1. Scott Speakman 13-4009A x3-6887 speakman@mit.edu
The X-Ray SEF
Scott Speakman A
x3-6887

2. What Can You Do with XRD? Identify and Quantify Phase Composition
Rutile: P42/mnm
high temperature polymorph
white pigment, sunscreen,
UV-blocking coatings, photovoltaic
TiO2- Rutile
TiO2- Anatase
TiO2- Brookite
Anatase: I41/amd
semiconductor, photocatalyst, antimicrobial coating, oxygen sensor
The primary use of XRD is phase identification– what is in your sample? is it what you were trying to make?
90% of all analysis done in our lab is phase ID.
The diffraction pattern for every phase is as unique as your fingerprint.
Phases with the same chemical composition can have drastically different diffraction patterns, see the example of TiO2.
The phase composition can be identified and quantified.
We have a reference database, the PDF, that contains 250,000+ diffraction patterns from 135,000+ unique materials
Brookite: Pcab
no known use

3. Other Things to Do with XRD Data
Measure Unit Cell Lattice Parameters
Estimate Crystallite Size and Microstrain
Measure Residual Stress (macrostrain)
Measure Texture or Epitaxy
Evaluate Thin Film Quality
Determine Crystal Orientation
Determine Crystal Structure
Measuring lattice parameters is useful, because lattice parameters can vary as a function of, and therefore give you information about, doping, solid solutions, alloying, strains, etc.
estimate crystallite size of nanocrystals; may also be able to analyze shape
measure microstrain, lattice distortions, stacking faults, and other defects; how perfect or imperfect are the crystallites in your sample
residual stress: measure the strain in a machined part, such as a brake rotor or film on substrate
measure texture or epitaxy: important for the strength of soda cans to the performance of semiconductors
solve a crystal structure- figure out how the atoms are arranged, and then try to understand how that affects the properties. XRD has been used to solve the structure of fast-ion conductors for fuel cells or of proteins and viruses, such as HIV. In all cases, the crystal structure affects how the material performs.

4. Diffraction Techniques Available at the CMSE
X-Ray Powder Diffraction (XRPD)
Grazing Incidence Angle Diffraction (GIXD)
Pole Figure Mapping
Microdiffraction (mXRD)
Residual Stress Mapping
In situ XRD
Reciprocal Space Mapping
Single Crystal Diffraction (SCD)
Back-Reflection Laue
X-Ray Reflectivity (XRR)
Small Angle X-Ray Scattering (SAXS)
XRPD for all polycrystalline samples- not just for powder. Can include powders, sintered pellets, coatings on substrates, finished machined pieces
GIXD for thin film phase analysis

5. Rigaku Powder Diffractometer
The high-power generator provides X-rays to two horizontal-circle diffractometers.
The diffractometer on one side is optimized for high intensity and fast data collection; the diffractometer on the other side is optimize for high resolution and accuracy.
Both diffractometers have diffracted beam optics to give us a very low, linear background (esp. compared to larger PSD and area detectors). This is useful for analyze subtle details in the XRD pattern or for studying amorphous content.
Sample size: 20mm x 10mm x 0.3mm
a bit limited in the types of samples that it can accommodate; we do have some flexibility with different sample holders and mounting procedures
Fast, precision XRPD
High-power rotating anode source

6. Bruker D8 with GADDS
The key feature of this diffractometer is a 2D detector that collects a lot of data simultaneously.
This detector is huge compared to that on the Rigaku- roughly equivalent to ½ million point detectors in an array
Fast data collection (at the expense of resolution and background noise)
Ideal for:
pole figures
microdiffraction
large grain size samples
Eularian cradle facilitates a large range of tilts and rotations. The Eularian Cradle can accomodate 6” wafers, powders in top-loaded sample holders or in capillaries, dense pieces up to 60mm x 50mm x 15mm (and maybe even larger).
In situ XRD: furnace for heating a sample up to 900°C
Large 2D detector for simultaneous collection of diffraction data over a 2theta and chi (tilt) ranges as large as 30°

7. mXRD with the D8
The X-ray beam is collimated down to a spot with a diameter of 0.5mm to 50 microns. We could even buy a 10 micron collimator is somebody needed it.
Combined with a motorized xyz stage, we can collect diffraction patterns from several select spots on a sample; we can even map across a samples entire surface.
We see on the graph above the diffraction pattern for a polycrystalline region with small grain size; a region with textured polycrystalline; and a region with both fine and coarse grains.
The classic example that Bruker loves to show is them mapping the data at different points along a spring.
This also permits combinatorial screening.

