Accuracy in powder diffraction II

248 Pages·1992·14.5 MB·English

by  Prince, E.

PUBUCAT10NS'"'i
A11103 Tlllfl?
I
United States Department of Commerce
Technology Administration
National Institute of Standards and Technology
NIST Special Publication 846
Accuracy in Powder Diffraction II
Proceedings of the International Conference
May
26-29, 1992
7
he National Institute of Standards and Technology was established in 1988 by Congress to "assist
industry in the development of technology needed to improve product quality, to modernize
. . .
manufacturing processes, to ensure product reliability and to facilitate rapid commercialization ... of
. . .
products based on new scientific discoveries."
NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S.
industry's competitiveness; advance science and engineering; and improve public health, safety, and the
environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national
standards of measurement, and provide the means and methods for comparing standards used in science,
engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized
by the Federal Government.
As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic
and applied research in the physical sciences and engineering and performs related services. The Institute
does generic and precompetitive work on new and advanced technologies. NIST's research facilities are
MD CO
located at Gaithersburg, 20899, and at Boulder, 80303. Major technical operating units and their
principal activities are listed below. For more information contact the Public Inquiries Desk, 301-975-3058.
Technology Services Manufacturing Engineering Laboratory
• Manufacturing Technology Centers Program • Precision Engineering
• Standards Services • Automated Production Technology
• Technology Commercialization • Robot Systems
• Measurement Services • Factory Automation
• Technology Evaluation and Assessment • Fabrication Technology
• Information Services
Materials Science and Engineering
Electronics and Electrical Engineering Laboratory
Laboratory • Intelligent Processing of Materials
• Microelectronics • Ceramics
• Law Enforcement Standards • Materials Reliability'
• Electricity • Polymers
• Semiconductor Electronics • Metallurgy
• Electromagnetic Fields' • Reactor Radiation
• Electromagnetic Technology'
Building and Fire Research Laboratory
Chemical Science and Technology • Structures
Laboratory • Building Materials
• Biotechnology • Building Environment
• Chemical Engineering' • Fire Science and Engineering
• Chemical Kinetics and Thermodynamics • Fire Measurement and Research
• Inorganic Analytical Research
• Organic Analytical Research Computer Systems Laboratory
• Process Measurements • Information Systems Engineering
• Surface and Microanalysis Science • Systems and Software Technology
• Thermophysics^ • Computer Security
• Systems and Network Architecture
Physics Laboratory • Advanced Systems
• Electron and Optical Physics
• Atomic Physics Computing and Applied Mathematics
• Molecular Physics Laboratory
• Radiometric Physics • Applied and Computational Mathematics^
• Quantum Metrology • Statistical Engineering^
• Ionizing Radiation • Scientific Computing Environments^
• Time and Frequency' • Computer Services^
• Quantum Physics' • Computer Systems and Communications^
• Information Systems
'At Boulder, CO 80303.
^Some elements at Boulder, CO 80303.
760
i^^z
1
NIST Special Publication 846
Accuracy in Powder Diffraction II
Proceedings of the International Conference
May
26-29, 1992
E. Prince and J. K. Stalick, Editors
Materials Science and Engineering Laboratory
National Institute of Standards and Technology
MD
Gaithersburg, 20899
Organized by:
Commission on Powder Diffraction of the
International Union of Crystallography
Sponsored by:
JCPDS—International Centre for Diffraction Data
International Union ofCrystallography
National Institute of Standards and Technology
Issued October 1992
5
e.
U.S. Department of Commerce
Barbara Hackman Franklin, Secretary
Technology Administration
Robert M. White, Under Secretary for Technology
National Institute of Standards and Technology
John W. Lyons, Director
National Institute of Standards U.S. Government Printing Office For sale by the Superintendent
and Technology Washington: 1992 of Documents
Special Publication 846 U.S. Government Printing Office
DC
Natl. Inst. Stand. Technol. Washington, 20402
Spec. Publ. 846
241 pages (Oct. 1992)
CODEN: NSPUE2
Foreword
Few areas ofresearch endeavour in the physical sciences have experienced a renaissance on such a scale,
and few have had such an impact on related disciplines during the past 15 years, as has powder diffraction.
Sensing this imminent revolution back in 1979, the U. S. National Bureau ofStandards (now NIST) hosted a
conference entitled Accuracy in Powder Diffraction. The proceedings of this symposium were subsequently
published as NBS Special Publication 567 and this document is still widely quoted in the literature, more
than 10 years later!
In the years since this benchmark meeting, new generations of high resolution and intense sources of
X-rays and neutrons have been designed and built, new and exciting methods for data collection and analysis
have been developed, and powerful computers have come within reach of, if not on, scientists' desks. Never
before have so many previously neglected materials come under such close scrutiny, and never before has
it been possible to study these materials under such a wide range of non-ambient conditions. Diffraction
patterns previously collected only for phase identification or unit cell determination are now used to study
such things as the subtleties of electron density distribution, the mechanisms of phase transformations, and
the distribution of cation ionization states.
