Earth & Planetary Science Applications
of X-Ray Diffraction: Advances Available
for Research with our New Systems
James R. Connolly
Dept. of Earth & Planetary Sciences
University of New Mexico
401/501 Colloquium
November 11, 2011
Outline
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What can you do with X-ray Diffraction?
X-Ray Powder Diffraction – Introduction to the method
Advances in X-ray detectors
Our Current Scintag system – strengths and weakness
Our New systems (arriving January) – new capabilities
Details of our New Systems (as time allows at end)
Acknowledgements: Thanks to Aya Takase, Al Larsen, and
Sean Bird from Rigaku, USA, for help with technical graphics,
Maarten DeMoor for use of his sample data, the National
Science Foundation for funding our new instruments, and CoPIs
Adrian Brearley, Abhaya Datye and Darren Dunphy for making it
all happen.
What can you do with X-ray Diffraction?
• Identify crystalline materials in powdered samples
• Determine of amounts of major and minor phases in multi-phase
samples +
• Obtain precise crystal structure data for phases in powders +
• Analyze most materials totally non-destructively
• Identify crystalline materials in thin coatings on natural or
engineered materials *
• Obtain good quality crystallographic data on extremely small
amounts of material *
• Analyze materials in controlled environments (oxygen-free,
controlled gas, controlled temperature) *
• Perform real-time experiments with materials under controlled
conditions *
• Identify phases in a non-destructive manner in intact small samples *
* Indicates capabilities to be added with our new systems
+ Indicates capability greatly enhanced with our new systems
What can’t you do with X-ray Diffraction?
• Identify trace amounts of phases in a multi-phase sample –
though new instruments can detect smaller amounts of
material, trace amounts are difficult to impossible to detect
• Quantitatively determine amounts of amorphous material in a
sample – this can be done by “difference” with an internal
standard but does not leave original material unaltered
• Do single-crystal diffraction analysis (though this capability can
be added to one of our new systems as an option)
• Do direct chemical analysis of samples – XRD can do
crystallographic analysis NOT chemical analysis
Diffraction patterns contains two “components”:
• Peak position provides information about crystal
structure or “d-spacings” in a crystalline phase
• Peak intensity provides information about the
scattering power of those “d-spacings”; this is in turn
related to the arrangements of constituent atoms in
the structure and abundance of phases in a mixture
• Lots of other information may be obtained from peak
shape and symmetry
The Bragg Equation
n  2d sin 
where n is an integer
 is the wavelength of the x-rays
d is the interplanar spacing in the specimen
 is the diffraction angle
•The Bragg equation is the fundamental diffraction equation
• It is used to calculate interplanar spacings in crystal structures
• It is valid only for monochromatic X-rays.
Intensity Scale
An XRD Data Plot: 2 (x-axis) vs. intensity (y-axis)
2 Angular Scale
Adding Peak Intensity Information to Positions
• Different diffraction peaks show differing
intensities
• Scattering occurs at the atomic level
• Intensities are related to how all of the scattered
X-rays from atoms in a particular diffracting “dspacing” add as a vector sum
• The combination of position and intensity is used
to “fingerprint” particular crystalline structures
(and often but not always unique phases)
Detector
Source
Monochromator
Specimen
An XRD Data Plot: 2 (x-axis) vs. intensity (y-axis)
Search/Match: Results Display
Search/Match: Printout of Results
X-ray Diffraction Patterns
Gas
Liquid /
amorphous
Powder /
polycrystalline
Single crystal
Extracting Information from a diffraction pattern
Whole pattern  Phase identification, quantitative analysis
Peak position  Lattice parameters
Peak width  Crystallite size & strain
Diffraction
Amorphous scattering
%Crystallinity
Background
Phase identification
Differing Intensity from strong preferred orientation
“Hump” in background indicates
presence of amorphous material
Our Existing Scintag Pad V System
• Sturdy, solid, reliable, good quality data
• Point detector collects data in 0.01° to 0.05° steps – avg.
