Oxygen Disorder Effects in High-T c Superconductors PDF
Preview Oxygen Disorder Effects in High-T c Superconductors
Oxygen Disorder Effects in High-Tc Superconductors Oxygen Disorder Effects in High-Tc Superconductors Edited by J. L. Moran-Lopez Universidad Aut6noma de San Luis POtOSI San Luis Potosi, San Luis POtOSI Mexico and Ivan K. Schuller University oj California, San Diego La Jolla, California Plenum Press • New York and London LIbrary of Congress C.~aloglng-In-Publlc.tlon Data ~xygen dlsorder effecTs in high-Tc sucerconduCTO~S I edited by J.L. ~orin-L6pez and Ivan K. Schuller. p. em. In:ludes bibl10graphical references. lSBN-13: 978-1-4612-7867-2 e-lSBN-13: 978-1-4613-0561-3 DOl: 10.1007/978-1-4613-0561-3 1. High temperature superconduCTors. 2. High temperature superconductivity. 3. Superconductors--Chemlstry. 4. Oxygen. 1. Moran-lopez. J. l . ,Jose l.). 1950- II. Schuller. Ivan K. OC811.98.rl54J99 1990 537.6·23--dc20 89-49258 CIP Proceedings of a conference on Oxygen Disorder Effects in High-Tc Superconductors, held April 18-21, 1989, in Trieste, Italy © 1990 Plenum Press, New York Softcover reprint of the hardcover 1st edition 1990 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 papers in this book represent the proceedings for the International Conference on Oxygen Disorder Effects in High~Tc Superconductors, held April 18-21, 1989 at the International Centre for Theoretical Physics, Trieste, Italy. It was recognized very early in the field of ceramic superconductors that oxygen plays a crucial role as far as the physical properties of these ma terials are concerned. The preparation requires special heating and cooling cycles which allow proper uptake of oxygen, relationships were found between the oxygen concentration and the superconducting transition temperature in many of the compounds and quite recently it was recognized that many (if not all) of the compounds present oxygen ordering in the intercalating planes. Moreover, it seems that the presence of superconductivity is strongly correlated with the presence of orthorhombic phases although several groups have also claimed the presence of superconductivity in tetragonal phases. Whether oxygen ordering plays or not a crucial role for the superconductivity remains to be seen. However it is clear that the ordering of oxygens and their thermodynamic properties is an interesting subject on its own right. All these reasons led us to organize a Conference on Oxygen Disorder Effects in High-Tc Superconductors in attempt to identify unsolved problems and to have an open discussion of the presently known facts. The general consensus of the meeting was that oxygen is vital in the high Tc superconductor materials. From the conference the following points can be marked: 1. The lattice structure as well as the ordering of oxygen in the high Tc superconductors is now well established. 2. The theoretical understanding of the oxygen ordering and of the phases is also good on the basis of phenomenological models. 3. The electronic structure of stoichiometric compounds is very well estab lished from band structure calculations. 4. Tight-binding models for the local density of states of partially ordered systems have been performed and seem appropriate for these systems. 5. Substitution studies show interesting trends but the full interpretation is still unclear. v vi PREFACE 6. Much experimental data on the magnetic properties of rare earth ions in the high Tc materials as a function of oxygen content were presented. The interpretation of most of them is lacking. 7. Raman scattering experiments for various oxygen concentrations were presented and models for the oxygen vibrations were discussed. The conference counted with the participation of researchers, theorist and experimentalists involved in issues related to the main team of the confer ence. Spon.sorship was received from the International Centre for Theoretical Physics, the Organization of American States, the Mexican National Council of Science and Technology, to help defray travel and subsistence cost of many of the participants. We thank the participants for all the efforts they have put on the presentations and the manuscripts and to Professor Mario Tosi for his support in the organization of the meeting. J.L. Moran-Lopez San Luis PotosI, S.L.P., Mexico LK. Schuller San Diego, California August, 1989 CONTENTS PHASE DIAGRAMS: EXPERIMENTAL AND THEORETICAL STUDIES Powder Neutron Diffraction Study of the Structural Phase Diagram of the Bal_",K",.Bi03 System........................... 1 SoY. Pei, J.D. Jorgensen, D.G. Hinks, B.D. Dabrowski, D.R. Richards, A.W. Mitchell, S.K. Sinha, D. Vaknin, J.M. Newsam, and A.J. Jacobson Electron Microscopic Studies of Oxygen Ordering Phenomena in YB~CU307_/j .. o. 9 00 •••• 0 0 0 •••• 0 0 0 0 0 0 0 ••••••• 0 00............. S. Amelinda, G. van Tenderloo, and J. van Landuyt Local Atomic Displacements in High Tc Oxydes Studied by Pulsed Neutron Scattering.................................. 47 T. Egami, B.H. Toby, W. Dmowski, J.D. Jorgensen, and D.G. Hinks Oxygen Stoichiometry and Superconductivity in Ceramics 55 0000........ Y. Bruynseraede, J. Vanacken, Bo Wuyts, Jo-P. Locquet, and I.Ko Schuller Oxygen Ordering in YBA2 CU3 06+6: A Phase Diagram Calculation ......... 63 0 ••••••••• 0 0 0 • • • • • • • • • • • • J.M. Sanchez and J.L. Moran-Lopez States of Oxygen Ordering in YB~CU30z 75 D. de Fontaine ELECTRONIC STRUCTURE Effects of COF-relation and Disorder on the Electronic Properties of RB~Cu306+'" .................. 