In the light of this renaissance, the lUCr Commission on Powder Diffraction (CPD), in conjunction with
the National Institute of Standards and Technology, JCPDS-International Centre for Diffraction Data, and
the International Union of Crystallography, organized a second conference, Accuracy in Powder Diffraction
II, as a continuation of the series started in 1979. Six sessions provided the framework for APD-II: phase
identification and quantification; accuracy and standards; new developments in software and data analysis;
profile fitting, decomposition, and microstructural effects; novel applications and structural science; new
developments in hardware, including detectors, and studies under non-ambient and time-resolved conditions.
The scientific sessions incorporated keynote, invited, oral and poster papers, a tribute to the late W.
Parrish, and two workshops organized by the JCPDS-ICDD, entitled ICDD round robin on powder diffrac-
tomeier sensitivity and Indexing methods. In addition, the program for the last session of the meeting was
specifically designed to interface smoothly with the Workshop on X-ray and Neutron Diffraction at High
Pressure, organized by the High pressure Group of the lUCr, which was held in Washington, DC, at the
Geophysical Laboratory of the Carnegie Institution of Washington. Many attendees obtained substantial
benefit from attending both of these meetings.
Generous support for the attendance of young scientists and invited speakers was obtained from the
lUCr and the JCPDS-ICDD, respectively. It need hardly be added that the continued financial support of
both of these organizations is extremely valuable to, and very much appreciated by the powder diffraction
community in general and the APD-II Organizing Committee in particular. The cooperation and generosity
ofthe NIST in providing support in the form ofboth personnel and facilities was essential for the organization
of the meeting, and for this we are also very grateful.
I take the opportunity here to express my thanks to the members of the Scientific Program Committee
for their hard work and cooperation; their efforts resulted in an enlightening and fruitful meeting.
R.J. Hill
Chairman, Scientific Program Committee
Acknowledgments
The timely publication ofthis volumeofproceedings was made possible by the cooperation ofthe authors,
who provided machine-readable text, many of them in I^TgX or Wordperfect, so that the labor involved in
producing camera-ready copy was minimal. We are grateful to Carol O'Connor for invaluable assistance
in preparing the text for the printer. The success of the conference was assured by the efforts of the
international program committee, ably chaired by Rod Hill, and for the smooth running of the conference
we are indebted to Kathleen Kilmer and her staff in the NIST conference office, particularly Tammie Grice
and Lori Phillips. The conference would not have occurred at all without the impetus of Ray Young and
the lUCr Commission on Powder Diffraction and the generous sponsorship of the International Union of
Crystallography and the JCPDS-International Centre for Diffraction Data.
E. Prince
J. K. Stalick, Editors
111
Commission on Powder Diffraction Local Committee
R. A. Young (USA), Chairman E. Prince, Co-chairman
Z. Bojarski (Poland) J. K. Stalick, Co-chairman
D. E. Cox (USA) T. Grice
J. Fiala (Czechoslovakia) K. Kilmer
A. W. Hewat (France) C. O'Connor
R. J. Hill (Australia) L. Phillips
J. I. Langford (UK) J. E. Post
D. Louer (France) C. T. Prewitt
P.-E. Werner (Sweden)
T. Yamanaka (Japan)
D. K. Smith (USA), Consultant
L. Frevel (USA), JCPDS-ICDD representative
International Program Committee Special thanks to:
