Cobalt oxides from crystal chemistry to physics

Bernard Raveau and Md Motin Seikh Cobalt Oxides Related Titles Bersuker, I B Morkoc, H., Özgür, Ü Electronic Structure and Properties of Transition Metal Compounds Zinc Oxide Introduction to the Theory Fundamentals, Materials and Device Technology 2010 2009 Hardcover Hardcover ISBN: 978-0-470-18023-5 ISBN: 978-3-527-40813-9 Duò, L., Finazzi, M., Ciccacci, F (eds.) Jackson, S D., Hargreaves, J S J (eds.) Magnetic Properties of Antiferromagnetic Oxide Materials Metal Oxide Catalysis Surfaces, Interfaces, and Thin Films Hardcover 2010 Hardcover ISBN: 978-3-527-40881-8 Kumar, C S S R (ed.) Nanostructured Oxides 2009 Hardcover ISBN: 978-3-527-32152-0 2009 ISBN: 978-3-527-31815-5 Bernard Raveau and Md Motin Seikh Cobalt Oxides From Crystal Chemistry to Physics The Authors Prof Dr Bernard Raveau Lab CRISMAT CNRS UMR 6508, ISMRA/Universite 6,Bd Du Marechal Juin 14050 Caen Cedex Frankreich Prof Dr Md Motin Seikh Visva-Bharati University Dept of Chemistry Santiniketan West Bengal 731235 Indien All books published by Wiley-VCH are carefully produced Nevertheless, authors, editors, and publisher not warrant the information contained in these books, including this book, to be free of errors Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate Library of Congress Card No.: applied for British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at http://dnb.d-nb.de # 2012 Wiley-VCH Verlag & Co KGaA, Boschstr 12, 69469 Weinheim, Germany All rights reserved (including those of translation into other languages) No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers Registered names, trademarks, etc used in this book, even when not specifically marked as such, are not to be considered unprotected by law Print ISBN: ePDF ISBN: ePub ISBN: mobi ISBN: oBook ISBN: 978-3-527-33147-5 978-3-527-64554-1 978-3-527-64553-4 978-3-527-64555-8 978-3-527-64552-7 Cover Design Formgeber, Eppelheim Typesetting Thomson Digital, Noida, India Printing and Binding Markono Print Media Pte Ltd, Singapore V Contents Preface XI 1.1 1.2 1.3 1.4 1.4.1 1.4.2 1.4.3 1.5 1.6 1.7 1.7.1 1.7.2 1.7.3 1.7.4 1.8 1.8.1 1.8.2 1.8.3 1.8.4 1.8.5 1.8.6 1.9 Introduction Crystal Chemistry of Cobalt Oxides Introduction Stoichiometric Perovskites LnCoO3 Stoichiometric Ln1Àx AxCoO3 Perovskites (A¼Ca, Sr,Ba) Oxygen-Deficient Perovskites: Order–Disorder Phenomena in the Distribution of Anionic Vacancies The Perovskites ACoO3Àd (A-Ca, Sr, Ba) The Sr-Rich Perovskites Sr1xLnxCoO3d 13 The Ordered Oxygen-Decient 112 Perovskites LnBaCo2O5ỵd and LnBaCo2O5.5ỵ d 16 The Ordered Double Stoichiometric Perovskite LaBaCo2O6 18 Hexagonal Perovskite and Derivatives 19 The RP-Type Cobaltites: Intergrowths of Perovskite and Rock Salt Layers and Derivatives 22 Single-Layered RP Phases Ln2ÀxAxxCoO4 (n ¼ 1), with A ¼ Ca, Sr 23 Double-Layered RP Cobaltites: Sr3ÀxLnxCo2O7Àd type 25 RP Derivatives with Double and Triple Rock Salt Layers 29 Tubular Cobaltites 33 Cobaltites with a Triangular Lattice 34 Spinel Cobaltites 34 NaxCoO2-Type Lamellar Oxides 37 The Misfit Cobaltites 45 Intergrowth of