The Physics of

Actinide Compounds

PHYSICS OF SOLIDS AND LIQUIDS

Editorial Board: Josef T. Devreese • University of Antwerp, Belgium Roger P. Evrard • University of Liege, Belgium Stig Lundqvist • Chalmers University of Technology, Sweden Gerald D. Mahan • Indiana University, Bloomington, Indiana Norman H. March • University of Oxford, England

SUPERIONIC CONDUCTORS Edited by Gerald D. Mahan and Walter L. Roth

HIGHLY CONDUCTING ONE-DIMENSIONAL SOLIDS Edited by Jozef T. Devreese, Roger P. Evrard, and Victor E. van Doren

ELECTRON SPECTROSCOPY OF CRYSTALS V. V. Nemoshkalenko and V. G. Aleshin

MANY -PARTICLE PHYSICS Gerald D. Mahan

THE PHYSICS OF ACTINIDE COMPOUNDS Paul Erdos and John M. Robinson

THEORY OF THE INHOMOGENEOUS ELECTRON GAS Edited by S. Lundqvist and N. H. March

A Continuation Order Plan is available for this series. A continuation order wiII bring delivery of each new volume immediately upon publication. Volumes are biIIed only upon actual shipment. For further information please contact the publisher.

The Physics of

Actinide Compounds

Paul ErdOs University of Lausanne Lausanne, Switzerland

and

John M. Robinson Indiana University-Purdue University at Fort Wayne Fort Wayne, Indiana

PLENUM PRESS • NEW YORK AND LONDON

Library of Congress Cataloging in Publication Data

Erdos, Paul, date -The physics of actinide compounds.

(Physics of solids and liquids) Bibliography: p. Includes index. 1. Actinide elements. I. Robinson, John M., date -

QD172.A3E73 1983 546'.4

. II. Title. III. Series.

83 c 2331 ISBN-13: 978-1-4613-3583-2

DOl: 10.1007/978-1-4613-3581-8

e-ISBN-13: 978-1-4613-3581-8

© 1983 Plenum Press, New York Sotfcover reprint ofthe hardcover lst edition 1983 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013

All rights reserved

No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

Preface

The authors' aim is to present a review of experimental and theoretical research that has been done to establish and to explain the physical properties of actinide compounds. The book is aimed at physicists and chemists. It was thought useful to collect a large selection of diagrams of experimental data scattered in the literature. Experiment and theory are presented separately, with cross­references.

Not all work has been included: rather, typical examples are discussed. We apologize to all researchers whose work has not been quoted. Since we report on an active field of research, clearly the data and their interpretation are subject to change.

We benefitted greatly from discussions with many of our colleagues, particularly with Drs. G. H. Lander and W. Suski. The help of Mrs. C. Bovey and Ch. Lewis in the preparation of the manuscript, and the artwork and photo­graphic work of Ms. Y. Magnenat and E. Spielmann of the Institute of Experi­mental Physics of the University of Lausanne, are gratefully acknowledged. Our particular thanks are due to Ms. J. Ubby for her skillful and patient editorial work.

We express our thanks to the Swiss National Science Foundation and the Herbette Foundation of the University of Lausanne, who promoted the cooperation of the authors.

Contents

list of Tables xi

CHAPTER 1. Introduction 1

CHAPTER 2. Survey of Experimental Data 7 2.1. Experimental Techniques ........................... 7

2.1.1. Sample Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 .2. Neutron Diffraction. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.3. Nuclear Magnetic Resonance. . . . . . . . . . . . . . . . . . . . . . 9 2.1.4. Mossbauer Resonance .......................... 9 2.1.5. Muon Spin Rotation (~SR) . . . . . . . . . . . . . . . . . . . . . .. 11 2.1.6. Other Experimental Techniques. . . . . . . . . . . . . . . . . . .. 12

2.2. NaCI-Type Metallic Actinide Compounds ..... .'. . . . . . . . . .. 13 2.2.1. General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 2.2.2. Uranium Monophosphide . . . . . . . . . . . . . . . . . . . . . . .. 16 2.2.3. Uranium Monoarsenide ......................... 22 2.2.4. Uranium Mononitride .......................... 26 2.2.5. Uranium Antimonide . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 2.2.6. Uranium Monochalcogenides . . . . . . . . . . . . . . . . . . . . .. 33 2.2.7. Neptunium Carbide . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36 2.2.8. Neptunium Monopnictides .... . . . . . . . . . . . . . . . . . . . 38 2.2.9. Plutonium Compounds. . . . . . . . . . . . . . . . . . . . . . . . .. 42 2.2.10. Solid Solutions of Uranium Monopnictides and Mono-

chalcogenides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44 2.3. UX2"Type and UXY-Type Tetragonal Uranium Compounds. . . .. 51 2.4. A3X4-Type Metallic Actinide Compounds. . . . . . . . . . . . . . . .. 58 2.5. Intermetallic Actinide Compounds ..................... 62

2.5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62 2.5 .2. AX2-Type Intermetallics . . . . . . . . . . . . . . . . . . . . . . . .. 63 2.5.3. AX3-Type Intermetallics . . . . . . . . . . . . . . . . . . . . . . . .. 69 2.5.4. Miscellaneous Intermetallics ...................... 72

vii

viii CONTENTS

2.6. Actinide Oxides ................................. , 74 2.6.1. Uranium Dioxide ............................. 76 2.6.2. U0 2-Th02 Solid Solutions ...................... , 79 2.6.3. Other Uranium Oxides ......................... , 81 2.604. Neptunium Dioxide ........................... , 83 2.6.5. Intermetallic Oxides ........................... 85