8. PANalytical X’Pert Pro MPD
This diffractometer is all about flexibility.
This diffractometer can be used to collect XRPD, GIXD, XRR, residual stress, and texture data.
Prefix optics allow the configuration to be changed in a matter of minutes (rather than hours with another instrument).
Change the diffractometer to suit your experiment; don’t change your experiment to suit the diffractometer
A vertical-circle theta-theta goniometer is used so that the sample always lies flat and does not move.
Sample sizes may be as large as 60mm diameter by 3-12mm thick, though a more typical sample size is 10-20mm diameter.
Prefix optics allow the configuration to be quickly changed to accommodate a wide variety of data collection strategies.

9. Mix `n` Match Incident-Side Göbel Mirror
Computer-Controlled Divergence Slit
Sample Stage
15-position automated sample changer
Eularian Cradle
High-temperature furnace
Cryostat
Receiving-Side
Coarse parallel beam collimator w/ point detector
Fine parallel beam collimator w/ point detector
High-speed detector (w/ or w/o monochromator)
Sample Stages include:
15 specimen automatic sample changer
open Eulerian cradle with z-translation as well as phi and psi rotation for texture, reflectivity, and residual stress measurements
High temperature furnace C in air, vacuum or inert
Kryostat- to 12 K
Data collection modes can be changed between:
high-speed high-resolution divergent beam diffraction
Programmable divergence slits can maintain a constant irradiated area on sample surface
parallel beam diffraction using incident Gobel mirror and receiving-side parallel plate collimator
eliminates errors due to irregular sample surfaces, sample displacement, and defocusing during glancing angle measurements

10. Reconfigurable in Minutes
High-speed in situ XRD
Use high speed optics to observe changes in sodium alanate as it releases its stored hydrogen with time during an isothermal temperature hold; 5 min per data set, over 100 data sets per measurement
determine that the reaction rate constants at 150 C are 3.8x10-4 /s and 9.4x10-6 /s
This instrument has been used to collect thousands of diffraction patterns per experiment; combine with automated data analysis
Use Parallel beam optics for high accuracy measurement of peak positions: determine that there is a 337 MPa compressive stress with a slight shear component
parallel beam optics also very useful for dealing with samples with irregular surfaces
High-accuracy parallel-beam XRD

11. Bede D3 Triple Axis Diffractometer
High resolution measurements with extensive beam conditioning optics for thin film analysis
An extremely high resolution instrument with beam-conditioning optics that remove Ka2, divergent X-rays, etc.
For thin film analysis, particularly of semiconductor multilayers:
GIXD
analysis of rocking curves,
lattice mismatch, and
reciprocal space maps
Could also be used for high precision XRR
This instrument is typically used to measure the perfection or imperfection of the crystal lattice in thin films (i.e. rocking curves), the misalignment between film and substrate in epitaxial films, and reciprocal space mapping.
XRR
Rocking Curve

12. Bruker SMART APEX
A 2D CCD detector for fast, high precision transmission diffraction through small single crystals.
Another instrument featuring a high-speed 2D area detector. This one uses a CCD detector– it is smaller than the GADDS, but higher resolution and able to handle more intense diffraction peaks.
Designed primarily to determine the crystal structure of single crystals; mostly organic macromolecules
can also be used for determining crystal orientation
A cryostat is available to cool samples down to 100 K in air, which permits more precise determination of atom positions in large organic crystals.
For single crystal analysis, we also have a back-reflection Laue to determine crystal orientation (polaroid film or 2D multiwire detector)
Determine the orientation of large single crystals and thin film single crystal substrates

13. SAXS
The beam path length of 60.4 cm allows the resolution of crystallographic and structural features on a length scale from 1.8nm to 40nm (1.8nm is near the maximum resolvable length scale for XRPD in our other systems).
high-power rotating anode X-ray source
two-dimensional detector for real-time data collection
Hasn’t worked in over 1 year.
For analysis of polymers and thin nanostructured materials.
We can actually get microstructural, as well as crystallographic, information
A long X-ray beam path allows this instrument to measure X-rays that are only slightly scattered away from the incident beam. The two-dimensional detector allows entire Debye rings to be collected and observed in real time. A heater is available to heat the sample up to 200°C.

14. Upcoming Sessions
Jan pm- Nanocrystallite Size Analysis using XRD
Jan pm- The Wonders of X-Ray Diffraction
Training for New Users
XRD Lab Orientation & Safety: Jan 31, 1:30 to 3 pm
Instruction for Novice Users: Jan 31, 3 to 5 pm
Instruction for Experienced Users: Feb 2, 2 to 4 pm