Supermagnets, Hard Magnetic Materials

Transcription

1 Supermagnets, Hard Magnetic Materials

2 NATO ASI Series Advanced Science Institutes Series A Series presenting the results of activities sponsored by the NA TO Science Committee, which aims at the dissemination of advanced scientific and technological knowledge, with a view to strengthening links between scientific communities. The Series is published by an international board of publishers in conjunction with the NATO Scientific Affairs Division A Life Sciences B Physics C Mathematical and Physical Sciences D Behavioural and Social Sciences E Applied Sciences F Computer and Systems Sciences G Ecological Sciences H Cell Biology Plenum Publishing Corporation London and New York Kluwer Academic Publishers Dordrecht, Boston and London Springer-Verlag Berlin. Heidelberg. New York. London. Paris and Tokyo Series C: Mathematical and Physical Sciences - Vol. 331

3 Supermagnets, Hard Magnetic Materials edited by Gary J. Long Department of Chemistry, University of Missouri-Rolla, Rolla, U.S.A. and Fernande Grandjean Institute of Physics, University of Liege, Sart-Tilman, Belgium Springer-Science+Business Media, B.V.

4 Proceedings of the NATO Advanced Study Institute on Supermagnets, Hard Magnetic Materials II Ciocco, Italy June , 1990 ISBN ISBN (ebook) DOI / Printed on acid-free paper All Rights Reserved 1991 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1991 Softcover reprint of the hardcover 1st edition 1991 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic' or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner.

5 T ABLE OF CONTENTS Preface Chapter 1. Historical Background and Introduction to Hard 1 Magnetic Materials. G. J. Long and F. Grandjean Chapter 2. An Outline of the Prehistory of Magnetism. U. Russo 7 and F. Capolongo Chapter 3. Fundamental Concepts and Units in Magnetism. 27 F. Grandjean and G. J. Long Chapter 4. Novel Permanent Magnet Materials. K. H. J. Buschow 49 Chapter 5. Structural Characteristics and Rapid Solidification of N~- 69 Fe 14 B-Type Permanent Magnet Materials. J. F. Herbst Chapter 6. An Introduction to Crystal Field Effects in Magnetism. 95 G. J. Long Chapter 7. Crystal-Field and Exchange Interactions in Hard Magnetic 119 Materials. J. J. M. Franse and R. J. Radwanski Chapter 8. Electronic Structure Calculations for Rare Earth-Transition 133 Metal Compounds. R. Coehoom Chapter 9. Phase Diagrams for Permanent Magnet Materials. E. -Th. 171 Henig and B. Grieb Chapter 10. Intrinsic Properties and Coercivity of Sm-Fe-TM Phases. 227 L. Schultz and M. Katter Chapter 11. Spin-Reorientation Transitions in Intermetallic Compounds. 261 J. Bartolome Chapter 12. Some Nuclear Magnetic Resonance Results on Nd-Fe-B 283 Phases. J.1. Budnick, M. Wojcik, Y. D. Zhang, K. Erdmann, and M. Rosenberg Chapter 13. Domain Wall NMR in Anisotropic Ferromagnets. Applica- 315 tion to the System RE-(CoFe)-B. P. Panissod, M. Wojcik, and E. Jedryka Chapter 14. The Mossbauer Effect and its Application to Hard Perman- 355 ent Magnetic Materials. G. J. Long and F. Grandjean Chapter 15. Thermal, Magnetic, Magnetoelastic, and Transport Charac- 391 terization of Hard Magnetic Alloys. J. Bartolome vii

6 vi Chapter 16. Fundamentals of Magnetic Anisotropy in Rare Earth-Iron Intermetallic Compounds. N. C. Koon, C. M. Williams, andb. N. Das 415 Chapter 17. Crystal Fields in Y _ Er Fe 14 B from Magnetic Torque Measurements. N. t!: Kton, C. M. Williams, and B. N. Das 431 Chapter 18. Determination of the Anisotropy Field by the Singular 449 Point Detection Method. H. Kirchmayr Chapter 19. Micromagnetic Background of Hard Magnetic Materials. 461 H. Kronmiiller Chapter 20. Neutron Spectroscopy and Magnetic Excitations in Super- 499 magnets. O. Moze Chapter 21. Structure and Properties of Ternary Fe-Rich Rare Earth 527 Carbides. K. H. J. Buschow Chapter 22. Metastable Phases and their Role in Permanent Magnet 553 Manufacturing. K. H. J. Buschow Chapter 23. Preparation and Properties of Mechanically Alloyed 573 Nd-Fe-B Magnets. L. Schultz Chapter 24. Review of Permanent Magnet Applications and the 585 Potential for High Energy Magnets. D. Howe Chapter 25. Magnet Design and Analysis Techniques. D. Howe, M. 617 K. Jenkins, and W. F. Low Chapter 26. Permanent Magnet Machines. D. Howe and T. S. Birch 679 Chapter 27. Design and Performance of Synchronous Motors with 703 Nd-Fe-B Magnets. B. J. Chalmers Chapter 28. Alternative Topologies of Brushless DC Machines for 723 Power Applications. B. J. Chalmers, A. Sitzia, and E. Spooner Chapter 29. Electrical Machine Design with Combined Field-Coil and 743 Magnet Excitation. E. Spooner and B. J. Chalmers Chapter 30. Simulation of Permanent Magnet Motor Drives. D. Howe, 757 M. K. Jenkins, and Z. Q. Zhu Appendix List of ASI Participants. 791 Author Index 795 Subject Index 809