data collection times 1-2 hours per sample; overnight for
high resolution (quantitative-capable) data
• One sample at a time (no sample changer)
• Cannot change parts easily – limited to Cu X-ray source,
single sample stage, point detector, -2 “BraggBrentano” scans
• Alignment is a several-day affair
• Analytical Software (DataScan4 & Jade+) good but not
well integrated with instrument
• State-of-the-art system in 1985; upgraded but limited by
its age
Laboratory Needs
• EPS XRD Lab is a service center used by multiple departments
on campus including: E&PS, Various Engineering Departments
and Institutes including CE, ChNE, CMEM, CHTM, Chemistry,
Anthropology, Pharmacy, Biology, Water Resources Program
• New System requirements:
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Easily reconfigurable for different analytical needs
Operable by non-experts in XRD
Easy, automated alignment after exchange of components
Add new research capabilities including:
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High throughput for standard powder analyses
Microdiffraction (phase identification from very small areas)
Non-ambient (atmosphere, controlled temperature & pressure) experiments
High-speed data collection (for real-time experiments)
Data collection from wet or damp materials
Low-angle data from films and coatings
Small angle scattering (SAXS) analysis for nano-materials
New Systems to Arrive January 2012
• Funded by NSF MRI Grant to CMEM (ChNE) and E&PS
• To best meet diverse needs of investigators, we opted for two
new instruments:
– Rigaku SmartLab Multi-purpose diffractometer capable of:
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Automated, multi-sample analysis w. sample spinning option
0D (Point) or 1D High Speed detector
Non-ambient (elevated T, controlled environment) experiments
Focused (parallel) X-ray beam or divergent beam geometry
Horizontal sample orientation (low-volume and wet samples ok)
Glancing Incidence, SAXS, GISAXS, HiRes XRD capabilities and more
– Rigaku Rapid II
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Small area-micro-diffraction w. large 2D detector
Work with very small amounts of powder or intact samples
Obtain diffraction data with highly oriented crystalline material
Standard powder diffraction (when other systems busy)
Rigaku SmartLab
Rigaku D-Max Rapid II
3-Dimensional Diffraction Space
Powder Sample
Advances in X-Ray Detectors
• Point or “0d” detectors have a limited “view” of diffraction space – one
point at a time, usually 0.2 to 0.5°
• Data collection is by fixed time at
each point, usually ½ to several
seconds, thus slow
• If lines are “spotty” because of
preferred orientation, diffractions
will be missed
• Most common 0d detector is the
Scintillation counter -- still widely
used for many applications
• Most efficient if used with a sample
changer in unattended mode
Advances in X-Ray Detectors
• Linear or 1d Detectors sample a larger angular slice of diffraction space,
usually 1-3° (but to 120° with specialized detectors)
• Moves through a range of diffraction
space as a “sliding window” collecting
data throughout its angular range
• Results in greatly increased speed of
data collection (typically 50x to 100x
that of a scintillation counter)
• Most modern 1d detectors are some
form of Silicon strip technology and
are very durable and robust devices
Rigaku D/teX Ultra 1d Detector
Linear range of diffraction space (up to 1.5°) measured simultaneously =
50-100x faster data collection
D/teX Ultra
Zeolite sample measured in 60 seconds
Variable temperature XRD experiment with D/teX Ultra Detector
Advances in X-Ray Detectors
• Area or 2d detectors view a substantial “slice” of diffraction space in
two dimensions
• Smaller 2d detectors can be moved
through diffraction space and images
combined to produce large map of
2d space
• Larger 2d detectors can remain fixed
recording a “snapshot” of 2d space
• 2d detectors enable collection of
diffraction data from samples with
extreme preferred orientation –
in some cases collecting useful data
from single crystals
Rigaku Rapid II Microdiffraction Advantages
• Extremely large detector (25.6 x 46.6 cm)
• Image plate records all X-ray energies – different
sources (Cu, Co, and Mo) may be used.
• Sources are easily changed
• 3-axis sample stage allows many different sample
types to be mounted and analyzed
• Beam collimators cover range from 800 µm to 30 µm
• Image recording times can be from 5 to 60 minutes
(or more if needed)
• Image is digitally read, data recorded and plate ready
for reuse within a couple of minutes
Meteorite ALH 84033 – Microdiffraction Data from Rigaku Rapid II
“Black” area
Meteorite ALH 84033 – Microdiffraction Data from Rigaku Rapid II
“Brown” area
Meteorite ALH 84033 – Microdiffraction Data from Rigaku Rapid II
“White” area
Using the XRD Lab
• XRD lab is open to any faculty, students or staff wanting to
incorporate XRD in their research
• Radiation safety training and exam must be completed by all
users
• Training for equipment operation will be available
• The lab is a service center so fees are charged for use
• Fee schedules for analyses will be similar to that for the
current instrument with additional schedules for use of new
experimental equipment
• Anyone wanting to incorporate XRD into research proposals
should connect with me about how best to do that