COLOSSAL MAGNETORESISTANCE EFFECT OF LANTHANUM STRONTIUM MANGANESE OXIDE CERAMICS DOPED WITH TIN, BISMUTH AND INDIUM ON MANGANESE SITES

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1 COLOSSAL MAGNETORESISTANCE EFFECT OF LANTHANUM STRONTIUM MANGANESE OXIDE CERAMICS DOPED WITH TIN, BISMUTH AND INDIUM ON MANGANESE SITES By RAMADAN EBRAHIM ALI SHAIBOUB Thesis Submitted to the School of Graduate Studies,, in Fulfillment of the Requirements for the Degree of Master of Science April 2004 i

2 DEDICATION To my parents, for their care, patience and teaching To my family and Dear wife For her support, understanding and concern My Sons, brothers and sisters Fellow friends, course mates and as a whole ii

3 Abstract of thesis presented to the Senate of in fulfilment of the requirement for the degree of Master of Science COLOSSAL MAGNETORESISTANCE EFFECT OF LANTHANUM STRONTIUM MANGANESE OXIDE CERAMICS DOPED WITH TIN, BISMUTH AND INDIUM ON MANGANESE SITES By RAMADAN EBRAHIM ALI SHAIBOUB April 2004 Chairman: Professor Abdul Halim Shaari, Ph.D. Faculty: Science and Environmental Studies Since the discovery of colossal magnetoresistance (CMR) effect in the perovskite type of manganites, much research works have been carried out to improve the CMR value by introducing different type of dopant in the system. In this work the effect of rare earth elements Tin (Sn), Bismuth (Bi) and Indium (In) substitution in the La 0.67 Sr 0.33 MnO 3 system on Mn site had been investigated. The (LSMSnO), (LSMBiO) and (LSMInO), with x=0.00 to x=0.40 ceramic samples were prepared by solid-state reaction technique. The temperature dependence of the magnetic susceptibility, the electrical transport, XRD spectrum of all samples, microstructure and magnetoresistance measurements in the three systems have been studied systematically. With increasing Sn, Bi and In concentration, Tc shifted toward lower temperature, but the lattice constants remain almost unchanged. For higher doping, the spin glass-like state is observed and the system behaves like insulator. These results strongly suggest that the dopant Sn, Bi and In ions weaken the double iii

4 exchange interaction. The X-ray diffraction patterns indicate that La 0.67 Sr 0.33 MnO 3 compounds are in single phase with rhombohedra structure. From the ac magnetic susceptibility χ measurements, transitions from paramagnetic (PM) to ferromagnetic (FM) state are observed, indicating the loss of ferromagnetical ordering and consequently weaken the double exchange (DE) mechanism. When the competition between ferromagnetism and antiferromagnetism is strong, spin glass behavior is usually found with freezing temperature for all systems. From the resistance measurements, the metal-to-insulator (M-I) transition occurs at a T mi. The (M-I) transitions temperature, T mi shifts towards lower temperature as the Sn, Bi and In content increases and the resistance increases accordingly. The grain size for the dopant concentration of Tin, Bismuth and Indium doped with LSMO system, shows that the grain size essentially decreases with the increase of the dopant amount but remains almost constant size at x>0.12, which indicates that the dissolving amount of the dopant in LSMO may be less when x<0.12. MR values of the three systems are very temperature dependent. The samples exhibit the maximum CMR value at certain temperature. For undoped sample, the maximum MR value observed is 11 %. Among these three doped systems, the highest value of CMR with dopant is observed for LSMBiO system with x=0.06 with the value of 45 % at 250 K. The colossal magnetoresistive effect of the three systems, appear between 100 K and 250 K. iv

