XRD basics

1. X-Ray &
X-ray diffraction
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History: Discovery of X-ray
 Wilhelm Conrad Röntgen, Professor of Physics, University of Würzburg, Germany
discovered the X-rays on 8th November, 1895. In 1901, he was honoured by the Noble prize
for physics. In 1995, the German Post edited a stamp, dedicated to W.C. Röntgen.

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 X-ray is an electromagnetic radiation with wavelength in
the range 0.1-100 Å (0.01-10 nm)
What is X-ray ?

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X-ray wavelength ranges

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Why are X-ray so useful ?

6. Production of X-rays
X-rays are produced by bombarding a metal target
(Cu, Mo usually) with a beam of electrons emitted
from a hot filament (often tungsten). The incident
beam will ionize electrons from the K-shell (1s) of
the target atom and X-rays are emitted as the
resultant vacancies are filled by electrons dropping
down from the L (2p) or M (3p) levels.
This gives rise to Kα and Kβ lines.

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The Principles of an X-ray Tube
Anode
focus
Fast electrons
Cathode
X-Ray

8. The Principle of Generation the
Characteristic Radiation
K-Quant
L-Quant
K-Quant
K
L
M
Emission
Photoelectron
Electron

9. The Generating of X-rays
Bohr`s model

10. The Generating of X-rays
M
K
L
K K K K
Energy levels (schematic) of the electrons
Intensity ratios
KKK
Emission Spectrum of a Molybdenum X-
Ray Tube

11. The Generating of X-rays
Anode
Mo
Cu
Co
Fe
(kV)
20,0
9,0
7,7
7,1
Wavelength Angström
K1 : 0.70926
K2 : 0.71354
K1 : 0.63225
Filter
K1 : 1.5405
K2 : 1.54434
K1 : 1.39217
K1 : 1.78890
K2 : 1.79279
K1 : 1.62073
K1 : 1.93597
K2 : 1.93991
K1 : 1.75654
Zr
0,08mm
Mn
0,011mm
Fe
0,012mm
Ni
0,015mm

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Introduction/ Principle
X-ray diffraction (XRD) is a non-destructive
technique that operates on the nanometre scale
based on the elastic scattering of X-rays from
structures that have long range order (i.e. an
organised structure of some sort, e.g. periodicity,
such as in a crystal or polymer).
It can be used to identify and characterise a diverse
range of materials, such as metals, minerals,
polymers, catalysts, plastics, pharmaceuticals,
proteins, thin-film coatings, ceramics and
semiconductors.

13. Theoretical Considerations
Solid matter can be described as :
Amorphous : The atoms are arranged in a
random way similar to the disorder we find in a
liquid. Glasses are amorphous materials.
Crystalline : The atoms are arranged in a
regular pattern, and there is as smallest volume
element that by repetition in three dimensions
describes the crystal.
About 95% of all solids can be described as
crystalline.
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14. Diffraction angle (2) →
Intensity
→
90 180
0
Crystal
90 180
0
Diffraction angle (2) →
Intensity
→
Liquid / Amorphous solid
Schematic of difference between
the diffraction patterns of various phases