Hexagonal Perovskite and CdI2-Type Layers 50 Kagomộ 114 Cobaltites: LnBaCo4O7ỵd and CaBaCo4O7ỵd 51 Unidimensional Cobaltite Ca3Co2O6 58 Some Other Original Cobaltites 59 References 64 VI Contents 2.1 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.2 2.3 2.3.1 2.3.2 2.3.2.1 2.3.2.2 2.3.2.3 2.3.2.4 2.3.2.5 2.3.3 2.3.3.1 2.3.3.2 2.3.3.3 2.3.3.4 2.3.4 2.3.5 2.3.6 2.3.7 2.4 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6 3.2 3.2.1 3.2.1.1 3.2.1.2 3.2.2 Electronic and Magnetic Properties of Stoichiometric Perovskite Cobaltites 71 Stoichiometric LnCoO3 Perovskites 71 Electronic Structure and Spin State Transition 71 Magnetic Properties of LnCoO3 80 Electrical Properties of LnCoO3 82 Magnetoresistance in LnCoO3 85 Phase Separation in LnCoO3 86 Thermoelectric Properties of LnCoO3 87 Ferromagnetism in LaCoO3 Nanoparticles and Thin Films 88 Stoichiometric SrCoO3: Ferromagnetism and Metallic Conductivity 89 Stoichiometric Ln1ÀxAxCoO3 Perovskites (A ¼ Ca, Sr, and Ba) 90 Mixed Valence and Spin State of Cobalt 90 Magnetic Properties of Ln1ÀxAxCoO3 (A ¼ Ca, Sr, and Ba) 93 The Perovskites La1ÀxSrxCoO3 94 The Perovskites La1ÀxAxCoO3 (A ¼ Ca and Ba) 97 Other Ln1ÀxAxCoO3 Perovskites 99 Half-Doped Systems 102 Substitution at Co Sites in La1ÀxAxCoO3 103 Transport Properties of Ln1ÀxAxCoO3 104 The Perovskites La1ÀxSrxCoO3 104 The Perovskites La1Àx(Ca/Ba)xCoO3 106 Other Ln1ÀxAxCoO3 Perovskites 107 Substitution at Co Sites in La1ÀxAxCoO3 108 Charge Ordering in Ln0.5Ba0.5CoO3 Perovskites 109 Magnetoresistance in Ln1ÀxAxCoO3 110 Phase Separation in Ln1ÀxAxCoO3 114 Thermoelectric Power of La1ÀxSrxCoO3 118 The « Ordered » Double Stoichiometric Perovskite LaBaCo2O6 121 References 123 Electronic and Magnetic Properties of Oxygen-Deficient Perovskite Cobaltites Sr1ÀxLnxCoO3Àd and SrCo1ÀxMxO3Àd 129 Disordered Perovskites 129 Magnetic Properties of the Disordered Perovskites Sr1ÀxLnxCoO3Àd 129 Electrical Properties of the Disordered Sr1ÀxLnxCoO3Àd Perovskites 135 224 Ordered Oxygen-Deficient Phases and Brownmillerite 137 Magnetoresistance 142 Phase Separation 145 Thermoelectric Properties 146 Ordered 112 LnBaCo2O5ỵd Perovskites 148 Magnetic Properties 149 LnBaCo2O5 149 LnBaCo2O5.5Ỉd 149 Electron Transport Properties 161 Contents 3.2.2.1 3.2.2.2 3.2.3 3.2.4 3.2.5 3.2.5.1 3.2.5.2 LnBaCo2O5 161 LnBaCo2O5.5Ỉd 162 Phase Separation 168 Magnetoresistance 169 Thermoelectric Properties LnBaCo2O5 172 LnBaCo2O5.5 172 References 175 Electronic and Magnetic Properties of Ruddlesden– Poepper-Type Cobaltites 179 Cobalt Valence and Spin State Transitions 179 Magnetic Properties of RP Phases 185 The n ¼ – RP Cobaltites Ln2ÀxAxCoO4 185 The Half-Doped RP Phase La1.5Sr0.5CoO4 186 The Magnetic Transition Region Around LaSrCoO4 187 The 2D Ferromagnet Sr2CoO4 190 The Sr-Rich Sr2ÀxLnxCoO4 Spin Glass-Like Cobaltites 190 The n ¼ RP Cobaltites 192 Electrical Properties of RP Phases 196 The n ¼ RP Phases Ln2ÀxSrxCoO4 196 The Half-Doped Ln1.5Sr0.5CoO4 Cobaltite 197 The LnSrCoO4 Cobaltites 199 Sr2CoO4 and Some Sr-Rich Phases Sr2ÀxLnxCoO4 200 The n ¼ RP Phases 201 Phase Separation in RP Phases 202 Magnetoresistance