X ray crystallography

X-RAY
DIFFRACTION
Presented by: Mukul S. Tambe.
Sem. I M. Pharm
(Pharmacology)
Roll No.: 8
10/10/2017
1

CONTENTS:
 Introduction
 Origin of x-rays
 Basic aspects of crystals
 Miller indices
 X-ray crystallography
 Methods of XRD
 Applications
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INTRODUCTION:
 It is a novel and non-destructive method of
chemical analysis and variety of X-ray techniques
are available now a days in practice.
 Different techniques: X-ray Absorption
X-ray Diffraction
X-ray Fluorescence
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ORIGIN OF X-RAYS:
 EM Radiations
 Wavelength: 0.01 to 10nm.
 Frequency: 30 petaHz to 30 exaHz.
 Energy: 100eV to 100keV.
 Sources:
1. Production by electrons
2. Production by fast positive ions
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*Ref:Chatwal,Pg.no.2.303

BASIC ASPECTS OF
CRYSTALS:
 Unit cell:
 Length of cell edges
 Angles between them
 Position off atoms in unit cells
 Crystal lattice:
Triclinic Monoclinic Orthorhombic
Tetragonal Hexagonal Cubic
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*Ref:Wikipedia-crystalstructure

MILLERS INDICES:
 Denoted by h, l, k values
 Helps to understand the
dimensions of cube
 Equation:
 d= spacing between
adjacent lattice
 a= lattice constant
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*Ref:Wikipedia:MillerIndices

X-RAY DIFFRACRTION:
 Principle:
“When X-ray are passed on crystal, they get
scattered based on the arrangement of atoms in
crystal.”
“Every crystalline substance gives a pattern; the
same substances always gives same pattern; and in
mixture of substance, each produce it’s pattern
independent of other.”
 Definition:
 The atomic planes of crystals cause an incident beam of X-
rays to interfere with one another as they leave the crystal.
This is called as XRD.
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*Ref:Chatwal-2.303;Willards-340

PRINCIPLE (CONTD.):
 Bragg’s Equation:
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*Ref:Chatwal2.309

BRAGG’S EQUATION:
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INSTRUMENTATION:
 Source of X-ray
 Collimator
 Monochromator
 Sample holder
 Detector
 Recorder
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1. SOURCE OF X-RAY:
Copper, Aluminium
Molybdenum
(10-60 kV)
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2. COLLIMATOR:
Used to narrow the beam of Particles/ Waves.
3. MONOCHROMATOR:
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4. SAMPLE HOLDER
 Sample Preparation:
 Ideally only 1 crystal (area of cross section= 0.3mm)
 For polycrystalline comp. / Powders (area of cross section= 0.002mm to 0.005mm)
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http://www.slideshare.net/gopinathkarnam/x-
ray-diffraction-25472126

5. DETECTORS:
 Photographic Detector
 Counter Detector
 Geiger Muller Tube Detector
 Proportional Counter
 Scintillation Detector
 Solid State semiconductor Detector
 Semiconductor Detector
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1. PHOTOGRAPHIC DETECTOR:
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2. COUNTER DETECTORS:
1. Geiger Muller Tube Detector:
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2. COUNTER DETECTORS (CONTD.):
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3. Scintillation Detector:
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4. Semiconductor Detector:

DIFFERENT METHODS OF XRD:
1. Laue method
2. Bragg’s X-ray Spectrophotometer
3. Rotating crystal method
4. Powder method
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1. LAUE METHOD
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 Single crystal is held stationary in a beam of X-ray or
neutron radiation of continuous wavelength
 Crystal selects out and diffracts the discrete values of θ
for which planes exist of spacing d and incidence angle
λ
 Method is convenient for the rapid determination of
crystal orientation and symmetry.
*Ref:Chatwal-2.318

2. BRAGG’S X-RAY SPECTROPHOTOMETER
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X-rays
Pass from slits
Falls on C
(Vertically rotating about it’s axis)
Reflected beam pass to Ionization chamber
Ionization of gas
Current measured by Galvanometer
Intensity of reflected X-ray is measured.
 The ionization current is measured for
different values of glancing angle θ. A
graph is drawn between the glancing angle
θ and ionization current.
*Ref:Chatwal-2.319