5 Abstrak tesis yang dikemukakan kepada Senat sebagai memenuhi keperluan ijazah Master Sains KESAN MAGNETORINTANGAN RAKSAKSA BAGI SERAMIK LANTHANUM STRONTIUM MANGANIS OKSIDA DIDOP DENGAN TIMAH, BISMUTH DAN INDIUM PADA TAPAK MANGANIS Oleh RAMADAN EBRAHIM ALI SHAIBOUB April 2004 Pengerusi: Fakulti: Profesor Abdul Halim Shaari, Ph.D. Sains dan Pengajian Alam Sekitar Sejak penemuan kesan magnetorintangan Raksaksa (MRR) dalam bahan manganit jenis perovskite, banyak kajian telah dijalankan untuk memperbaiki nilai MRR dengan menggunakan jenis bahan campuran yang berlainan pada sistem. Dalam kajian ini, kesan dari unsur nadir-bumi seperti penggantian Timah (Sn), Bismuth (Bi) dan Indium (In) dalam sistem La 0.67 Sr 0.33 MnO 3 pada tapak Manganis telah dikaji. Sampel seramik dari jenis LSMSnO, LSMBiO dan LSMInO dengan x=0.00 sehingga x=0.40 disediakan melalui teknik tindakbalas keadaan pepejal. Persandaran terhadap oleh suhu kerentanan magnet, pengaliran elektrik, spektrum XRD untuk semua sampel mikrostruktur dan pengukuran magnetorintangan dalam ketiga-tiga sistem telah dikaji secara sistematik. Dengan penambahan kandungan Sn, Bi dan In, Tc beralih ke suhu lebih rendah, tetapi pemalar kekisi hampir tidak berubah. Untuk pendopan yang lebih tinggi, keadaan menyerupai spin-kaca telah ditemui dan sistem berkelakuan seperti penebat. Hasil ini mengukuhkan cadangan bahawa bahan dopan v

6 Sn, Bi dan In ion melemahkan interaksi pertukaran ganda dua. Corak belauan sinaranx menunjukkan bahawa bahan La 0.67 Sr 0.33 MnO 3 adalah dalam keadaan satu fasa dengan struktur rhombohedron. Dari pengukuran kerentanan magnet AC,χ, menunjukkan satu peralihan dari keadaan paramagnet (PM) ke feromagnet (FM) kelihatan, yag menunjukkan kehilangan tertib feromagnet dan seterusnya melemahkan mekanisma pertukaran ganda dua (DE). Apabila pertandingan antara feromagnet dengan antiferomagnet adalah kuat, kelakuan spin kaca akan dijumpai dengan suhu beku untuk semua sistem. Dari ukuran rintangan, peralihan logam ke penebat (M-I) wujud pada T mi. Suhu peralihan (M-I), T mi beralih ke suhu lebih rendah bila kandungan Sn, Bi dan In bertambah dan rintangan turut bertambah. Saiz butiran untuk kandungan dopan bagi timah, Bismuth dan Indium untuk LSMO, menurun apabila amaun dopan bertambah tetapi hampir tidak berubah pada x>0.12, ini menunjukkan amoun resapan dopan dalam LSMO mungkin kurang apabila x<0.12. Nilai MR untuk ketiga-tiga sistem adalah sangat bergantung kepada suhu. Sampel menunjukkan nilai MRR maksimum dalam suhu tertentu. Untuk sampel tulen, nilai maksimum MRR yang didapati adalah 11%. Antara ketiga-tiga sistem ini, nilai MRR yang paling tinggi adalah untuk sistem LSMBiO dengan x=0.06 iaitu 45% pada 250K. Magnetorintangan Raksaksa untuk ketiga-tiga sistem, wujud antara 100K dan 250K. vi