of RP Phases 203 Thermoelectric Properties of RP Phases 206 References 209 4.1 4.2 4.2.1 4.2.1.1 4.2.1.2 4.2.1.3 4.2.1.4 4.2.2 4.3 4.3.1 4.3.1.1 4.3.1.2 4.3.1.3 4.3.2 4.4 4.5 4.6 5.1 5.1.1 5.1.2 5.1.2.1 5.1.2.2 5.1.2.3 5.1.2.4 5.1.3 5.2 5.2.1 5.2.2 5.2.3 172 Electronic and Magnetic Properties of Cobaltites with a 3D ‘‘Triangular Lattice’’ 211 The Co3O4 Spinel and Derivatives 211 Valence and Spin States of Cobalt in Bulk Co3O4 211 Magnetic and Transport Properties of Bulk Co3O4 and its Spinel Derivatives 213 Magnetic Properties of Bulk Co3O4 213 Magnetic Properties of Bulk Co3O4 Spinel Relatives 215 Electrical Properties of Co3O4 Spinel 219 Magnetoresistance of Cobalt Spinels 221 Magnetic Properties of Nanodimensional Co3O4 221 The ‘‘114’’ LnBaCo4O7 and CaBaCo4O7 Cobaltites 232 The Cobaltite YBaCo4O7 233 Other LnBaCo4O7 Cobaltites 235 Substitution Effect in YBaCo4O7 at the Cobalt Site 238 VII VIII Contents 5.2.4 5.2.5 The Cobaltite CaBaCo4O7 239 Oxygen Absorption: Oxygen ‘‘Hyperstoichiometry’’ in ‘‘114’’ Cobaltites 241 References 244 Electronic and Magnetic Properties of ‘‘Triangular’’ Layered Cobaltites 249 The Layer Sodium Cobaltites NaxCoO2 250 Valence and Spin States 250 Magnetic Properties of NaxCoO2 and NaxCoO2ÁyH2O 251 Electrical Properties of NaxCoO2 258 Influence of Cobalt Charge and Sodium Ordering upon the Transport and Magnetic Properties of NaxCoO2 260 Magnetoresistance of NaxCoO2 261 Thermoelectric Properties of NaxCoO2 262 Phase Separation in NaxCoO2 266 Superconducting Properties of NaxCoO2ÁyH2O 266 The Electronic Structure of NaxCoO2ÁyH2O 268 Misfit Cobaltites 269 Magnetic Properties of Misfit Cobaltites 269 The n ¼ Members: ‘‘Ca3Co4O9’’ and Relatives 269 The n ¼ Members of the Bi-A-Co-O Systems (A ¼ Ca, Sr, Ba), and [Ca2Co4/3Cu2/3O4]0.62CoO2 272 Electrical Properties of Misfit Cobaltites 274 The n ¼ Members 274 The n ¼ Members 277 Magnetoresistance of Misfit Cobaltites 278 n ¼ Misfits 278 n ¼ Misfits 280 Thermoelectric Properties of Misfit Cobaltites 283 n ¼ Misfit Cobaltites 283 n ¼ – Bismuth-Based Misfit Cobaltites 289 Mechanism of Thermoelectricity in Misfit and Sodium Cobaltites 290 Phase Separation in Misfit Cobaltites 291 References 292 6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6 6.1.7 6.1.8 6.1.8.1 6.2 6.2.1 6.2.1.1 6.2.1.2 6.2.2 6.2.2.1 6.2.2.2 6.2.3 6.2.3.1 6.2.3.2 6.2.4 6.2.4.1 6.2.4.2 6.2.4.3 6.2.4.4 7.1 7.2 7.2.1 7.2.2 7.2.3 7.2.4 7.2.5 Electronic and Magnetic Properties of the ‘‘Unidimensional’’ Cobaltite Ca3Co2o6 297 Valence and Spin State of Cobalt 297 Magnetic Properties of 1D-Ca3Co2O6 and Related Derivatives 299 Anisotropy 303 Frustration 303 Quantum Tunneling 305 Nanophase 307 Models 307 Contents 7.2.6 7.3 7.3.1 7.4 7.5 Index Effect of Substitution at the Cobalt Sites 309 Electrical Resistivity of Ca3Co2O6 and Derivatives 311 Effect of Ca3Co2O6 Doping Upon Resistivity 313 Magnetoresistance of Ca3Co2O6 315 Thermoelectric Power of Ca3Co2O6 and Derivatives 315 References 318 321 IX XI Preface Transition metal oxides represent the most fascinating class of inorganic materials that have been investigated the past 50 