Mossbauer Spectroscopy Applied to Inorganic Chemistry Volume 1

MODERN INORGANIC CHEMISTRY

Series Editor: John P. Fackler, Jr. Texas A&M University

METAL INTERACTIONS WITH BORON CLUSTERS Edited by Russell N. Grimes

HOMOGENEOUS CAT AL YSIS WITH METAL PHOSPHINE COMPLEXES Edited by Louis H. Pignolet

THE lAHN-TELLER EFFECT AND VIBRONIC INTERACTIONS IN MODERN CHEMISTRY I. B. Bersuker

MOSSBAUER SPECTROSCOPY APPLIED TO INORGANIC CHEMISTRY, Volume 1 Edited by Gary 1. Long

CARBON-FUNCTIONAL ORGANOSILICON COMPOUNDS Edited by Vaclav Chvalovsky and Jon M. Bellama

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

Applied to Inorganic Chemistry Volume 1

Edited by

Gary J. Long University of Missouri-Rolla Rolla, Missouri

SPRINGER SCIENCE+BUSINESS MEDIA, LLC

Mössbauer Spectroscopy

Library of Congress Cataloging in Publication Data

Main entry under title:

Mossbauer spectroscopy applied to inorganic chemistry.

(Modern inorganic chemistry) Includes bibliographies and index. 1. Mossbauer spectroscopy. I. Long, Gary J., 1941-

QD96.M6M64 1984 543' .08586

© 1984 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1984 Softcover reprint of the hardcover 1 st edition 1984

All rights reserved

.11. Series. 84-13417

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

ISBN 978-1-4899-0464-5 ISBN 978-1-4899-0462-1 (eBook) DOI 10.1007/978-1-4899-0462-1

Contributors

Frank J. Berry Department of Chemistry University of Birmingham Birmingham B 15 2TT England

J.M.D. Coey Department of Pure and Applied Physics Trinity College University of Dublin Dublin 2 Ireland

T.E. Cranshaw Nuclear Physics Division Atomic Energy Research Establishment Harwell, Didcot, Oxfordshire OXII ORA England

D.P.E. Dickson Department of Physics University of Liverpool Oxford Street Liverpool L69 3BX England

P. Gutlich Institut fUr Anorganische und Analytische Chemie J ohannes-Gutenberg-U ni versiUit D-6500 Mainz West Germany

vi

Gilbert R . Hoy Department of Physics Old Dominion University Norfolk Virginia 23508

C.E. Johnson Department of Physics University of Liverpool Oxford Street Liverpool L69 3BX England

Gary J. Long Department of Chemistry University of Missouri-Rolla Rolla Missouri 65401

Geoffrey Longworth Nuclear Physics Division Atomic Energy Research Establishment Harwell, Didcot, Oxfordshire OXI lORA England

R.V. Parish Department of Chemistry The University of Manchester

Institute of Science and Technology Manchester M60 I QD England

William M. Reiff Department of Chemistry Northeastern University Boston Massachusetts 02115

Contributors

Contributors

Gopal K. Shenoy Materials Science and Technology Division Argonne National Laboratory Argonne Illinois 60439

Hartmut Spiering Institut fUr Anorganische und Analytische Chemie J ohannes-Gutenberg-U niversiHit D-6500 Mainz West Germany

vii

Preface

When presented with a new compound or material, the inorganic chemist will usually have several questions in mind about its composition and structure. Although a simple elemental analysis may answer many questions about its composition, the chemist will still have questions about its structure, and, ifthe material contains a metal atom, he will often want to know its oxidation state, coordination number and geometry. Further, at an increasingly frequent rate, the chemist may need details of the spin­state, magnetic and perhaps dynamic properties of the material. If the investigator is fortunate, the material or compound may contain an ele­ment such as iron, tin, antimony, iodine, gold, or one of several of the rare earth metals which are amenable to study by the Mossbauer effect. Often the Mossbauer effect can, sometimes with quite simple experiments, provide the answers to all of these questions.

