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Our Laboratory Facilities
Introduction
The X-ray diffraction laboratory includes a Scintag Pad V diffractometer /
goniometer with Scintillation detector, Datascan software (Materials Data, Inc.)
for diffractometer automation and data collection, and Jade Software (Version
9.1, also from MDI) accessing the complete IDCC Powder diffraction
file (PDF-4) database for data analysis and interpretation.
The laboratory is open to all University personnel who are interested in obtaining
power-diffraction data for their samples. The laboratory can be used for powder
samples (rock, clay minerals, experimental materials) and (to some extent) thin
film samples. User requirements for lab use are on another
page. We do not have the capability to do single-crystal work in our laboratory.
The X-Ray Diffraction Laboatory. Scintag PadV Gonniometer/Diffractometer on
left, computer used for diffractometer operations and data collection near the
center, and computer used for data analysis and data printing on right. Photo
taken in 2004. Lab now has newer computers and printer than those shown here.
Before use of the laboratory is permitted, all users must demonstrate
familiarity with basic radiation safety procedures, be trained in the use of
the equipment, and make arrangements to pay for their use of the laboratory.
Please read Requirements for Users of the X-ray Diffraction
Laboratory for details of how to be certified for laboratory use.
Only qualified persons (faculty, staff, students) affiliated with the University
of New Mexico are permitted to use the laboratory. Laboratory personnel can
do work for outside users (i.e., other Universities, government agencies and
private corporations) on a contract basis; if you are in this group and are
interested in having XRD work done, please contact the Lab Manager, Jim Connolly,
by Email (connolly@unm.edu).
Credit for Use of Laboratory in Published Papers
We ask that all users of the laboratory give credit for their use of the laboratory
in published papers if they present or refer to data acquired in the lab. A
suggested wording for that credit (which also includes data collection and analysis
parameters usually required when publishing results) is given below. The wording
may be modified as necessary for different operating conditions used:
Powdered samples were analyzed by X-ray diffraction (XRD) in the XRD Laboratory
in the Department of Earth and Planetary Sciences at the University of New
Mexico, using a Scintag Pad V diffractometer with DataScan 4 software (from
MDI, Inc.) for system automation and data collection. Cu-K-alpha radiation
(40 kV, 35 mA) was used with a Bicron Scintillation detector (with a pyrolitic
graphite curved crystal monochromator). Data were analyzed with Jade Software
(from MDI, Inc.) using the ICDD (International Center for Diffraction Data)
PDF4 database (rev. 2010) for phase identification.
Please allow the lab manager to review the XRD citation in your
papers before they are submitted for publication to assure that XRD parameters
are described accurately.
XRD Resources Available in the Lab
Our Scintag Pad V system was originally purchased in 1984. For many years,
Scintag operated as a small, independent developer of XRD equipment with a reputation
for excellence in both technology and service. In the 1990s, they were purchased
several times, each time becoming part of a larger corporation and moving farther
from their roots. They are now part of ThermoARL (a multi-national corporate
giant) who makes one powder XRD unit in Switzerland (that almost nobody buys
because other manufacturers make better equipment). In 2004 they officially
announced that they would no longer support the PAD V system.
This system is still a workhorse and by upgrading peripherals (like operating
software, HV power supply, etc.), having our local electronics wiz Bob Macy
available, and keeping a good supply of spare electronic parts around, we hope
to keep it alive for many years to come.
The Scintag (Rich Seifert) goniometer shown in the 10 degree 2-theta sample
exchange position. XRD tube housing on left is fixed. In a coupled scan, the
sample holder (center) rotates at 1/2 the rate of the detector (right). The
detector is a Bicron scintillation counter with a detector-side graphite monochromator
located next to the detector (where the array appears to bend). Boxes on the
deck to the left of the tube housing hold a variety of collimating slits for
limiting the width of the incident and diffracted X-ray beam.
Our current system uses the original diffractometer (goniometer and detector
electronics) and housing, but everything else is different from what was delivered
in 1984. The current (as of Spring, 2010) incarnation of our Scintag Pad V Diffractometer
includes the following hardware and software:
Rich Seifert, Inc. (Manufacturer) large-circle (150-275 mm radius) goniometer,
vertically mounted with 0.8 degree to 160 degree 2-theta analytical range.
This goniometer was manufactured by Rich.
Seifert Co. in Germany in the early 1980s (since acquired by GE as Seifert Analytical X-ray) and has a significantly larger analytical
radius than powder machines made later by Scintag in North America. It has
been a very reliable goniometer for us since first delivered (with a lot of
other long-since abandoned items) in 1984.
Bicron (Brand) Scintillation counter
(now produced by Saint-Gobain Crystals of Paris) with curved-crystal graphite monochromator, EG&G Ortec preamp, NIM/BIN
and power supply with RS-232 data/command interface. This exceedingly reliable
hardware has also been with us since 1984.
