X-ray crystallography is a technique used to determine the atomic and molecular structure of crystals. It works by firing X-rays at crystalline samples and observing the scattering pattern. Bragg's law describes how the scattering pattern can reveal the distances between planes of atoms in the crystal. There are several methods for X-ray crystallography including powder diffraction. X-ray diffraction has many applications such as determining crystal structures, identifying unknown compounds by comparing to databases, and characterizing materials like polymers. Crystals can be categorized based on their structure into 7 crystal systems or by their chemical properties as covalent, ionic, or metallic crystals.

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X-RAY
CRYSTALLOGRAPHY
Presented by,
SONU BENNY
M.Pharm
Dept of Pharmaceutical Chemistry

3. X-RAY POWDER TECHNIQUE,
TYPES OF CRYSTALS &
APPLICATIONS OF X-RAY
DIFFRACTION
3
X-RAY
CRYSTALLOGRAPHY

4. CONTENTS…4
 Introduction
 X-Ray Powder Technique
 Types of Crystals
 Applications of Powder Diffraction
 Conclusion
 Reference

5. INTRODUCTION...
5
 X-Rays are
 Electromagnetic radiation
 Wavelength range-0.1 to 100A0
 Discovered by Wilhelm Conrad Rontgen in 1895
 Energy of X-rays, given by Einstein’s equation:
E = h = hc/
 Higher energy than visible light, can penetrate matter easily.

7. X-RAY TECHNIQUES
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 X-RAY ABSORPTION METHOD – A beam of X-ray allowed
to pass through sample. The fraction of photons absorbed is a
measure of concentration
 X-RAY FLOURESCENCE METHOD – X-rays are generated
within the sample. By measuring its wavelength & intensity,
qualitative &quantitative analysis can be performed
 X-RAY DIFFRACTION METHOD – Based on scattering of
X-rays by crystals. Help to identify the crystal structure of many
solids

8. Applications of X-rays
8

9. APPLICATIONS
STRUCTURE OF CRYSTALS
 Non-destructive method
 Molecular structure and size of crystal planes
POLYMER CHARACTERISATION
 Degree of crystallinity of the polymer
 Ratio of area of diffraction peaks to scattered radiation is
proportional to the ratio of crystalline to noncrystalline
material
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10. STATE OF ANNEAL IN METALS
 Well annealed metals - sharp diffraction lines
 If subjected to hammering or bending - diffused diffraction
pattern
PARTICLE SIZE DETERMINATION
a) Spot counting method>5microns
b) Broadening of diffraction lines
 particles of the range 30 -1000Ao
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11. APPLICATION TO COMPLEXES
a)Determination of cis-trans isomerism
b)Determination of linkage isomerism
MISCELLANEOUS APPLICATIONS
a)Soil classification based on crystallinity
b)Analysis of industrial dusts
c)Assessment of degradation of natural and synthetic minerals
d)Study of corrosion products
e)Examination of tooth enamel and dentine
f)Effects of diseases on bone structure
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12. X-RAY DIFFRACTION
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 A technique where the compounds diffract (scatter) the X-
Rays of wavelength ranging from 10-6 to 10-10, based on the
inter atomic distance in a crystal. The resulting diffraction
pattern shows the arrangement of atoms within the crystal.

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14.  Used to characterize the
crystallographic structure,
crystallite size and preferred
orientation in polycrystalline or
powdered solid samples.
 To identify unknown substances,
by comparing diffraction data against a
database maintained by the
International Centre for
Diffraction Data.
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15. LATTICE - Representation of crystal
structure as an array of points in space
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NaCl crystal lattice

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The
fundamental
pattern of
minimum
number of
atoms or
molecules
which
represent the
full character
of the crystal.
UNIT CELL-

17. Parallel equi
distant planes
passing through
the lattice points
Parallel planes
of atoms
intersecting the
unit cell are used
to define
directions and
distances in the
crystal
LATTICE PLANES
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23. BRAGG’S LAW

25. X-RAY DIFFRACTION
METHODS
 Laue photographic method
 Bragg x-ray spectrometer method
 Rotating crystal method
 Powder diffraction method
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26. LAUE PHOTOGRAPHIC METHOD
 Transmission Laue method - The film is placed
behind the crystal to record beams which are
transmitted through the crystal
 Back-reflection method - The film is placed
between the x-ray source and the crystal. The beams
which are diffracted in a backward direction are
recorded
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27. TRANSMISSION METHOD
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28. BACK REFLECTION METHOD
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29. BRAGG’S SPECTROMETER METHOD
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30. ROTATING CRYSTAL METHOD
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X - ray
Powder
diffraction
(XRPD)