The goal of this book is to illustrate the effectiveness of the Mossbauer effect in providing the answers to the many questions that arise in char­acterizing new materials and, indeed, in studying known materials in more detail. Several chapters introduce the effect to the novice and provide details about the various hyperfine interactions that are the "bread and butter" of the Mossbauer spectroscopist. Three chapters deal specifically with the experimental aspects of the technique and the increasing impor­tance of sophisticated computer analysis of the resulting data. Subsequent chapters deal with the application of the Mossbauer effect to specific problems of interest to chemists in particular and often to metallurgists, geologists, biologists, and physicists as well.

As the Mossbauer effect enters its second quarter century, the editor, and I am sure, the Mossbauer community as a whole, owe a great deal of thanks to the efforts of John and Virginia Stevens. As will be noted in subsequent chapters, their efforts have made the Mossbauer effect data index one of the best in the world. Inevitably, one of the early steps in any Mossbauer effect study is a visit to the library to check the index. Thanks to John and Virginia this visit is usually short and always pleasant.

As is so often the case, the editor of a volume such as this owes

ix

x Preface

many thanks to his fellow authors, colleagues, and students. I would like to thank each of the authors for finding time in their busy schedules of teaching, research, administration, and travel, to contribute to this effort. Special credit and thanks is due to Geoff Longworth for his help in the early planning of the contents of this volume and to both Geoff and Ted Cranshaw for their continued encouragement and patience in introducing me to many of the fine points of Mossbauer spectroscopy. Further thanks go to Jack Fackler for first suggesting this volume and to Ellis Rosenberg for his help in seeing this project come to fruition. The completion of this work was greatly assisted by Chris Benson and Ms. Carol Rodman, and in the end by Jeff and Audrey Long who devoted many long hours to the preparation of the index. Finally, I thank Dominic Dickson, Ian Hall, Mike Thomas, and Charles Johnson for their fine hospitality during a delightful sabbatical in England.

Liverpool April 1984

Gary J. Long

Contents

Chapter 1. Introduction and Historical Background Gary J. Long

References ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Chapter 2. Basic Concepts of Mossbauer Spectroscopy Gary J. Long

1. Mossbauer-Effect Spectroscopy ............................ 7 1.1. Radiation Source .................................... 9 1.2. Elements Amenable to Study...................... 14 1.3. Energy Dispersion .................................. 15 1.4. Mossbauer-Effect Absorbers....................... 16 1.5. Radiation Detector.................................. 18 1.6. Data Storage and Presentation..................... 19 1.7. Spectrometer Calibration ........................... 19

2. Interpretation of Mossbauer Spectra ....................... 20 2.1. Mossbauer-Effect Isomer Shift .................... 20 2.2. Nuclear Quadrupole Interaction................... 22 2.3. Nuclear Zeeman Splitting .......................... 23 References .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Chapter 3. Mossbauer Spectrometers and Calibration T.E. Cranshaw

1. Mossbauer Spectrometers ................................... 27 2. Data Collection .............................................. 30 3. Specialized Spectrometers .................................. 32 4. Counting Chain .............................................. 32 5. Detectors for Transmission Spectra........................ 33 6. Detectors for Backscatter Spectra .......................... 35

6.1. X-ray Detection ..................................... 37 6.2. Electron Detection.................................. 37

7. Calibration of the Velocity Scale ........................... 38 8. Absolute Calibration ......................................... 38

xi

xii Contents

9. Note on Folding Symmetrical Spectra ..................... 40 References ................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Chapter 4. Spectral Data Reduction and Refinement Geoffrey Longworth

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 2. Least-Squares Minimization Fitting Routines ............. 44 3. Goodness of Fit Criteria .................................... 48 4. Transmission Integral ........................................ 49 5. Use of Interaction Hamiltonians ............................ 51 6. Overlapping Hyperfine Distributions ....................... 52 7. Stripping Techniques ........................................ 53 8. Programs for Use on Microcomputers ..................... 54

References ................................................... 54

Chapter 5. Mossbauer-Effect Isomer Shifts G.K. Shenoy

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 2. Basic Features ............................................... 58 3. Calibration of the Isomer Shift ............................. 60

