In the name of Allah Assistance prof. Dr. - PowerPoint Presentation

Slide1

In the name of

Allah

Assistance prof. Dr.

Luma

Majeed

Ahmed

Fundamentals of XRD as Nanotechnology

instruments

lumamajeed2013@gmail.com, luma.ahmed@uokerbala.edu.iq

3

(

under Max Planck and

Sommerfeld

)

In

1912

, von

Laue

discovered the

diffraction

of X-rays

by crystals and won the Nobel Prize in Physics in 1914.

In

1895, Wilhelm Rontgen discovered X-rays. He won the Nobel Prize in Physics in 1901.(the range is 0.101 – 10 nm)

From Wikipedia

A Brief History of XRD

4

in

1912 the

Braggs

,

father

and son

, experimentally discovered the

Bragg law of

the

X-ray

diffraction.

Bragg’s X-ray experiment led to the

discovery of the structure of DNA in 1953.Reported a book (x-rays and crystal structure) in 1915.

Sir William H. Bragg

(1862-1942)Sir William L.  Bragg(1890-1971) 1918: Paul Scherrer uses X-Rays to determine crystallite size of nan-ocrystalline gold.

Paul Scherrer (1890–1969)

Law describing the

necessary condition

for diffraction

Applicable for

photons

,

electrons

and

neutrons

n: integer

Bragg’s law

Condition for efficient specular reflection

(

click for java applet

)

Bragg Diffraction Law

1

3

4

2

http://prism.mit.edu/xrayThe Scherrer

Equation was published in 1918Peak width (B) is inversely proportional to crystallite size (L)B must transfer from degree to radians by multiply to

when did

Scherrer

use X-rays to estimate the crystallite size of nanophase materials?

L

= thickness of crystallite

K

= constant dependent on

crystallite(grain)

shape (0.94) is spherical(0.90) is tube or rode(0.89 or 0.85) is wire or any other shape.l = x-ray wavelength (0.15406 nmB = FWHM (full width at half max) or integral breadthqB = Bragg Angle

Scherrer’s FormulaUses of X-ray Powder Diffraction

Data Analysis

d

=

λ

/ (2 Sin

θ

B

)

λ

= 1.54 Ǻ, 2

θ

=38.3 = 1.54 Ǻ / ( 2 * Sin ( 38.3 / 2 ) ) = 2.35 ǺSimple Right!Bragg Example

L = 0.89*λ / (B Cos θB) = 0.89*1.54 Ǻ / ( 0.00174 * Cos (98.25/ 2 ) ) = 1200 Ǻ B = (0.100)x π/180 = 0.00174

Simple Right!Scherrer’s Example

λ = 1.54 Ǻ

Q/calculate the mean crystal size for TiO

2 crystal for XRD chart, where. λ= 0.15406 nm, note the crystal is spherical

L=

(111)

Thank you

For your Attention