32. X ray Powder diffraction (XRPD)
 Rapid analytical technique for
phase identification of crystalline
materials & provide information on
unit cell dimensions
 Max Von Laue in 1912- crystalline
substances act as 3D diffraction
gratings for x-rays similar to spacing of
planes in a crystal lattice
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33.  XRPD is the most widely used X-ray diffraction
technique for characterizing materials.
 Common technique for study of crystal structures &
atomic spacing
 As the name suggests, the sample is usually in a powder
form, consisting of fine grains of single crystalline
material to be studied.
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34. Fundamental principles of X-ray powder
diffraction
 It is based on constructive interference of monochromatic
x-rays and a crystalline sample when conditions satisfy
Bragg’s law
W. H. Bragg W. L. Bragg
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35. X-RAY POWDER DIFFRACTION
 For phase identification of crystalline materials
 1 mg of the powder sample material is sufficient
 Unknown crystalline substances can be identified by
comparing the diffraction data with the data of
International Centre for Diffraction Data
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 The X-Ray beam is allowed to fall on the powdered
specimen through the slits and to get a narrow
pencil of X-Rays. Samples can be powder, sintered pellets,
coatings on substrates etc
 Fine powder struck on a hair by means of gums is
suspended vertically in the axis of a cylindrical camera.
This enables sharp lines to be obtained on the
photographic film which is surrounding the powder
crystal in the form of a circular arc.

38.  X-Ray after falling on the powder passes out of the
camera though a cut in the film so as to minimize the
fogging produced by scattering of the direct beam
 If the crystallites are randomly oriented, and there are
enough of them, then they will produce a continuous
Debye cone.
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39. X Rays striking a single crystal will produce diffraction
spots in a sphere around the crystal
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40. Powder diffraction pattern Radiation: Cu K,  = 1.54056 Å
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41. INFORMATIONS FROM XRPD
 Peak Position
 Crystal System
 Unit Cell Dimensions
 Qualitative Phase Identification
 Peak Intensity
 Unit Cell Contents
 Point Symmetry
 Quantitative Phase Fractions
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42. The Powder Diffraction File (PDF)
Material name
Strongest
peaks
Wave
length of
X-rays
System,
space
group
& cell
parame
ters
D or 2
Relative
intensity
Peak
assignmen
t
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43. Diffraction angle (2) →
Intensity→
90 1800
Imperfect
Crystal
90 1800
Diffraction angle (2) →
Intensity→
Liquid / Amorphous
solid
90 1800
Diffraction angle (2) →
Intensity→
Mono atomic gas
Nature of sample
Perfect Crystal
Intensity→
Diffraction angle (2) →
0 90 180
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Types
of
crystals

45. Crystals45
 Crystals get their structure from the way the
atoms within them bond together
 This causes a specific shape to appear as the crystal
grows larger.
 Scientists use the shape and the type of bonds
between the atoms to classify crystals.
 Crystal structures are referred to as crystal systems.

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 There's more than one way to categorize a crystal!
 The two most common methods are
 according to their crystalline structure
 according to their chemical/physical properties

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ACCORDING TO
CHEMICAL/PHYSICAL
PROPERTIES

48. Covalent crystals
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 Crystals whose atoms are connected with covalent
bonds.
 Covalent bonds exist where the atoms share electrons.
 These bonds are extremely strong and very hard to
break.
 Because of this, the crystals themselves are also very
strong and have high melting points
 Example : DIAMOND, one of the hardest substance
known to man

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Diamond and Graphite: Two Allotropes of Carbon: In diamond,
the bonding occurs in the tetrahedral geometry, while in graphite the
carbons bond with each other in the trigonal planar arrangement.

50. Ionic crystals
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 Crystals whose atoms are held together with ionic bonds,
or charged bonds.
 With these ionic bonds, one atom is negatively charged and
is attracted to other atoms in the crystal that are positively
charged.
 They are arranged in a pattern based on the charges.
 These crystals are typically hard solid with a relatively
high melting point.
 An example is table salt sodium chloride (NaCl).

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Halite, or rock salt, is the mineral form of sodium chloride. Halite forms cubic
crystals. It occurs in evaporite minerals that result from the drying up of enclosed
lakes and seas.