3.1 Free-Ion Atomic Calculations of p(O) ............. 61 3.2. Experimental Aids in Isomer Shift Calibration ... 63

4. Chemical Applications of the Isomer Shift ................ 65 4.1. Oxidation State ..................................... 65 4.2. Bond Character ..................................... 67 4.3. The Spectrochemical Series........................ 68 4.4. Isoelectronic and Isovalent Pairs .................. 70 4.5. Beyond the Free-Ion Calculations of p(O) ........ 71 4.6. Relation to Quadrupole Interaction ................ 72

5. Summary..................................................... 74 Acknowledgments ...................................... ..... 74 References ................................................... 74

Chapter 6. The Electric Field Gradient and the Quadrupole Interaction Hartmut Spiering

1. The Quadrupole Interaction ................................. 79 2. The Line Positions of a Mossbauer Spectrum............. 83

2.1. The Eigenvalues of the Spin Hamiltonian ........ 83 2.2. The Information Obtained from the Line

Positions ............................................. 87 3. The Intensities of the Mossbauer Absorption Spectra .... 89

3.1. The Matrix Formulation............................ 89 3.2. The Intensity Matrix of a Single Transition....... 102

Contents xiii

3.3. Texture.............................................. 107 3.4. Goldanskii-Karyagin Effect ........................ 118

4. Application of the Theory to Thin Absorbers ............. 123 4.1. Powder Spectra ..................................... 125 4.2. Single Crystals ...................................... 139

5. Application of the Theory to Thick Absorbers ............ 149 5.1. The Polarization Effect of Thick Crystals ........ 153 5.2. Thick Single Crystals of Orthorhombic and

Monoclinic Symmetry (3/2~ 112 Transition) ...... 155 5.3. A Polarized Source .......................... ....... 165 List of Symbols.... .......................................... 168 References ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Chapter 7. Mossbauer Spectroscopy of Magnetic Systems T.E. Cranshaw and G. Longworth

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 2. The Nuclear Zeeman Effect ................................ 171

2.1. Energy Levels ...................................... 171 2.2. Intensity Considerations ........................... 173

3. The Field Seen by the Nucleus............................. 174 3.1. Components of the Effective Field................ 174 3.2. The Effective Field ................................. 175

4. Examples 4.1. MnF2 ................................................. 182 4.2. An Orthoferrite ..................................... 184 4.3. Magnetite (Fe304) ................................... 185 4.4. Haematite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 4.5. Ferric Phosphate.................................... 190 4.6. Ferric Sulfate ....................................... 190 Acknowledgments ........................................... 193 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

Chapter 8. Relaxation Phenomena for Chemists Gilbert R. Hoy

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 2. Elementary Considerations ................................. 196 3. Stochastic Model of Relaxation............................. 200 4. Specific Previous Examples ................................. 203 5. Representative Calculations U sing the Clauser-Blume

Theory........................................................ 209 6. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

Acknowledgments ........................................... 222 References ......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

xiv Contents

Chapter 9. X-Ray and Conversion Electron Mossbauer Scattering for Chemists

Geoffrey Longworth I. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 2. Oxidation and Corrosion Studies ........................... 228 3. Metallurgical Studies of Steel Surfaces .................... 232 4. Studies on Thin Films ....................................... 236 5. Studies ofIon-Implanted Alloys............................ 236

References ................................................... 242

Chapter 10. Mossbauer Spectroscopy and the Coordination Chemistry of Iron

William M. Reiff and Gary J. Long I. Solid-State Thermolytic Preparations ...................... 245 2. Studies of Cooperative Structural Phase Transformation 251

2.1. Order-Disorder of High Symmetry Lattice Anions............................................... 251

2.2. Phase Transitions in Linear Chain Plymers ....... 255 2.3. Phase Transitions in Nonlinear Chain Polymers 267 2.4. Phase Transformations in Two-Dimensional

Layer Compounds .................................. 268 3. Studies of Magnetic Phase Transitions..................... 273

Acknowledgments ........................................... 283 References ................................................... 283

Chapter II. Spin Transition in Iron Complexes P. Giitlich

I. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 2. Spin Transition in [Fe(phenh(NCShl ...................... 291