2.7. Actinide Halides ................................. 86 2.7.1. Uranium Triiodide ............................ , 86 2.7.2. Other Actinide Halides. . . . . . . . . . . . . . . . . . . . . . . . .. 90

2.8. Other Compounds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 91 29. Spectroscopic Data on Actinide Ions ................... , 92

CHAPTER 3. Survey of Theory 99 3.1. Localized Electron Theories ......................... , 99

3.1.1. Assumptions of the Crystal-Field Model .............. 99 3.1.2. Crystal-Field Theory . . . . . . . . . . . . . . . . . . . . . . . . . .. 103

3.1.2a. Mathematical Formulation .................... 105 3.1.2b. The Coulomb Hamiltonian .................... 106 3.1.2c. The Spin-Orbit Hamiltonian .................. , 108 3.1 .2d. The Crystal-Field Hamiltonian . . . . . . . . . . . . . . . . .. 111 3.1 .2e. Point Symmetry .......................... , 113 3.1 .2f. Matrix Elements of JC cf' ..................... , 115 3.1 .2g. The Zeeman Hamiltonian .. . . . . . . . . . . . . . . . . . .. 117 3.1.2h. Thermodynamic Averages. . . . . . . . . . . . . . . . . . . .. 117 3.1 .2i. Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 120 3.1 .2j. Comments on the Crystal-Field Theory . . . . . . . . . . .. 121

3.1.3. Interionic Interactions ......................... , 123 3.1.3a. Heisenberg Exchange . . . . . . . . . . . . . . . . . . . . . . .. 123 3.1 .3b. Anisotropic Exchange ....................... 124 3.1.3c. Electric Multipole Interactions ................. , 125 3.1.3d. Biquadratic Exchange. . . . . . . . . . . . . . . . . . . . . . .. 125 3.1.3e. RKKY Exchange .......................... , 125 3.1.3f. Coqblin-Schrieffer Exchange . . . . . . . . . . . . . . . . . .. 129

3.1.4. Theories of First-Order Transitions Based on Localized Models .................................... 133

3.1Aa. Biquadratic Exchange. . . . . . . . . . . . . . . . . . . . . . .. 133 3.1Ab. Allen's Theory of U0 2 •.••.•••.•.••••••.•••. , 135 3.1Ac. Theories of Np02 .......................... 142 3.1.4d. The Long-Wang Theory of UP .................. 144 3.1Ae. Blume's Level-Crossing Theory. . . . . . . . . . . . . . . . .. 146 3.1.4f. A Theory of UI3 . • . . . . • . . . • . . . . . . . . . . . . . . .. 147

3.2. Theories Involving Itinerant Electrons .................. , 148

CONTENTS ix

3.2.1. Band Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 149 3.2.1a. Introduction .............................. 149 3.2.1 b. Actinide Metals. . . . . . . . . . . . . . . . . . . . . . . . . . .. 150 3.2.1c. NaCI-Type Actinide Compounds ................ 152

3.2.2. Spin-Fluctuation Models. . . . . . . . . . . . . . . . . . . . . . . .. 155 3.2.3. Electron Delocalization Model. . . . . . . . . . . . . . . . . . . .. 157

3.3. A Theory Intermediate to the Localized and Band Models. . . . .. 164 3.4. Similarities between Mixed-Valence Rare Earths and Metallic

Actinide Compounds ........................ . . . . .. 169

APPENDIX A. Irreducible Tensor Operators ............ 171

APPENDIX B. Magnetic Structures. . . . . . . . . . . . . . . . . . . .. 175

References ........................................ 185

Author Index

Subject Index

199

207

List of Tables

1. The Three Groups of Magnetic Elements, and a List of the Actinide Elements Together with Their Electronic Configurations outside the [RnJ Core 2

2. The Major Classes of Actinide Compounds 3 3. Compounds of the Type AX, with the NaCl Structure 14 4. Tetragonal Conductor or Semiconductor Compounds of the Type

AX2 and AXY 52 5. A 3 X 4-Type Compounds of Body-Centered Cubic Structure 59 6. Intermetallic Actinide Compounds of the Type AX2 64 7. Intermetallic Actinide Compounds of the Type AX3 65 8. Selected Properties of Actinide Oxides 75 9. Listing of Actinide Halides 86

10. D2d Spectroscopic Parameters of If+ 93 11. Crystal-Field Parameters and Mean Radii of Actinides 95 12. Observed and Calculated Crystal-Field Splittings of the Ground State

of Np3+ in LaCh 96 13. Slater Integrals Fi and Spin-Orbit Coupling Parameter A for Trivalent

Actinides in LaC13 Host 97 14. Comparison of Experimental and Theoretical Values of the Slater

Integrals Fi and Spin-Orbit Coupling Constant for U3+ Ions in LaCh 97 15. Composition of the Eigenstates of the Lowest-Lying Manifold of

Crystal-Field States of the U3+ Ion, as Observed in LaCl 3 Host 109 16. Sternheimer Shielding Factors for Uranium Ions 112 17. General Form of the Crystal-Field Potential for Electrons with I ~ 3 114 18. Anisotropic Interaction Constants for Ce3+ Pairs in LaCl3 and LaBr3 124 19. Theoretical Parameters and Predictions of Allen's Theory of U02 141 20. Parameters of Several Theories of Actinide Spin-Fluctuation Systems 156

xi