Table Of ContentMODERN FERRITE TECHNOLOGY
SECOND EDITION
MODERN FERRITE TECHNOLOGY
SECOND EDITION
Alex Goldman
Pittsburgh, PA, USA
^ Springer
Alex Goldman
Ferrite Technology
Pittsburgh, PA, USA
Modem Ferrite Technology, 2""^ Ed
Library of Congress Control Number: 2005933499
ISBN 10: 0-387-28151-7
ISBN 13: 978-0-387-28151-3
ISBN 10: 0-387-29413-9 (e-book)
Printed on acid-free paper.
© 2006 Springer Science+Business Media, Inc.
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Dedication
This book is dedicated to the memory of Professor Takeshi Takei.
Professor Takei, to whom I dedicated the first edition of this book and whose
preface to that book follows this dedication, was a greatly loved friend and teacher
of mine. He passed away on March 12, 1992. He will be remembered as a founding
father of ferrites, a great teacher and the organizer of ICF (International Conference
on Ferrites). Prof. Takei can truly be regarded as the "father of Modern Ferrites". In
addition to his pioneering efforts in the early 1930's, he was a guiding light as a
teacher of young scientists and engineers and an inspiration to use one's
imagination and work hard. He is sorely missed by the whole ferrite community
Table of Contents
Forward by Takeshi Takei xi
Preface xi
Preface to Second Edition xiii
Acknowledgements xv
Chapter 1: Basics of Magnetism—Source of Magnetic Effect 1
Introduction 1
Magnetic Fields 1
The Concept of Magnetic Poles 2
Electromagnetism 5
Atomic Magnetism 5
Paramagnetism and Diamagnetism 9
Ferromagnestism 10
Antiferromagnetism 11
Ferrimagnetism 13
Paramagnetism above the Curie Point 14
Summary 14
Chapter 2: The Magnestization in Domains and Bulk Materials 17
Introduction 17
The Nature of Domains 17
Proof of the Existence of Domains 21
The Dynamic Behavior of Domains 23
Bulk Material Magnetization 24
MKSA Units 28
Hysteresis Loops 28
Permeability 30
Magnetocrystalline Anisotropy Constants 31
Magnetostriction 32
Important Properties for Hard Magnetic Materials 33
Summary 34
Chapter 3: AC Properties of Ferrites 35
Introduction 35
AC Hysteresis Loops 35
Eddy Current Losses 35
Permeability 38
Disaccomamodation 42
Core Loss 43
Microwave Properties 44
Microwave Precessional Modes 47
Logic and Switching Properties of Ferrites 48
viii MODERN FERRITE TECHNOLOGY
Properties of Recording Media 49
Summary 49
Chapter 4: Crystal Structure of Ferrites 51
Introduction 51
Classes of Crystal Structures in Ferrites 51
Hexagonal Ferrites 63
Magnetic Rare Earth Garnets 65
Chapter 5: Chemical Aspects of Ferrites 71
Intrinsic and Extrinsic Properties of Ferrites 71
Magnetic Properties Under Consideration 71
Mixed Ferrites for Property Optimization 72
Temperature Dependence of Initial Permeability 89
Time Dependence—Initial Permeability (Disaccomodation) 92
Chemistry Dependence—Low Field Losses (Loss Factor) 93
Chemistry Considerations for Hard Ferrites 104
Saturation Induction—^Microwave Ferrites and Garnets 104
Ferrites for Memory and Recording Applications 106
Chapter 6: Microstructural Aspects of Ferrites Ill
Introduction Ill
Summary 146
Chapter 7: Ferrite Processing 151
Introduction 151
Powder Preparation—Raw Materials Selection 151
Nonconventional Processing 163
Nanocrystalline Ferrites 166
Powder Preparation of Microwave Ferrites 174
Hard Ferrite Powder Preparation 175
Chapter 8: Applications and Functions of Ferrites 217
Introduction 217
History of Ferrite Applications 217
General Categories of Ferrite Applications 218
Ferrites at D.C. Applications 219
Power Applications 219
Entertainment Applications 221
High Frequency Power Supplies 223
Microwave Applications 224
Magnetic Recording Applications 224
Miscellaneous Applications 226
Summary 226
Chapter 9: Ferrites for Permanent Magnetic Applications 227
Introduction 227
History of Permanent Magnets 227
General Properties of Permanent Magnets 228
TABLE OF CONTENTS ix
Types of Hard Ferrites Materials 232
Criteria for Choosing a Permanent Magnet Material 232
Stabilization of Permanent Magnets 237
Cost Considerations in Permanent Magnet Materials 237
Cost of Finished Magnets 238
Optimum Shapes of Ferrite and Metal Magnets 238
Recoil Lines—Operating Load Lines 238
Commercial Oriented and Non—Oriented Hard Ferrites 238
Summary 242
Chapter 10: Ferrite Inductors and Transformers for Low Power Applications243
Introduction 243
Inductance 244
Effective Matnetic Parameters 245
Measurements of Effective Permeability 247
Magnetic Considerations: Low-Level Applications 248
Flux Density Limitations in Ferrite Inductor Design 260
Surface—Mount Design for Pot Cores 262
Low Level Transformers 262
Ferrites for Low—Level Digital Applications 266
ISDN Components and Materials 268
Low Profile Ferritecores for Telecommunications 269
Multi-Layer Chip Inductors and LC Filters 270
Chapter 11: Ferrites for EMI Suppression 273
Introduction 273
The Need for EMI Suppression Devices 273
Materials for EMI Suppression 275
Frequency Characteristics of EMI Materials 278
The Mechanism of EMI Suppression 279
Components for EMI Suppression 281
Differential Mode Filters 286