2. BRAGG’S X-RAY SPECTROPHOTOMETER
(CNTD):
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 For certain values of glancing
angle, the ionization current
increases abruptly.
 The first peak corresponds to
first order, the second peak to
second order and so on. From
the graph, the glancing angles
for different orders of reflection
can be measured.
 Knowing the angle θ and the
spacing d for the crystal,
wavelength of X–rays can be
determined
*Ref:Chatwal-2.319

3. ROTATING CRYSTAL TECHNIQUE
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 Crystal is rotated about fixed
axis.
 Variation in angle θ
 Dimensions of crystal <1mm
 The beam is diffracted from a
given crystal plane whenever
in the course of rotation the
value of θ satisfies the Bragg
equation.
 Beams from all planes parallel
to the vertical rotation axis will
lie in the horizontal plane.
Planes with other orientations
will reflect in layers above and
below the horizontal plane.
*Ref:Chatwal-2.324

4. POWDER METHOD:
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 The incident monochromatic radiation strikes a finely
powdered specimen or a fine grained polycrystalline
specimen contained in a thin walled capillary tube.
 Diffracted rays go out from individual crystallites which
happened to be oriented with planes making an incident
angle θ with the beam satisfying the Bragg equation.
 This method is known to be the most fast and accurate for
the determination of lattice constants.
*Ref:Chatwal-2.324

4. POWDER METHOD (CNTD):
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 X-ray powder diffraction is most widely used for the
identification of unknown crystalline materials (e.g. minerals,
inorganic compounds). Determination of unknown solids is
critical to studies in geology, environmental science,
material science, engineering and biology. Other
applications include:
 Characterization of crystalline materials
 Identification of fine-grained minerals such as clays and
mixed layer clays that are difficult to determine optically
 Determination of unit cell dimensions
 Measurement of sample purity
 With specialized techniques, XRD can be used to:
 Determine crystal structures using Rietveld refinement
 Determine of modal amounts of minerals (quantitative analysis)
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APPLICATIONS:
*Ref:Chatwal-2.326,Willards:370

PHARMACEUTICAL APPLICATIONS
(R&D):
 Crystal characterization of Acrinol
 Compaction Characteristics of bulk crystalline powders
 Polymorphism of Piracetam
 Evaluation of physical stability of Amoxicillin Trihydrate.
 Detection of solvatomorphism
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*Ref:Chatwal-2.326,Willards:370

REFERENCES:
1. Instrumental Methods of Analysis by Willard, Merritt, Dean,
Settle, CBS Publishers & Distributors, 7th Edition, Page No.
340 – 397
2. Instrumental Methods of Chemical Analysis by Gurdeep R.
Chatwal & Sham K. Anand, Himalaya Publications, 5th revised
edition, Page no. 2.303 – 2.339
3. http://www.slideshare.net/gopinathkarnam/x-ray-diffraction-
25472126
4. https://en.wikipedia.org/wiki/Crystal_structure#Unit_cell
5. http://serc.carleton.edu/research_education/geochemsheets/te
chniques/XRD.html
6. http://ictwiki.iitk.ernet.in/wiki/index.php/Unit-
2:_Introduction_to_X-ray_diffraction#ROTATING-
CRYSTAL_METHOD
7. Lecture 1.pdf
8. Han J, Suryanarayanan R. A method for the rapid evaluation of
the physical stability of pharmaceutical hydrates.
Thermochimica acta. 1999 Apr 26;329(2):163-70.
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REFERENCES OF RESEARCH
ARTICLES:
1. Brittain HG. X-ray diffraction of pharmaceutical materials. Profiles of
Drug Substances, Excipients and Related Methodology. 2003 Dec
31;30:271-319.
2. Han J, Suryanarayanan R. A method for the rapid evaluation of the
physical stability of pharmaceutical hydrates. Thermochimica acta. 1999
Apr 26;329(2):163-70.
3.Moore MD, Steinbach AM, Buckner IS, Wildfong PL. A structural
investigation into the compaction behavior of pharmaceutical
composites using powder X-ray diffraction and total scattering analysis.
Pharmaceutical research. 2009 Nov 1;26(11):2429-37.
4. Croker DM, Hennigan MC, Maher A, Hu Y, Ryder AG, Hodnett BK. A
comparative study of the use of powder X-ray diffraction, Raman and
near infrared spectroscopy for quantification of binary polymorphic
mixtures of piracetam. Journal of pharmaceutical and biomedical
analysis. 2012 Apr 7;63:80-6.
10/10/2017
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