Rontgen

Wilhelm Conrad Rontgen

1901: The First Nobel Prize in Physics

In 1895 Rontgen discovers X-rays

Nafila Khuzaimatun Nafi’ah
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Max von Laue

1914: The Nobel prize for physics

The discovery of the diffraction of X-rays by

crystals "Diffraction pattern"

W. H. Bragg and his son W. L. Bragg and the

diffraction of x-rays by crystals.

1915: The Nobel prize for physics

The analysis of crystal structure by means of X-rays

POWDER X-RAY DIFFRACTION (PXRD)

Primarily used for phase identification of a crystalline material

phase-composition ,

Provide information on unit cell dimensions

Basic Principles

Crystalline substances act as three-dimensional diffraction

gratings for X-ray wavelengths similar to the spacing of planes in a

crystal lattice (Max von Laue, 1912).

Based on constructive interference of monochromatic X-rays and a

crystalline sample.

The interaction of the incident rays with the sample produces

constructive interference (and a diffracted ray) when conditions

satisfy

Bragg's law: n λ = 2d sin 0

Nafila Khuzaimatun Nafi’ah
195160101111015

Production of X-rays

Cross section of sealed-off filament X-ray tube

X-rays are produced whenever high-speed electrons collide with a metal

target.

A source of electrons- hot W filament, a high accelerating voltage (30-

50kV) between the cathode (W) and the anode, which is a water-cooled

block of Cu or Mo containing desired target metal.

FUNDAMENTAL CONCEPTS SOLIDS

AMORPHOUS

Atoms in an amorphous

solid are arranged

randomly- No Order

CRYSTALLINE

Atoms in a crystalline solid

are arranged in a repetitive

three dimensional pattern

Long Range Order

All metals are crystalline solids

Many ceramics are crystalline solids

Some polymers are crystalline solids

Nafila Khuzaimatun Nafi’ah
195160101111015

What Is Diffraction?

A wave interacts with

A single particle

The particle scatters

the incident beam uniformly in

all directions.

A crystalline material

The scattered beam may add

together in a few directions

and reinforce each other to

give diffracted beams.

Constructive and Destructive

Interference of Waves

Constructive interference occurs only when the path difference of the scattered wave from consecutive
layers of atoms is a multiple of the wavelength of the x-ray.

Bragg's Law and X-ray Diffraction

How waves reveal the atomic structure of crystals

n λ 2dsin(0)

n-integer

Diffraction occurs only when Bragg's Law is satisfied Condition for constructive interference (X-rays 1 &
2) from planes with spacing d
Nafila Khuzaimatun Nafi’ah
195160101111015

Basics of Crystallography

smallest building block

A crystal consists of a periodic arrangement of the unit cell into a lattice. The unit cell can contain a
single atom or atoms in a fixed arrangement.

Crystals consist of planes of atoms that are spaced a distance

apart, but can be resolved into many atomic planes, each with a

different d-spacing.

a, b and c (length) and a, B and y (angles between a, b and c) are

lattice constants or parameters which can be determined by XRD.

Seven crystal Systems

System Axial lengths Unit cell and angles

Cubic

a=b=c

α = β = γ = 90°

Tetragonal

a=b#c

α = β = γ = 90°

Orthorhombic

a#b#c

α = β = γ = 90°
Nafila Khuzaimatun Nafi’ah
195160101111015

Rhombohedral

a=b=c

α = β = γ # 90°

Hexagonal

a=b#c

α = β = 90°

γ=120°

Monoclinic

a#b#c

α=γ=90°#β

Triclinic

a#b#c

α # β # γ # 90°

Miller Indices - hkl

Miller indices form a notation system in crystallography for planes in crystal lattices.

Miller indices-the reciprocals of the

fractional intercepts which the plane

makes with crystallographic axes

X-ray Diffraction Pattern

A multiphase sample. This sample was run more slowly than the others to get higher intensity, which
makes it easier to effectively identify many of the peaks. Major phases

include quartz, halite, clinochlore and either illite or muscovite.

Nafila Khuzaimatun Nafi’ah
195160101111015

XRD Pattern

Significance of Peak Shape in XRD

1.Peak position

2.Peak width

3.Peak intensity

Peak Width - Full Width at Half Maximum

(FWHM)

Determine

1. Particle or grain size

2. Residual strain

XRD patterns from other states of matter

Crystal

Constructive interference Structural periodicity

Diffraction Sharp maxima

Liquid or amorphous solid

Lack of periodicity Short range order

One or two broad maxima

Monatomic gas

Atoms are arranged perfectly at random

Scattering I

decreases with 0
Nafila Khuzaimatun Nafi’ah
195160101111015

Powder X-Ray Diffraction

(most widely used for polycrystals)

A powder sample is in fact an assemblage of small crystallites, oriented at random in space.

Detection of Diffracted X-ray

by A Diffractometer

• x-ray detectors (e.g. Geiger counters) is used instead of

the film to record both the

position and intensity of the

x-ray peaks

• The sample holder and the x-

ray detector are mechanically

linked

•If the sample holder turns 0,

the detectar turns to 20, so that

the detector is always ready to

detect the Bragg diffracted

x-ray

Phase Identification

(One of the most important uses of XRD)

ㆍObtain XRD pattern

ㆍMeasure d-spacings and integrated

intensities (dI list)

ㆍ Compare data with known standards in the JCPDS/ICDD files (> 200,000 files).
Nafila Khuzaimatun Nafi’ah
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JCPDS Card

1. File number

2. 3 strongest lines

3. Lowest-angle line

4. Chemical fomula and name

5. Data on diffraction method use

6. Crystallographi data

7.Optical and other data

8. Data on specimen

9. Data on diffraction pattern.

Joint Committee on Powder Diffraction Standards, JCPDS (1969)

Replaced by the International Centre for Diffraction Data,ICDD (1978)

ICDD Databases contain dI lists for thousands of crystalline phases.