R. J. Hill (Australia), Chairman Blake Industries, Inc.
D. E. Cox (USA) Charles Supper Company
J. Fiala (Czechoslovakia) Fein-Marquart Associates, Inc.
H. Fuess (Germany) Materials Data Inc.
D. Louer (France) Molecular Simulations, Inc.
R. J. Nelmes (UK) Philips Electronic Instruments Company
E. Prince (USA) Polycrystal Book Service
D. K. Smith (USA) Scintag, Inc.
H. Toraya (Japan) Siemens Analytical X-ray Instruments
L. Zevin (Israel)
IV
Table of Contents
T. C. Huang. Contributions of William Parrish to Powder Diffraction 1
B. L. Davis. Quantitative Phase Analysis with Reference Intensity Ratios 7
L. Zevin. Standardless Method of Quantitative X-ray Diffractometry 17
R. L. Snyder. Reference Intensity Ratios, Whole Pattern Fitting and Standardless X-ray Quanti-
tative Analysis 25
J. K. Stalick. Quantitative Phase Analysis with the Rietveld Method 34
H. Hermann and M. Ermrich. Microabsorption Corrections 38
,
M. Nakhmanson. Computer-Aided Phase Identification 47
P.-E. Werner. On the Relative Merits of Cameras and Diffractometers for XRD 51
J.-F. Berar. Data Optimization and Propagation of Errors in Powder Diffraction 63
J. P. Cline. NIST XRD Standard Reference Materials: Their Characterization and Uses 68
L. B. McCusker. Integrated Software for Structure Solution from Powder Data 75
J. M. Newsam, M. W. Deem and C. M. Freeman. Direct Space Methods ofStructure Solution
from Powder Diffraction Data 80
D. LOUER. Automatic Indexing Procedures and Applications 92
B. H. Toby and T. Egami. Accuracy in Pair Distribution Function Analysis for Crystalline and
Non-Crystalline Materials 105
J. I. Langford. The Use of the Voigt Function in Determining Microstructural Properties from
Diffraction Data by Means of Pattern Decomposition 110
V. Valvoda. Preferred Orientation Effects ." 127
T. M. HoLDEN and J. H. Root. Residual Stress Measurements with Neutrons 136
A. Le Bail. Modelling Anisotropic Crystallite Size/Microstrain in Rietveld Analysis 142
D. L. Bish. Structure Building with Rietveld Analysis 154
H. BoYSEN. Anharmonic Thermal Parameters, Disorder and Phase Transitions 165
J. P. Attfield. Recent Advances in the Use ofAnomalous Dispersion Effects 175
L. W. Finger. Instrumentation for Studies at the Powder/Single-crystal Boundary 183
M. Sutton, S. Brauer, Y. S. Yang, H. E. Fischer, J. O. Strom-Olsen and G. B.
Stephenson. Time-resolved X-ray Diffraction Studies of Crystallization in Metallic Glcisses 189
. .
V
R. J. Nelmes, J. S. LovEDAY AND J. M. Besson. New Developments in High-Pressure Neutron
Powder Diffraction 195
T. Yamanaka. Crystal Structure Analysis by Fitting of Powder Diffraction Data on Energy Dis-
persion 199
Abstracts. Session 1: Phase Identification and Quantification 206
Abstracts. Session 2: Accuracy and Standards 209
Abstracts. Session 3: New Developments in Software and Data Analysis 211
Abstracts. Session 4: Profile Fitting, Decomposition and Microstructural Effects 215
Abstracts. Session 5: Novel Applications and Structural Science 219
Abstracts. Session 6: New Developments in Hardware, Including Detectors, and Studies under
Non-ambient and Time-resolved Conditions 222
Author index 226
List ofparticipants 228
Disclaimer
Certain trade names and company products are identified in order to adequately specify the experimental
procedure. In no case does such identification imply recommendation or endorsement by the National
Institute ofStandards and Technology, nor does it imply that the products are necessarily the best available
for the purpose.
Abstract
The proceedings ofthe international conference Accuracy in Powder Diffraction II present the invited papers
and abstracts of the papers contributed to the conference, which was held at NIST, Gaithersburg, Mary-
land, during May 26-29, 1992. The conference was organized by the Commission on Powder Diffraction
of the International Union of Crystallography, and was jointly sponsored by NIST, JCPDS - International
Centre for Diffraction Data and the International Union of Crystallography. The proceedings contain 25
invited papers and 73 contributed abstracts. The program of the conference was divided into six topics:
Phase Identification and Quantification; Accuracy and Standards; New Developments in Software and Data
Analysis; Profile Fitting, Decomposition and Microstructural Effects; Novel Applications and Structrual
Science; and New Developments in Hardware, Including Detectors, and Studies under Non-ambient and
Time-resolved Conditions. A ceremonial session was devoted to a tribute to the late William Parrish and
his contributions to powder diffraction. In addition, there were two tutorial workshops organized by the
JCPDS - International Centre for Diffraction Data, one on diffractometer sensitivity and one on automatic
indexing methods.
Keywords: Accuracy; Instrumentation; Microstructure; Phase analysis; Powder diffraction; Software; Stan-
dards; Structural science.
vi
National Institute of Standards and Technology Special Publication 846. Proceedings of the international
conference Accuracy in Powder Diffraction II, held at NIST, Gaithersburg, MD, May 26-29, 1992. (Issued
October 1992)
Contributions of William Parrish to Powder Diffraction
T. C. Huang
IBM Research Division, Almaden Research Center
650 Harry Road, San Jose, CA 95120-6099, U.S.A.
Abstract
This paper summarizes some of the important con-
tributions of the late Dr. William Parrish to pow-
der diffraction. He was responsible for developing
many of the instruments and methods that became
commercial products widely used for powder diffrac-
tion analysis. His most important achievement was
the 1947 invention of the "Norelco" diffractometer
using a new X-ray optics geometry that gave high
intensity and resolution with good profile shape. It
is the basic instrument on which most powder work
has been done for almost half a century, and more
than 10,000 powder diffractometers are now in use
throughout the world. Afterjoining IBM in 1970, he
developed diffractometer automation methods that
eventually evolved into a series of IBM X-ray prod- Figure 1: The first "Norelco" powder diffractometer
ucts. A large number ofanalytical programs were de- invented by W. Parrish at Philips Laboratories, 1947.
