X-ray Diffraction
Featured Equipment
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The X-Ray Diffraction SEF contains a suite of 6 diffractometers for analysis of polycrystalline, single crystal, thin film, polymer, and nanostructured samples.
*For more information about the X-Ray facility, please click here*
Personnel
Dr. Scott A Speakman, Research Specialist
Office: 13-4009A
Phone: (617)253-6887
Fax: (617)258-6478
E-mail: speakman@mit.edu
Location:
Instrument Lab- Building 13, room 4027 (4th floor)
Computer Lab- Building 13, room 4041 (4th floor)
Instruments available:
Rigaku Rotating Anode X-Ray Powder Diffractometers
Fast X-ray Powder Diffraction (XRPD) is facilitated by a high-power rotating anode generator that supplies a high flux of X-rays to two different horizontal-circle powder diffractometers: a 185mm Bragg-Brentano diffractometer is optimized for high intensity for fast data collection; a 250mm Bragg-Brentano diffractometer is optimized for high resolution and accuracy at slower data collection speeds. Sample size is generally 20mm x 10mm x 0.3mm, though we have a variety of sample holders and mounting procedures to accommodate varied sample geometries.
Bruker D8 Discover with Vantec-2000 Detector
A robust two-dimensional area detector facilitates high-speed data collection; a range as large as 30° 2theta and 30° chi can be measured simultaneously. Combined with an Eularian cradle, this instrument is ideal for texture and stress measurements; as well as XRPD from large-grain sized materials, single crystal orientation analysis, and grazing-incidence small angle X-ray scattering (GISAXS). A collimator conditions the X-ray beam to a spot with a diameter from 1mm to 0.05mm; combined with the motorized x-y-z stage this permits microdiffraction and sample surface mapping.
Samples can include powders, dense pieces up to 6” in diameter, and thin films.
PANalytical X’Pert Pro Multipurpose Diffractometer
This diffractometer features two interchangeable sets of optics: a Bragg-Brentano geometry utilizing programmable divergence slits and a high-resolution linear position sensitive detector for high-speed data collection; and a parallel beam geometry using a Gobel mirror and parallel plate collimator. These optics are highly configurable, allowing the instrument to be optimized for XRPD, thin film analysis, graxing incident angle diffraction (GIXD), residual stress analysis, and texture analysis.
Interchangeable sample stages include a 15 sample automated changer, an Open Eularian cradle, a furnace with a maximum temperature of 1200°C, and a cryostat with a minimum temperature of 11 K. Sample sizes may be as large as 60mm diameter by 3-12mm thick, though a more typical sample size is 10-20mm diameter.
Bruker D8 Discover High-Resolution X-Ray Diffractometer
This instrument is optimized for the analysis of epitaxial thin films using high-resolution X-ray diffraction (HRXRD) and analysis of thin films using X-ray reflectivity (XRR). Incident optics can be changed between a Gobel mirror, a Ge(022) 4-bounce monochromator, and a Ge(044) 4-bounce monochromator. Diffracted-beam optics can be changed between a programmable receiving slit for 2 axis HRXRD and XRR; a Ge(022) 3-bounce analyzer crystal for 3-axis HRXRD, and a linear position sensitive detector for high-speed reciprocal space mapping (RSM). These options allow the instrument to be matched to the film of interest for optimized data collection. The instrument can accommodate up to an 8” wafer, or samples as small as 1mm x 1mm.
Bruker Single Crystal Diffractometer
This diffractometer has been transferred to the MIT Dept. of Chemistry. Please contact Peter Muller (x-ray-www@mit.edu) if you are interested in using it. This diffractometer uses a two-dimensional CCD detector for fast, high precision transmission diffraction through small single crystals. Designed primarily to determine the crystal structure of single crystals, this diffractometer 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.
Back Reflection Laue Diffractometer
This system uses a two-dimensional multiwire detector to collect back-reflection Laue patterns to determine the orientation of large single crystals and thin film single crystal substrates. This instrument is currently out of order, with no immediate plans for repairs. This instrument can be brought back on-line if there is sufficient interest. Crystal orientation can be done using the Bruker D8 with Vantec-2000 detector instead.
Bruker Small Angle X-Ray Scattering (SAXS)
Used for SAXS, this instrument combines a high-power rotating anode with a two-dimensional detector and a long X-ray beam path 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. The current 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). A heater is available to heat the sample up to 200°C. This system is currently out of order; we hope to have it available again by fall of 2009.
Data Analysis Software
A variety of commercial and public domain software is available for data analysis. Most XRPD, SAXS, HRXRD, and XRR data analysis techniques can be easily performed using these available software.
The X-ray Data Analysis Lab has computers equipped with the ICDD Powder Diffraction File (PDF) database for inorganic materials and the Cambridge Structure Database (CSD) for organic materials.
The most commonly used software packages in the lab are:
- MDI Jade for XRPD analysis
- PANalytical X’Pert HighScore Plus for XRPD analysis
- Bruker Leptos for HRXRD and XRR analysis
- Bruker Multex Area 2 for texture analysis
- PANalytical X’Pert Stress for residual stress analysis
- PANalytical X’Pert Reflectivity for XRR analysis
- GSAS for Rietveld refinement
- PowderCell for XRPD simulation