Spellman DF3 Solid State high-voltage
(maximum 60 kV) power supply. This unit, acquired in the mid 1990s, is an
all solid state unit which replaced the original tube-based unit delivered
with the unit in 1984. A little bit larger than your average personal computer
(but much heavier), it replaced several hundred pounds of transformers (which
we have kept in the base of the unit to keep it stable). Though we had two
failures in the unit over its lifetime (one of unknown cause and one related
to a storm-related power failure), it is infinitely more reliable than the
unit it replaced.
Haskris chilled-water closed-loop
circulating cooling system for X-ray tube cooling. An extremely reliable unit
from a company which is extremely helpful and responsive.
DataScan 4 Software from Materials
Data Incorporated (MDI) is used on a Pentium IV (Windows XP Professional)
workstation for data collection. MDI makes software for data collection and
analysis which is designed to work with a wide variety of XRD units from different
manufacturers. In 1985 the PAD V unit was delivered with a Data General computer
system with an operating system called RDOS. A few years later, operations
were switched to a Digital Equpment Corporation (DEC) VMS-based system which
continued until DEC disappeared and we could no longer obtain licences for
the poorly-supported operating system. In 1997 we went with DataScan to move
all of our operations to the Windows platform. Since we had already been using
Jade for data analysis, we could now move to their format (a variety of the
standard XRD data interchange format or DIF) and eliminate the data translation
step. Since it communicates directly with the RS-232 interface on the Scintag
unit, as soon as we got our cabling and communications parameters set, we
were off and running.
Jade Software from Materials Data
Incorporated (MDI) has been used since the mid-1990s for data analysis.
Prior to this, we were using the VMS version of Scintag's analytical software
which was extremely cumbersome to use, did not exchange data formats with
other platforms, and had extremely limited display and output capabilities.
The previous lab manager wrote some software to translate the VMS Scintag
data into a format importable into Jade and we moved our data analysis capabilities
to Jade and our Windows-based network. We started with Jade 3.0 in 1995 and
upgraded to Jade 5.0 in 1998. We currently have Jade 9.1 running on two lab computer systems (Pentium IV both running
Windows XP Pro). One of those systems has Shadow, MDI's profile "legacy" refinement
and pattern processing software. User's data is stored and processed on our
local area network's file server, enabling data access from outside laboratory
and from other departments on campus.
Jade makes use of the digital PDF4 database from the International
Center for Diffraction Data (ICDD) as a base of standards for phase identification
and automated search-match functions. The database now includes about 300,000
XRD patterns and includes experimental (inorganic and organic) data and calculated
patterns ("perfect" patterns calculated from crystal structure data). We also have the Inorganic Crystal Structure Database (ICSD) from NIST installed and usable either in stand-alone mode or from patterns calculated from the data for use by Jade. Both the ICDD and ICSD databases have their own interfaces to the data that allow extraction of more data than is easily extracted in Jade, including crystal structure data for Rietveld refinements, and a variety of analytical subsets of the database for specialized purposes.
We are incrementally installing Free and Open-Source software to broaden
our data analysis capabilities on the two systems dedicated to data analysis.
Software currently available includes Bob Reynold's NEWMOD software (for clay
mineral structure modeling), Dennis Eberl's Rockjock (Pattern fitting Quant
program) and Mudmaster (particle size analysis program), GSAS (Generalized
Structural Analysis System) and FullProf (both Freeware Rietveld profile refinement
systems) along with a few data conversion utilities to facilitate exchange
of data between programs.
Exciting Lab Upgrade News (as of December, 2010)
We have been awarded a National Science Foundation (NSF) Major Research Instrumentation (MRI) grant to acquire a new XRD instrument to supplement our existing Scintag Pad V system. We are in the process of investigating exactly what instrument we will be acquiring but expect to be adding the following capabilities (and possibly some more not listed here) to our analytical X-ray diffraction "toolbox":
Greatly increased data acquisition rates for standard powder data facilitated by the use of an advanced technology 1D and 2D detector
Automated sample exchange and sample spinning to enhance data collection throughput and particle statistics, enabling collection of better quality data from very small amounts of powder
3D automated stage for programmed multi-spot analysis of sample areas or irregular samples
Interchangeable X-ray sources (Cu, Co, Mo, Cr) and orientations (point and line modes) to tailor analytical conditions to the needs of particular experiments
A variety of incident beam optics to produce parallel, line-focal and cono-focal incident beams (in addition to the standard divergent beam geometry) for different specimen geometries
A non-ambient sample chamber with elevated or reduced temperature capabilities and the ability to stream a variety of environmental gasses as required for different experiments
An advanced suite of data collection and analytical software to allow routine quantitative determinations of rock or engineered powder mixtures, structure profile refinements, texture and stress analysis, construction of "average" bulk diffraction patterns from multiple small-area data points, etc.
New sample preparation equipment to allow routine preparation of very evenly ground powders suitable for quantitative X-ray diffraction work
Investigation of the myriad options available with new beam focussing and detector technology has proven more complicated than we originally expected, but we still hope to have an instrument purchased and in place by April of 2011. We will be updating this section of the page as we proceed with the purchase of the new instrument.
Updated December 29, 2010. Please send comment about (and suggested additions
to) this page to connolly@unm.edu.
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