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 They conduct electricity in molten state and in the form of
solution.
 They are brittle
 not ductile
 can not be drawn into sheets

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54. Metallic crystals
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 Crystals made of metal elements.
 These crystals sparkle with the lustrous shine as that
of metals having.
 They are extremely good conductors of heat and
electricity.
 Copper can be extracted from copper crystals to form
copper wire used to transmit electricity in our homes.
 The melting point of these crystals depends on
the metal used in the crystal.
 Gold nuggets are an example of metallic crystals.

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Gold: Gold is a noble metal; it is resistant to corrosion and oxidation

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 In metallic crystals, atoms are joined together by metallic bond.
Metallic crystals are very hard.
 They have high melting point and boiling point
 They have shiny surface
 They conduct electricity and heat
 They are ductile
 They are malleable

58. Crystal systems58
There are 7 crystal systems in terms of crystal shapes and
lattice types.
 TRICLINIC - usually not symmetrical from one side to the
other, which can lead to some fairly strange shapes
 MONOCLINIC - like skewed tetragonal crystals, often
forming prisms and double pyramids

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 ORTHORHOMBIC - like tetragonal crystals except not
square in cross section (when viewing the crystal on end),
forming rhombic prisms or dipyramids (two pyramids
stuck together)
 TETRAGONAL - similar to cubic crystals, but longer
along one axis than the other, forming double pyramids
and prisms

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 HEXAGONAL - six-sided prisms. When you look at the
crystal on-end, the cross section is a hexagon
 CUBIC - characterized by equal sized sides and a cube-like
appearance. not always cube shaped! also find octahedrons
(eight faces) and dodecahedrons (10 faces).
 TRIGONAL - possess a single 3-fold axis of rotation
instead of the 6-fold axis of the hexagonal division

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Applications
of
XRD

62. Applications of XRD
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 Distinguishing Crystals: The diffraction obtained is
characteristic of particular compound from which the
crystals are formed.
 Mixture of Crystals, which gives different diffraction
pattern
 Mixed Crystals which give a separate diffraction pattern

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 Determination of complex structure of metal and alloys
 Identification of unknown crystalline compound:
 By using computer data base of modern instruments
 Compare the diffraction pattern with that of known
compound.

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 Polymer Characterization
 Used to determine the Crystallinity of the polymer
 The crystalline portion causes continuous diffraction
line
 Non- Crystalline portion simply scatter the X-Rays
beam to give continuous background

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 Elucidating the structure of the Compound
 Major tool in elucidating the structure of RNA & DNA
 Determination of Cis & Trans Isomer
 Soil classification based on Crystallinity
 gives informations concerning soil structure
 Accounts for the Effect of Rain and Drought

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 Degradation of Products
 used to asses weathering and degradation of natural and synthetic
material
 Factors responsible for degradation can be revealed
 Study of polymorphs by using X-Ray Diffraction
 X- Ray will helps to select the active form of the molecule during
molecule development

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 States of Anneals
 Annealed metals are the one in which crystal forms are well
arranged and give sharp diffraction lines
 This property of metal is lost when metal is fatigued (hammered,
drilled)
 XRD can Identify the fatigue of metal parts in aero plane, machines
or bridges
 for checking the moving parts for metal fatigue without removing
the part from its position.

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 To detect the Microscopical defects in a crystal
 X – Ray diffraction topography depends on image
contrast upon point to point change in direction or
intensity of the beam scattered by planes in the crystals
 Much used methods of XRD Topography are
 BERG – BERRETT METHOD
LANG METHOD

69. CONCLUSION
A powerful technique used to characterize the
crystallographic structure, crystallite size and
to identify unknown substances, by comparing
diffraction data against a database maintained
by the International Centre for Diffraction
Data.
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70. REFERENCES
1) Skoog, Holler, Niemann, Principles of Instrumental Analysis, 5th
edition, Page number:343-376
2) Instrumental Methods of Chemical Analysis Gurdeep.S.Chatwal,
Sham.K.Anand Page no.2.302-2.332
3) Instrumental method of analysis by Willard, Merritt, Dean, Settle 7th
Edition, Page number:372-376
4) Text book of Pharmaceutical Analysis by Dr. S Ravi Sankar, 4th
edition, Page Number: 34.1 – 34.
5) www.wikipedia.com
6) www.natural and applied science.com
7) www.sciencehq.com
8) www.citycollegiate.com
9) www.courses.lumenlearning.com
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