- The PDF contains more than 200,000 diffraction patterns.

- Modern computer programs can help you determine what phases are

present in your sample by quickly comparing your diffraction data to all

of the patterns in the database.

- The PDF card for an entry contains a lot of useful information, including

literature references.

Advantages

- Powerful and rapid (< 20 min) technique for identification of an unknown inorganic materials

- In most cases, it provides an unambiguous mineral determination

- Minimal sample preparation is required

- XRD units are widely available

- Data interpretation is relatively straight forward

Nafila Khuzaimatun Nafi’ah
195160101111015

Disadvantages

- Homogeneous and single phase material is the best for identification of an unknown

- Must have access to a standard reference file of inorganic compounds (d- spacings, hkls)

- Requires tenths of a gram of material which must be ground into a powder

- For mixed materials, detection limit is ~ 3% of sample

- For Unit cell determinations, indexing of patterns for non-isometric cryst is complicated

- Peak overlay may occur and worsens for high angle 'reflections'

PXRD Characterisation for Nanomaterials

1. Pure phase determination

2. Confirmation of the present of host-guest phases

3. Host-guest interactions; intercalation, exfoliations, etc.

4. Nanostructures formation: eg. 2D-layered structure,

nanoparticles, etc.

Applications of XRD

(a nondestructive technique)

- To identify crystalline phases

- To determine structural properties:

Lattice parameters (1048), strain, grain size,

phase composition, preferred orientation, order-disorder

transformation, thermal expansion, etc.

- To measure thickness of thin films and multilayers

- To determine atomic arrangement

- To image and characterize defects

Nafila Khuzaimatun Nafi’ah
195160101111015

Detection limits:

~3% in a two phase mixture

~0.1% with synchrotron radiation.

Allotropy or allotropism

ㆍMaterials.of the same chemical elements but exist in two or more different atomic arrangements.

ㆍ The atoms of the element are bonded together in a different manner.

SPATIAL ORIENTATION OF THE DRUG MOLECULES

IN THE LAYERED INORGANIC INTERLAMELLAE

Depends on

a. The size of the guest (ChemOffice)

b. Spatial orientation of the guest (XRD data and (a))

Application of XRD Pattern

(a) Zn-Al-LDH before thermal treatment and Zn-Al-LDH at calcined temperature range of 50, 100 and
150 *C, with (*) ZnO phase.

(b) Zn-Al-LDH at calcined temperatures of 200, 250 and 300 ㆍC. The small black square represents the
LDH phase after calcination above 150 ㆍC.

Quantitative Phase Analysis

To determine how much of each phase is present (with high quality data) The ratio of peak intensities
varies linearly as a function of weight fractions for any two phases in a mixture (assumption: constant
volume)

Whole pattemn fitting/Rietveld

refinement is a more accurate

but more complicated analysis

Nafila Khuzaimatun Nafi’ah
195160101111015

Unit Cell Lattice Parameter Refinement

Determination of the unit cell lattice parameters of the phases

(by accurately measure peak positions over a long range of 20)

- alloying, substitutional doping, temperature and pressure, etc., create changes in lattice parameters
(can be quantify)

- use many peaks over a long range of 20 - so that we can identify and correct for systematic errors such
as specimen displacement and zero shift

- measure peak positions with a peak search algorithm or profile fitting

- profile fitting is more accurate but more time consuming then numerically refine the lattice parameters

eg. HighScore Plus software (PANanalytical)

- Comprehensive phase identification program

- Profile fitting

- Rietveld analysis

- Crystallographic analysis

- Instant candidate match

- Automatic identification

- Strain & size analysis

Hydroxyapatite: also called hydroxylapatite (HA/HAP)

Naturally occurring mineral: calcium apatite

Formula: Ca5(PO4)6(OH)2

Usually written: Ca10(PO4)6(OH)2

(to denote that the crystal unit cell comprises 2 unit formula).

HA - hexagonal crystal system.

Up to 50% by volume and 70% by weight of human bone is a modified form of hydroxyapatite, known as
bone mineral.
Nafila Khuzaimatun Nafi’ah
195160101111015

The main mineral for DENTAL ENAMEL AND DENTIN is carbonated calcium-deficient HA

Rietveld refinement of the diffraction pattern collected from the sample T38. Crosses

mark the experimental data, the continuous line is the calculated HA pattern, the vertical

ticks mark the calculated Bragg peaks, and the lower trace shows the difference between

observed and calculated patterns.

Take home keywords

- XRD, PXRD, diffraction, constructive interference

- Bragg's Equation (n入=2dsin 0)

Scherrer's equation

- Amorphous/Crystalline/Miller indices/polycrystals

- XRD pattern and FWHM

- Phase identification, JCPDS, ICDD

- X-ray diffractometer/goniometer

- Sample preparation

- Application of PXRD

- Advantages/disadvantages

- Examples of PXRD characterisation for nanomaterials