Materials Science X-Ray Analysis Laboratory
The Department of Mechanical Engineering supports and houses the X-Ray Analysis
Laboratory with two Philips x-ray diffractometers, a Materials Research Diffractometer and a
Multi-Purpose Diffractometer. The instrumentation was funded from National Science
Foundation, Division of Materials Research and the U of R with equipment help from Bausch
& Lomb. The facility is about 5 years old. The Materials Research Diffractometer, MRD, is
well suited for very high-resolution work especially for thin films and single crystal multilayer
diffraction analysis; the Multi-Purpose Diffractometer, MPD, is for powder or polycrystalline
diffraction analysis at room or non-ambient temperatures with controlled atmospheres. These
instruments have a wide range of applications: they perform qualitative and quantitative
analysis of powder diffraction data, high resolution rocking curves for electronic epitaxial
wafers, quantifying defects and perfection in high quality crystals, measuring thin film
thickness, layer densities and interface quality. In bulk and thin film materials, one can
determine stresses, textures and
grain sizes. This is made
possible by pre-aligned,
interchangeable x-ray optical
modules for pre and post
processing of the x-ray beam.
The user can select from a
variety of Prefix optics,
depending on requirements for
intensity, focusing and tolerance
for beam divergence. These
modules can be exchanged in a
matter of minutes, without the
need for complicated
dismantling, reassembly and
realignment. Generally, higher
intensity is accompanied with
increased beam divergence. For
example, an asymmetric crystal
module, using a Ge (220) 4
crystal monochromator selects
Cu K?1 radiation at a beam
divergence as low as 18 arcseconds
and an intensity of 5
million counts per second. The
line and spot foci have intensity
100 times higher, but at the
expense beam divergence and
dispersion. The new goniometer
has a resolution on ? and 2? of
0.0001°. The Eulerian cradle has
5 degrees of freedom for sample orientation and position. The x-ray software is extensive with
programs for performing comparison of the diffraction pattern with known patterns, Rietveld
phase analysis, crystal orientations, textures, residual stresses, particle size analysis, film
thickness, epitaxial layers, etc. The results obtained on complex structures are precise yet very
fast. The data can be exported to spread sheets and other graphical programs. The instruments
are housed in the refurbished x-ray room in Hopeman 111 on River Campus. Both
diffractometers are using the same software so they are operationally transparent. The MPD
and MRD units including the very high resolution modules and goniometer are used in
selected Mechanical Engineering and Materials Science courses. For further information
about the instruments and their capabilities, contact Professor Stephen Burns or Chris Pratt.
See above for the color pictures of the X-Ray Optics for Selected Applications in Materials.
Contacts: Professor Stephen J Burns, at (585) 275-4071, he can be reached in Hopeman 236
or by e-mail at burns@me.rochester.edu ; Chris Pratt, schedules operation and use, she can be
contacted at (585) 275-7807, she is in Hopeman 115 and her e-mail is Pratt@me.rochester.edu.
Below are descriptions of the two x-ray diffraction systems we use for analysis of crystalline
materials.
1. General Purpose X-ray Diffraction System for phase analysis of
polycrystalline micro or bulk samples with a high temperature, controlled
atmosphere sample stage, plus focusing and parallel beam optics.
2. Eulerian Cradle, High Resolution, Horizontal X-ray Diffraction System
with these capabilities:
o High-Resolution X-Ray Diffraction, HRXRD, double-crystal or 4-bounce
x-ray geometry for studying large-face single crystals and epitaxial thin
films, rocking curve analysis.
o Bragg geometry for studying stress and texture in polycrystalline solids;
crystallographic alignment of single crystals.
o Grazing-Incidence geometry for phase analysis of polycrystalline thin
films and x-ray reflection for film thickness.
o High resolution powder diffraction.
The following information briefly describes these x-ray diffraction systems and provides
an operational overview to facilitate user planning. Additional information is available
via the links shown at the end of this page.
System Configurations and Operational Overview
All work with the following systems and in the X-Ray Analysis Laboratory must be
performed in compliance with established practices and procedures. See x-ray safety
procedures below.
1. General Purpose X-ray Diffraction System: Philips MPD
The general purpose X-ray diffractometer is a Philips X Pert MPD system with a
vertical ?-2? goniometer (160 mm radius). The x-ray source is a long-fine-focus,
ceramic x-ray tube with Cu anode. Normal operating power is 40 kV, 30 mA (or
less than 1.8 kW). The system optics consist of fixed divergence, anti-scatter, and
receiving slits, incident and diffracted beam Soller slits, a curved graphite
diffracted beam monochromator, and a proportional counter detector in Bragg-
Brentano, parafocusing geometry. The principal application of this system is for
phase analysis of polycrystalline samples. The Bulk Multi-Purpose Sample Stage
supports typical powder mounts but primarily accommodates large monolithic
specimens of a wide variety of sizes and shapes. In addition, specialized microcapillary
sample tubes mounted on Supper goniometers with a rotatable sample
stage has been constructed. An environmental chamber is available for use with