veloped that added new capabilities to X-ray analy-
sis. In the early 1980s he began a systematic study of
synchrotron powder diffraction, and this synchrotron 1947 (figure 1). The instrument used a "new" X-
research provides the basis for a new and exciting era ray optics geometry to greatly increase the quality of
ofpowder diffraction. Many important advances will
powder diffraction patterns over those of an earlier
be possible based on his pioneering efforts. Parrish
diffractometer assembled by H. Friedman in 1945.
was not only a great powder diffractionist, but also The latter device used the spot focus with an effec-
a wonderful person, who will be greatly missed. tive size of 0.24 by 2.5 mm; the dimension ofthe line
Introduction focus in Parrish's device wais only 0.06 by 10 mm.
To improve asymmetricprofile broadening due to the
Ever since its discovery by Debye and Scherrer more large axial divergence in the Friedman diffractome-
than 75 years ago, the powder diffraction method has ter, Parrish used a set oflong parallel equally-spaced
played a significant role in the development of mod- thin Mo foils (Soller slits) in the incident beam. The
ern science and technology. The name ofBill Parrish long X-ray line source thus became effectively a num-
is linked closely to many ofthe most important steps ber of short overlapping narrow sources parallel to
in the evolution of powder diffraction instrumenta- the specimen axis ofrotation and had the additional
tion, from relatively primitivepowder cameras to the advantages of high intensity and high resolution. A
highly sophisticated and automated diffractometers second set ofparallel slits was placed in the diffracted
we now use. beam, and the large increase in resolution decreased
the profile widths of the peaks from about 0.35* to
Invention of the powder diffractometer 0.10°(2^). Figure 2 shows the optics and line profiles
of the two instruments.
Parrish's most important achievement involved the It is unfortunate that the Parrish diffractometer
invention of the "Norelco" powder diffractometer in
1
2 Contributions ofWilliam Parish to Powder Diffraction
pulse amplitudeswere proportional to the energies of
the X-ray quanta. This made possible the use of a
pulse height analyzer to accept only pulses ofampli-
tude within preselected limits and thereby greatly re-
duced the background with only afew percent loss of
characteristic line intensity. The combined action of
the Ni filter and electronic discrimination increased
peak-to-background ratio well beyond the range of
the Geiger counter used in early models. Figure 3
shows the effects of pulse height discrimination with
a scintillation counter on the spectrum ofa Cu X-ray
tube.
LWFILTCRED
a^^g^ma^ 11om(410.0001
'norm
MOO lOMOSUOO Icutanszooa
Figure 2: X-ray optics of the early and new diffrac- WITH
tometers (top) and their profiles: Si (422) and Cu FH) ,'
Ka. (bottom).
is often incorrectly referred as a Bragg-Brentano de-
vice. The counter tube diffractometer geometry was
uniquely Parrish's, and he was awarded a U.S. Patent
Figure 3: Spectrum of Cu X-ray tube recorded with
in 1951. More than 10,000 are now in use through-
a scintillation counter.
out the world; this alone could be recognized as a
most important achievement because it became the Parrish and his co-workers at Philips developed
basic instrument on which most powder work has
principles and mechanical devices to aid in simplify-
been done for almost halfof a century.
ing the alignment and calibration ofthe diffractome-
Within a few years, the new instrument had revo- ter (Parrish & Lowitzsch, 1959). A flat specimen
lutionized powder diffraction techniques and made
spinner for rotating the specimen in its own plane
possible major improvements in the measurement
was introduced to reduce the effect ofcrystallite size
of powder patterns. Following those developments,
statistics and in-plane preferred orientation on abso-
Parrish devoted himself to many years of intensive
lute and relative intensities (de Wolff, Taylor k, Par-
research aimed at improving both the instrumenta-
rish, 1959). He was one ofthe first to investigate the
tion of the diffractometer and the understanding of
sources ofsystematic errors in counter diffractometry
the basic principles of the new instrument. He was
(Parrish &; Wilson, 1959) and the use ofthe centroid
a pioneer in the utilization of scintillation and pro-
method for handling aberrations in precision lattice
portional counters with pulse amplitude discrimina- parameter determination (Taylor, Mack & Parrish,
tion, making possible large improvements in X-ray
1964).
detection (Parrish and Kohler, 1956). Both detec-
Parrish also extended the applications of the
tors had dead times ofthe order of0.25 //sec, and the diffractometer and made modifications of the stan-