7 Preface The book you are now holding represents the final step in a long process for the editors and organizers of the Advanced Study Institute on hard magnetic materials. The editors interest in hard magnetic materials began in 1985 with an attempt to better understand the moments associated with the different iron sites in Nd Fe 14 B. These moments can be obtained from neutron diffraction studies, but we quickly realized that iron-57 Mossbauer spectroscopy should lead to a better determination of these moments. However, it was also realized that the complex Mossbauer spectra obtained for these hard magnetic materials could not be easily understood without a broad knowledge of their various structural, electronic, and magnetic properties. Hence it seemed useful to the editors to bring together scientists and engineers to discuss, in a tutorial setting, the various properties of these and future hard magnetic materials. We believe the inclusion of engineers as well as scientists in these discussions was essential because the design of new magnetic materials depends very much upon the mode in which they are used in practical devices. The actual organization of this ASI began at the Paris International Conference on Magnetism, in July During this conference the editors first discussed a possible ASI with Prof. K. H. J. Buschow and Dr. N. Koon, who subsequently joined the international organizing committee. They also contacted several other scientists, who agreed to lecture at the AS!. Further discussion of the ASI with Dr. J. F. Herbst occured during the Rare-Earth Research Conference at Lake Geneva, Wisconsin, in October Subsequently invitations to lecture were extended to about 20 scientists and engineers from various NATO countries. After further fruitful discussions with Prof. Buschow, the final proposal for the ASI was submitted to NATO in January The organizers learned that NATO would provide fundings for the ASI in Apri11989, and the final organization of the Institute took place at the Boston Magnetism and Magnetic Materials Conference, in November This schedule probably represents the ideal timetable for the organization of such an AS!. The organization of an ASI provides an opportunity to study human nature in the scientific community. Some scientists and engineers read their mail, promptly respond, and even provide their lecture notes and chapters before the established deadline. Others just barely respor.d, and use the fax to meet the deadlines. Still others, fortunately the fewest in number, don't even open their mail, especially mail which arrives in brown envelopes and appears to be junk mail, and only respond after repeated requests from the organizers. So, in this respect, scientists and engineers mirror the behavior seen in the world at large. However, in the end, each of the invited participants gave their lectures just as scheduled and all the lecturers, except one, have provided chapters for this volume. In addition to the lecture schedule, the organizing committee also has the responsibility of publicizing the ASI and attracting young scientists and engineers to participate in the Institute. For us, this task was the most difficult part of the organization and perhaps the least succesful. However, we believe that the 45 student participants benefited greatly from their interaction with the invited lecturers. Further we believe that 60 to 70 participants and lecturers may represent the ideal size for an AS!. The international nature of hard permanent magnets research is reflected in the 16 nations on four continents, which were represented at the meeting. The participants at this ASI thoroughly enjoyed the excellent weather, beautiful scenery, and the superb food and gracious hospitality provided by the staff at the II Ciocco International Center, which is located sixty-five kilometers north of Pisa in the splendid Sercchio valley of Tuscany. In addition to the many hours of hard work in the vii

8 viii lecture hall, the participants made good use of the swimming pool and athletic facilities. The mountains of Tuscany provided excellent opportunities for weekend hikes to such nearby picturesque mountain villages as Treppignana and Barga. We believe the participants will long remember the beautiful view of Barga in the sunset from the terrace of 11 Ciocco. The evenings during the ASI were made especially exciting by the ltalia-90 world cup football matches, the results of which were announced at the beginning of the morning sessions. Other evenings were enhanced by a wine tasting party and a farewell dinner with several award presentations, including a special award to Dr. R. Coehoorn for the most well received lecture. Special mention goes to Dr. P. Panissod for his list of over 500 permanent magnets used throughout his typical day. Finally, the editors would like to thank the organizing committee and especially Profs. K. H. J. Buschow and U. Russo for many helpful suggestions and each of the authors for their timely and informative chapters. The editors also thank Ms. S. Maquet, of University of Liege, and Mr. B. Giannassi, of n Ciocco, for their help in the ASI organization, and Ms. C. Perilleux, of Liege, and Mr. Jason Giles, of University of Missouri-Rolla, for their help in preparing the indexes. Of course, this ASI could not have taken place without the financial support provided by the NATO Scientific Affairs Division. We also gratefully acknowledge support provided by the University of Liege, the University of Missouri-Rolla, CNR ofitaly, and FIAT. October 1990 Gary J. Long Fernande Grandjean