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Applications of Pulsed Neutron Powder Diffraction to Actinide Elements

Published online by Cambridge University Press:  06 March 2019

A. C. Lawson
Affiliation:
Materials Science and Technology Division Los Alamos National Laboratory Los Alamos, New Mexico 87545
B. Cort
Affiliation:
Materials Science and Technology Division Los Alamos National Laboratory Los Alamos, New Mexico 87545
C. E. Olsen
Affiliation:
Materials Science and Technology Division Los Alamos National Laboratory Los Alamos, New Mexico 87545
J. W. Richardson
Affiliation:
Intense Pulsed Neutron Source Division Argonne National Laboratory Argonne, Illinois 60439
M. H. Mueller
Affiliation:
Intense Pulsed Neutron Source Division Argonne National Laboratory Argonne, Illinois 60439
G. H. Lander
Affiliation:
Intense Pulsed Neutron Source Division Argonne National Laboratory Argonne, Illinois 60439
J. A. Goldstone
Affiliation:
Los Alamos Neutron Scattering Center Los Alamos National Laboratory Los Alamos, New Mexico 87545
A. Williams
Affiliation:
Los Alamos Neutron Scattering Center Los Alamos National Laboratory Los Alamos, New Mexico 87545
G. H. Rwei
Affiliation:
Los Alamos Neutron Scattering Center Los Alamos National Laboratory Los Alamos, New Mexico 87545
R. B. Von Dreele
Affiliation:
Los Alamos Neutron Scattering Center Los Alamos National Laboratory Los Alamos, New Mexico 87545
J. Faber Jr.
Affiliation:
Materials Science and Technology Division Argonne National Laboratory Argonne, Illinois 60439
R. L. Hitterman
Affiliation:
Materials Science and Technology Division Argonne National Laboratory Argonne, Illinois 60439
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Extract

We have been using the technique of pulsed neutron powder diffraction to study several problems in the physics and chemistry of the actinide elements. In these elements one often encounters very complex structures resulting from polymorphic transformations presumably induced by the presence of 5f-electrons. For exampie, at least five distinct structures of plutonium metal are found between room temperature and its melting point of 640°C, and two of the structures are monoclinic! Single crystals are usually not available, and the high resolution which is intrinsic to the time-of-flight powder technique is a powerful tool in the solution of complex structural problems. The relatively low absorption coefficients for neutrons for at least some actinide isotopes is an advantage when surface oxidation is a problem (as in high-temperature experiments) and provides good particle statistics so that high-quality data are available for Rietveld refinement. The low absorption of neutrons by other materials such as vanadium and fused silica enables the use of these materials for the containment of samples in high- and low-temperature environments, and the fixed geometry of the time-of-flight technique simplifies the design of furnaces and cryostats.

Type
V. X-Ray and Neutron Diffraction Applications Including Superconductors
Copyright
Copyright © International Centre for Diffraction Data 1987

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References

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