2.1. Magnetic Effect of Ligand Replacement in [Fe(phenhY21 Complexes .......................... 291

2.2. Spin Transition Properties of Polycrystalline [Fe(phenhCNCShl .................................. 292

2.3. Influences on the Spin Transition Behavior of [Fe(phenhCNCShl .................................. 295

3. Spin Transition in [Fe(2-pichlX2·Sol ....................... 306 3.1. Early Studies on the Magnetism

of [Fe(2-pich]X2 •••••••••••••••••••••••••••••••••••• 306 3.2. Spin Transition Properties of

Solid [Fe(2-pich]clz· EtOH ......................... 307 3.3. Influences on the Spin Transition Characteristics

in [Fe(2-pichlCI2 ·Sol ................................ 310 4. Spin Transition in Other Iron(Il) Complexes .............. 321

Contents xv

4.1. [Fe(Y -phenh]X2 Complexes; Effect of Intraligand Substitution ......................................... 322

4.2. Bis (thiazoline) Complexes of the Type [FeL2X2] 327 4.3. [FeL6]X2 Complexes with Monodentate Ligands 328

5. Spin Transition in Iron(III) Complexes .................... 333 References .................................. . . . . . . . . . . . . . . . . . 334

Chapter 12. Applications to Biological Systems D.P.E. Dickson

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339 2. Special Problems.. ....... ..................... ....... .. .. .... 342

2.1. Sample Requirements .............................. 342 2.2. Data Analysis ....................................... 344

3. Applications to Isolated Biomolecules ..................... 345 3.1. Heme Proteins ...................................... 345 3.2. Iron-Sulfur Proteins ................................ 351 3.3. Iron Transport Compounds ........................ 364 3.4. Iron Storage Compounds........................... 364 3.5. Iodine Compounds.................................. 367 3.6. Vitamin BI2 .......................................... 367

4. Applications to Enzymes and Related Systems ........... 368 4.1. Nitrogenase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 4.2. Oxygenase........................................... 370 4.3. Hydrogenase........................................ 371 4.4. Cytochrome P450-Ferredoxin Enzyme System... 372 4.5. Photosynthetic Reaction Centers .................. 373

5. Medical and Physiological Applications.................... 374 5.1. Blood Disorders..................................... 374 5.2. Lung Samples....................................... 377 5.3. Bone Samples....................................... 379 5.4. Uptake and Metabolism Experiments............. 379

6. Measurements of Vibration and Movement ................ 381 6.1. Protein Dynamics ................................... 382 6.2. Macroscopic Movement ............................ 384

7. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385

Chapter 13. Mossbauer Spectroscopy in Heterogeneous Catalysis Frank 1. Berry

1. Introduction.................................................. 391 2. Suitability of Mossbauer Spectroscopy for the Study of

Catalytic Solids .............................................. 392 2.1. Inherent Advantages of the Technique ............ 392

xvi Contents

2.2. Potential for in Situ Studies ........................ 393 2.3. Investigations Using Transmission,

Backscattering, and Source Techniques .......... 395 3. Applications of Mossbauer Spectroscopy to the Study of

Catalysts ...................................................... 399 3.1. Supported metal Catalysts ......................... 399 3.2. Promoted Catalysts ................................. 412 3.3. Bimetallic Catalysts ................................ 413 3.4. Mixed Oxide Catalysts ............................. 417 3.5. Hydrodesulfurization Catalysts .................... 428 3.6 Zeolite Catalysts .................................... 431

4. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 References ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

Chapter 14. Mossbauer Spectroscopy of Silicate Minerals 1.M.D. Coey

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443 2. Interpretation of the Mossbauer Spectra of Minerals ..... 447 3. Iron Site Preference ......................................... 459

3.1. Framework Silicates................................ 459 3.2. Sheet Silicates ...................................... 460 3.3. Chain Silicates ...................................... 465 3.4. Group Silicates...................................... 473

4. Natural and Artificial Transformations ..................... 479 4.1. Natural Transformations ........................... 479 4.2. Artificial Transformations .......................... 483