years, for a wide range of physical properties such as ferroelectricity in d8-type oxides, high Tc superconductivity in cuprates, or colossal magnetoresistance in manganites Cobalt oxides belong to this family of strongly correlated electron systems, which have been the subject of numerous papers in the recent years, opening the route to new fields of research such as thermoelectricity or multiferroism, and must be regarded as potential materials for applications The exploration of cobalt oxides has demonstrated their extremely high complexity both from the viewpoint of their solid-state chemistry and from the viewpoint of their solid-state physics especially magnetism and transport properties In these oxides, cobalt indeed exhibits several possible valences such as Co2+, Co3+, or Co4+, and intermediate valences, with eventual charge ordering phenomenon Moreover, its extraordinary ability to adopt several types of coordination from tetrahedral, pyramidal, to octahedral makes it an attractive candidate for the generation of numerous structures, with various dimensionalities, 1D, 2D, or 3D, allowing a great flexibility of the oxygen framework, so that oxygen nonstoichiometry is in these compounds a very crucial parameter for the tuning of their physical properties The electronic structure of cobalt, in its various oxidation states, is also a very complex topic, as shown from the possible spin states of cobalt – high spin, low spin, and intermediate spin – which appear in different frameworks and are often a matter of debate for the interpretation of the magnetization of these oxides As a consequence, the physical properties of cobalt oxides, namely, magnetism and transport are extremely rich, ranging from ferro- or ferrimagnetism, to antiferromagnetism, and also magnetic frustration, superconductivity, and even multiferroism These oxides provide an extraordinary range of magnetic and transport transitions that are often coupled with structural transitions, with a high complexity involving in some cases electronic phase separation phenomenon All these properties can be understood only by building a bridge between solid-state chemistry, especially crystal chemistry and solid-state physics Similar to cuprates and manganites, cobaltites provide an excellent direction of research for strongly correlated electron systems, as shown from the abundant literature in this field This monograph provides a presentation of the different structures of cobalt oxides, followed by the electronic ... with the electronic structure of cobalt, its spin state and its valency Then, the following chapters will be devoted to Cobalt Oxides: From Crystal Chemistry to Physics, First Edition Bernard Raveau... (ed.) Nanostructured Oxides 2009 Hardcover ISBN: 978-3-527-32152-0 2009 ISBN: 978-3-527-31815-5 Bernard Raveau and Md Motin Seikh Cobalt Oxides From Crystal Chemistry to Physics The Authors Prof... a magnetic field and photon and/or by tuning the structural parameters (oxygen content and type of countercation) of the material Cobalt Oxides: From Crystal Chemistry to Physics, First Edition