Chapter 12: Ferrites For Entertainment Applications—Radio and TV 291
Introduction 291
Ferrite TV Picture Tube Deflection Yokes 291
Materials for Deflection Yokes 293
Flyback Transformers 297
General Purpose Cores for Radio and Television 299
Ferrite Antennas for Radios 300
Summary 306
Chapter 13: Ferrite Transformers and Inductors at High Power 307
Introduction 307
The Early Power Applications of Ferrites 307
Power Transformers 308
Frequency—Voltage Considerations 308
Frequency—Loss Considerations 309
The Hysteresis Loop for Power Materials 310
X MODERN FERRITE TECHNOLOGY
Inverters and Converters 312
Choosing the Right Component for a Power Transformer 313
Choosing the BestFerrite Material 314
Permeability Considerations 318
Output Power Considerations 319
Power Ferrites VS Competing Magnetic Materials 320
Power Ferrite Core Structures 320
Planar Technology 330
High Frequency Applications 324
Determining the Size of the Core 324
Aids in Power Ferrite Core Design 324
Competitive Power Materials for High Frequency 346
Ferroresonant Transformers 347
Power Inductors 348
Chapter 14: Ferrites for Magnetic Recording 353
Introduction 353
Other Digital Magnetic Recording Systems 358
Magnetic Recording Media 361
Magnetic Recording Heads 362
Magnetoresistive Heads 362
Chapter 15: Ferrites for Microwave Applications 375
Introduction 375
The Need for Ferrite Microwave Components 375
Ferrite Microwave Components 376
Commercially Available Microwave Materials 384
Summary 384
Chapter 16: Miscellaneous Ferrite Applications 387
Introduction 387
Summary 393
Chapter 17: Physical, Mechanical and Thermal Aspects of Ferrites 395
Introduction 396
Summary 401
Chapter 18: Magnetic Measurements on Ferrite Materials and Components.403
Introduction 403
Measurements of Magnetic Field Strength 403
Appendix 1 427
Appendix! 433
Index 435
FOREWORD
Below is a copy of Professor Takeshi Takei's original preface that he wrote for my
first book, Modern Ferrite Technology. I was proud to receive this preface and
include it here with pride and affection. We were saddened to learn of his death at
92 on March 12, 1992.
Preface
It is now some 50 years since ferrites debuted as an important
new category of magnetic materials. They were prized for a range of
properties that had no equivalents in existing metal magnetic
materials, and it was not long before full-fledged research and
development efforts were underway. Today ferrites are employed in
a truly wide range of applications, and have contributed materially
to advances in electronics. Research, too, continues apace, and the
efforts of the many men and women working in the field are yielding
many highly intriguing results. New, high-performance products
are appearing one after another, and it would seem we have only
scratched the surface of the hidden possibilities of these fascinating
materials.
Dr. Alex Goldman is well qualified to talk about the state of the
art in ferrites. For many years Dr. Goldman has been heavily
involved in the field as the director of the research and development
division of Spang & Co. and other enterprises. This book, Modern
Ferrite Technology, based in part on his own experiences, presents a
valuable overview of the field. It is testimony to his commitment
and bountiful knowledge about one of today^s most intriguing areas
of technology.
In the first part of the book, Dr. Goldman discusses the static
characteristics of ferrites based on the concept of ferrimagnetism.
He then considers their dynamic properties in high-frequency
magnetic fields.
Dr. Goldman follows this up with a more detailed look at some
of these characteristics. In a section on power materials he
examines the need to use chemical adjustment and microstructural
optimization to attain high saturation and low core loss at high
xii MODERN FERRITE TECHNOLOGY
frequencies. He uses anisotropy and fme particle concepts to
describe permanent magnetic ferrites, and reviews how
gyromagnetic properties help explain the actions of microwave
ferrites.
In a section on applications, he introduces such production
technologies-some conventional, some unconventional-as
coprecipitation, spray roasting and single crystal preparation. He
also discusses some of the special difficulties that ferrites can pose
from a design point of view in actual applications. Turning to the
subject of magnetic recordings, Dr. Goldman discusses in detail the
impressive strides being made in magnetic media and magnetic
head applications.
The book is rounded out with valuable appendices, including
listings of the latest physical, chemical and magnetic data available
on ferrites and listings of world ferrite suppliers.
Modern Ferrite Technology presents the reader with the latest
thinking on ferrites by the scientists, researchers and technicians
actually involved in their development, leavened with the rich
experiences over many years of the author himself. It is a work of
great interest not only to those researching new ferrite materials
and applications, but to all in science and industry who use ferrites
in their work.
April 1987
Takeshi Takei
