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X ray
Author:
Md. Waliullah Wali
Dept. of pharmacy
Southeast University
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Outline
X-ray diffraction
Limitations of XRD
Principles of XRD
XRD Techniques
Applications of XRD
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Advantages & Limitations of XRF
Principles of XRF
XRF Techniques
Applications of XRF
X-Ray Fluorescence
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XRD
X-ray diffraction (XRD) is an analytical technique
looking at X-ray scattering from crystalline
materials. Each material produces a unique X-ray
"fingerprint" of X-ray intensity versus scattering
angle that is characteristic of it's crystalline atomic
structure.
X-ray diffraction procedures
apply only to crystalline
Materials.
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Principles of XRD
X-ray diffraction is based on constructive
interference of monochromatic X-rays and a
crystalline sample.
The interaction of the incident rays with the sample
produces constructive interference (and a diffracted
ray) when conditions satisfy Bragg's Law (nλ=2d sin
θ).
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XRD Techniques
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XRD Techniques
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2
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Applications of XRD
Determine crystal
structures Determine of modal amounts
of minerals
Make textural measurements
-Characterization of
crystalline materials
-Identification of fine-
grained minerals
-Determination of unit cell
dimensions
-Measurement of sample
purity
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Limitations of XRD
Homogeneous and
single phase
material is best
For mixed
materials,
detection limit
is ~ 2% of
sample Peak overlay may
occur and worsens
for high angle
'reflections' Requires tenths of a
gram of material
which must be
ground into a powder
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XRF
X-Ray Fluorescence is defined as “The emission of
characteristic "secondary" (or fluorescent) X-rays
from a material that has been excited by
bombarding with high-energy X-rays. The
phenomenon is widely used for elemental analysis.”
X-ray fluorescence procedures
applied to the material
in any physical state,
solid, liquid and gas.
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Principles of XRF
The XRF method depends on fundamental principles that are common to several other instrumental methods involving interactions between electron beams and X-rays with samples, including, X-ray spectroscopy (e.g. SEM – EDS), X-ray diffraction (XRD) and wavelength dispersive spectroscopy (microprobe WDS).
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XRF Techniques
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Applications of XRF
Bulk chemical analyses of major elements
(Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P) in
rock and sediment
Bulk chemical analyses of trace elements
(in abundances >1 ppm; Ba, Ce, Co, Cr,
Cu, Ga, La, Nb, Ni, Rb, Sc, Sr, Rh, U, V,
Y, Zr, Zn) in rock and sediment
-Research in igneous,
sedimentary, and metamorphic
petrology
-Soil surveys
-mining
-Cement production
-Ceramic and glass
manufacturing
-Environmental studies
-Petroleum industry
-Field analysis
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Advantages of XRF
Minimal
preparation Non-
destructive
Fast
Easy to
use
Cost-
effective
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Limitation of XRF
0 Relatively large
samples, typically >
1 gram
Materials that can be
prepared in powder form
and effectively
homogenized
Materials for which
compositionally similar,
well-characterized
standards are available Materials containing high
abundances of elements for which
absorption and fluorescence effects
are reasonably well understood
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References
1. Elements of physical chemistry by S Glasstone
2. Atkins physical chemistry
3. Pharmaceutical chemistry by LG Chattem
4. Brady, John B., and Boardman, Shelby J., 1995, Introducing
Mineralogy Students to X-ray Diffraction Through Optical
Diffraction Experiments Using Lasers. Jour. Geol. Education, v.
43 #5, 471-476.
5. Brady, John B., Newton, Robert M., and Boardman, Shelby J.,
1995, New Uses for Powder X-ray Diffraction Experiments in the
Undergraduate Curriculum. Jour. Geol. Education, v. 43 #5, 466-
470.
6. Buhrke, V. E., Jenkins, R., Smith, D. K., A Practical Guide for
the Preparation of Specimens for XRF and XRD Analysis, Wiley,
1998.
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Thank All of you!
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