89 0.0 •• 0 0 ••• 0 0.00.. A. Latge, E.V. Anda, and J.L. Moran-Lopez vii viii CONTENTS Tight-binding Investigation of the Electronic Properties of Ordered and Disordered Defects in the YBaCuO system ............................................. 101 Ph. Lambin Electronic Structure of the Cuprate and Bismuthate Superconductors.............................................. 117 L.F. Mattheiss MAGNETIC PROPERTIES Flux Pinning and Thermally Activated Flux Flow Behavior in Single Crystalline YB~CU307 and Bi2Sr2CaCu20S ........ 127 J. van den Berg, P.H. Kes, P.Koorevaar, G.J. Nieuwenhuys, J.A. Mydosh, M.J.V. Menken, and A.A. Menovsky Superconducting Phase Diagram of High Tc Ceramic................ 141 F. de la Cruz, L. Civale, and H. Safar Magnetic Ordering of Rare Earth (R) Ions in RB~ CU3 07- 6 Compounds (R=Nd, Sm, Dy, Er; O~ 0 ~1) ................... 151 B.W. Lee, J.M. Ferreira, S.Ghamaty, K.N. Yang, and M.B. Maple Spin and Hole Dynamics in Doped Anisotropic Heisenberg Antiferromagnets ............................................. 163 M. Lagos Spin-hole Model with Magnetic Vortex-antivortex Pairing Mechanism for Doped L~CU04 .............................. 169 A. Robledo and C. Varea CHEMICAL SUBSTITUTIONS Study of Superconducting ANsD Parent Phases by Chemical Modifications ................................................. 181 P. Barboux, J .M. Tarascon, M.K. Kelly, P.F. Miceli, L.H. Greene, D.E. Aspnes, G.W. Hull, M. Giroud, Y Lepage and W.R. McKinnon Experimental Study of High Temperature Superconductors through Substitutions ................................................. 189 C.L. Chien, G. Xiao, and M.Z. Cieplak Theoretical Study of Oxygen Disorder Effects in YBa2(Cul_",M",)g07_Y (M=AI, Co, Fe, Ga) 201 G. Baumgiirtel and K.H. Bennemann CONTENTS ix PHONONS Characterization of Twins and Twin Domains of YBaCuO Single Crystals by Micro-Raman Scattering ......................... 211 P. Knoll SUMMARY Oxygen Disorder Effects in High Tc Superconductors, 1989 221 K.H. Bennemann Index............................................................... 227 POWDER NEUTRON DIFFRACTION STUDY OF THE STRUcruRAL PHASE DIAGRAM OF THE Bal_xKxBi03 SYSTEM Shiyou Pei, J. D. Jorgensen, D. G. Hinks, B. Dabrowski D. R. Richards and A. W. Mitchell Materials Science Division Argonne National Laboratory Argonne,IL 60439 S. K. Sinha, D. Vaknin, J. M. Newsam and A. J. Jacobson Exxon Research and Engineering Company Clinton Township, Route 22 East Annandale, NJ 08801 In this article we present a brief report of recent work carried out to elucidate the phase diagram of the Bal_xKxBi03 system. A full account of this investigation will be published shortly'! The recently discovered "high-Tc" superconductor Bal_xKxBi03 is unique in the sense that unlike the other high-Tc superconductors, it does not contain Cu02 planes and is cubic rather than layered in structure. It does, however, exhibit a series of structural phase transitions as a function of both K concentration x and temperature. Superconductivity occurs only in a cubic phase and disappears abruptly at x ..:::; 0.4 where the behavior apparently becomes non-metallic.2 Few details have been available hitherto of the structural phases found as x is decreased, and some of the reported results are not consistent with each other. The present measurements were carried out on the H4S triple axis spectrometer at Brookhaven's High Flux Reactor and on the Special Environment Powder Diffractometer (SEPD) at Argonne's Intense Pulsed Neutron Source. The samples were prepared using the two-step synthesis method.3,4,5 Pellets were made of stoichiometric mixtures of powder of Bi203, BaO and K02, fired in flowing nitrogen at a temperature below 725°C and then annealed in 2 S.Y. PEl ET AL. in flowing oxygen at a lower temperature. This procedure was repeated several times with intermediate grinding. The first batch of samples, with nominal compositions x = 0, 0.1, 0.2, 0.3 and 0.4 were run at Brookhaven. They were not completely single-phase and showed some oxygen deficiency, and the powder diffraction results were used primarily to obtain the structures of the different phases rather than to characterize the details of the phase diagram. A later synthesis produced more homogeneous samples of nominal compositions x = 0, 0.1,0.2,0.25,0.3,0.35,0.4,0.425,0.5 and 0.6, which were studied at Argonne and used to refine the details of the structure and obtain the structural phase diagram. In both sets of experiments, the neutron powder diffraction (NPD) data were analyzed by full matrix Rietveld refinement.6 ' The structures which occur in the Bal_xKxBi03 system can be viewed as distortions of the basic cubic perovskite structure. The fundamental distortions are rotations of nominally rigid Bi06 octahedra or breathing distortions involving oxygen atom displacements towards or away from the--Bi atoms, thus making the Bi atoms inequivalent. These distortions can occur singly or in combination to produce the various possible distorted perovskite structures. Glazer7,8 has characterized the systematics of distortions produced by octahedral rotations about various axes, which serve to double the cubic perovskite unit cell. This COUNTS '250.0 Space Group: lbmm A. = 2.3701A 5550.0 3700.0 1850.0 0.0 I I I I II II I r II II 6.0 22.2 38.4 54.6 70.8 87.0 103.2 11'.4 Two Thet.a Figure l(a) Neutron powder diffraction data taken on BaO.9Ko.IBi03 at room temperature on the crystal diffractometer at Brookhaven, together with the Rietveld-refined fit. The lower curve represents the difference pattern between the measured and fitted profiles.
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