5. Electron Hopping ............................................ 485 6. Magnetic Order .............................................. 490 7. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497

Acknowledgments ........................................... 498 Glossary of Silicate Minerals ............................... 499 References .................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503

Chapter 15. Studies of Ceramics and Archaeological Materials Geoffrey Longworth

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 2. Transformations in Clays on Firing ........................ 513 3. Characterization of Pottery Samples ....................... 515 4. Studies of Surface Glazes ................................... 517 5. Age of Pottery ............................................... 518 6. Characterization of Obsidian ................................ 520 7. Soils at Archaeological Sites ................................ 523

References ........................ . . . . . . . . . . . . . . . . . . . . . . . . . . . 525

Contents xvii

Chapter 16. Structure and Bonding in Tin Compounds R. V. Parish

1. Basic Considerations ........................................ 527 2. Quadrupole Splitting in Structure Determination.......... 528

2.1. Fundamentals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528 2.2. Recent Structure Determinations.................. 530 2.3. The Partial Quadrupole Splitting Parametrization

Method .............................................. 534 2.4. Choice of PQS Scales .............................. 539 2.5. Effects of Distortion................................ 544

3. Recoil-Free Fraction......................................... 549 3.1. Temperature Dependence of the Recoil-Free

Fraction ............................................. 549 4. Matrix-Isolation Studies ..................................... 555 5. Calibration of Isomer-Shift and Quadrupole-Splitting

Scales......................................................... 556 6. Tin(II) Systems .............................................. 558 7. Metal Complexes of Tin(II) Ligands ....................... 564

Abbreviations ................................................ 569 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572

Chapter 17. Gold-197 Mossbauer Spectroscopy in the Characteriza­tion of Gold Compounds

R.V. Parish 1. Introduction .................................................. 577 2. Properties of 197 Au ........................................... 577 3. Practical Aspects ............................................ 579 4. Gold(I) ........................................................ 580

4.1. Two-Coordination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580 4.2. Higher Coordination Numbers ..................... 585 4.3. Applications......................................... 588 4.4. Partial Center Shifts and Quadrupole Splittings .. 589

5. Gold(III) ...................................................... 594 5 .1. Four-Coordination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594 5.2. Applications......................................... 597

6. Gold(I1) and Mixed-Valence Systems ...................... 598 7. Gold(V) ....................................................... 603 8. Cluster Compounds .......................................... 603 9. Intermetallic Compounds .................................... 606

to. Recoil-Free Fraction......................................... 609 11. Correlation of Mossbauer Parameters with Electron

Configuration................................................. 611 12. Conclusion ................................................... 613

xviii Contents

Abbreviations ................................................ 614 References ................................................... 614

Chapter 18. One-Dimensional Magnetism c.E. Johnson

I. Introduction .................................................. 619 2. ID Antiferromagnetic Ordering ............................. 620 3. Zero-Point Spin Reduction in Antiferromagnets ........... 621 4. Spin-Wave Theory........................................... 623 5. Sublattice Magnetization .................................... 626 6. Experimental Techniques ................................... 627

6.1. Magnetic Susceptibility ............................. 627 6.2. Heat Capacity ....................................... 627 6.3. Inelastic Neutron Scattering ....................... 627 6.4. Magnetic Hyperfine Interactions .................. 627

7. Mossbauer-Effect Measurements........................... 628 7.1. ID Crystal Structure ................................ 628 7.2. Mossbauer Spectra in Zero Applied Field ........ 629 7.3. Mossbauer Spectra in Applied Fields ............. 632

8. Change in TN with Applied Field ........................... 634 8.1. B Parallel to M ...................................... 634 8.2. B Perpendicular to M ............................... 635

9. Saturation Value of Bhf .•.••.••.•.••.•.•••••••.••.••••••••••• 635 9.1. B Parallel to M ...................................... 635 9.2. B Perpendicular to M ............................... 635

10. Solitons ....................................................... 636 II. Conclusion ................................................... 639

References ................................................... 639

Author Index ........................................................... 641

Subject Index .......................................................... 655