XRD talk for Ph.D student-09.01.2024.pdf

XRD basics

1. X-Ray &
X-ray diffraction
1

2. 2
History: Discovery of X-ray
Wilhelm Conrad Röntgen, Professor of Physics, University of Würzburg, Germany
discovered the X-rays on 8
th
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.

3. 3
X-ray is an electromagnetic radiation with wavelength in
the range 0.1-100 Å (0.01-10 nm)
What is X-ray ?

4. 4
X-ray wavelength ranges

5. 5
Why are X-ray so useful ?

6. Production of X-rays
X-raysareproducedbybombardingametaltarget
(Cu,Mousually)withabeamofelectronsemitted
fromahotfilament(oftentungsten).Theincident
beamwillionizeelectronsfromtheK-shell(1s)of
thetargetatomandX-raysareemittedasthe
resultantvacanciesarefilledbyelectronsdropping
downfromtheL(2p)orM(3p)levels.
ThisgivesrisetoK
αandK
βlines.

7. 7
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

12. 12
Introduction/ Principle
X-raydiffraction(XRD)isanon-destructive
techniquethatoperatesonthenanometrescale
basedontheelasticscatteringofX-raysfrom
structuresthathavelongrangeorder(i.e.an
organisedstructureofsomesort,e.g.periodicity,
suchasinacrystalorpolymer).
Itcanbeusedtoidentifyandcharacteriseadiverse
rangeofmaterials,suchasmetals,minerals,
polymers,catalysts,plastics,pharmaceuticals,
proteins,thin-filmcoatings,ceramicsand
semiconductors.

13. Theoretical Considerations
Solidmattercanbedescribedas:
Amorphous:Theatomsarearrangedina
randomwaysimilartothedisorderwefindina
liquid.Glassesareamorphousmaterials.
Crystalline:Theatomsarearrangedina
regularpattern,andthereisassmallestvolume
elementthatbyrepetitioninthreedimensions
describesthecrystal.
About95%ofallsolidscanbedescribedas
crystalline.
13

14. Diffraction angle (2)→
Intensity
→
90 1800
Crystal
90 1800
Diffraction angle (2)→
Intensity
→
Liquid / Amorphous solid
Schematic of difference between
the diffraction patterns of various phases