7 ACKNOWLEDGEMENTS Firstly, I would like to thank my supervisor Professor Dr. Abdul Halim B. Shaari for inviting me into his group and for making it possible for this thesis to appear. I greatly appreciate your constant encouragement and your belief in me. Your scientific insight helped me through a number of key points in my research and for your patient answers to all my questions. It is my pleasure to acknowledge my co-supervisors A.W.Zaidan, Y.B.Noorhana, whose comments and suggestions were essential throughout this project. I'm grateful to my indebtedness to my country for the financial support through Fellowship by the People s Bureau of the Great Socialist People s Libyan Arab Jamahiriya. I owe particular thanks to Mr. Razak B. Harun for technical favors, Mrs. Noriza for her kind help, staffs in the Physics Department and staffs from Electron Microscope Unit, Institute of Bioscience for their significant contribution. Thanks are also given to my working colleagues, especially for Dr. Imad Hamadneh, Dr. Lim Kean Pah, Mr. Abdullah Chik, Mr. Kabashi Kathir, Ms. Zohra Gebrel, Ms. Sharmiwati B. Mohamed, Mr. Mustafa Daihom, Mr. Ali Agail, Mr. Azman Awang, Ms. Iftetan, Ms. Hazar, Mr. Teh Jia Yew, Mr. Walter Charles for their assistance during the course of the project in using and handling of all equipments in the laboratory and also on the X-ray diffraction (XRD) analysis. My most sincere gratitude also goes to my parents, my wife Mrs. Fathia Yakhlaf, my daughters; Amel, Eyman, Assma, my Son; Mohamed, my brothers, sisters and vii

8 friends. During my stay in Malaysia, I found a lot of new friends, and I hope the friendship will continue. To all of them-the old, and the new-thanks for your time supports and understanding. Finally, I acknowledge with gratitude the grant from Ministry of Science, Technology, and Environment, Malaysia through IRPA vote: [ ] under which this work was completed. viii

9 I certify that an Examination Committee met on 09 / 4 / 2004 to conduct the final examination of Ramadan Ebrahim Ali Shaiboub on his Master of Science thesis entitled Colossal Magnetoresistance Effect of Lanthanum Strontium Manganese Oxide Ceramics Doped with Tin, Bismuth and Indium on Manganese Sites in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulation The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows: Jumiah Hassan, Ph.D. Faculty of Science and Environmental Studies (Chairman) Sidek Hj Ab. Aziz, Ph.D. Associate Professor Faculty of Science and Environmental Studies (Member) Hishamuddin Zainuddin, Ph.D. Associate Professor Faculty of Science and Environmental Studies (Member) Ibrahim Abu Talib, Ph.D. Professor Universiti Kebangsaan Malaysia (Independent Examiner) GULAM RUSUL RAHMAT ALI, Ph.D. Professor/Deputy Dean School of Graduate Studies Date: ix

10 This thesis submitted to the Senate of and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of the Supervisory Committee are as follows: Abdul Halim Bin Shaari, Ph.D. Professor Faculty of Science and Environmental Studies (Chairman) A.W.Zaidan, Ph.D. Faculty of Science and Environmental Studies (Member) Y.B.Noorhana, Ph.D. Faculty of Science and Environmental Studies (Member) AINI IDERIS, Ph.D. Professor/Dean School of Graduate Studies Date: x

11 DECLARATION I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions. RAMADAN EBRAHIM ALI SHAIBOUB Date: xi

12 TABLE OF CONTENTS Page DEDICATION ABSTRACT ABSTRAK ACKNOWLEDGEMENTS APPROVAL DECLARATION LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS/NOTATIONS/GLOSSARY OF TERMS ii iii v vii ix xi xv xvi xxii CHAPTER I INTRODUCTION 1 Magnetoresistance 2 Application of Magnetoresistance 2 Colossal Magnetoresistance in Mn pervoskite 3 Other CMR materials 4 Basis of Work 6 Objectives of the Study 6 II LITERATURE REVIEW 8 Early Studies of Magnetic and Magnetoresistance Properties 9 Doping Effect on Mn site 12 La 0.67 Sr 0.33 Mn 1-x Zr x O 3 System (LSMZrO) 12 La 0.67 Sr 0.33 Mn 1-x Cr x O 3 System (LSMCrO) 13 La 0.67 Sr 0.33 Mn 1-x Ni x O 3 System (LSMNiO) 15 La 0.67 Sr 0.33 Mn 1-x Fe x O 3 System (LSMFeO) 16 La 0.67 Sr 0.33 MnO 3 System (LSMO) 17 Properties of Manganites Perovskite Oxides 22 Structural Properties of Manganites 23 Crystallographic properties of doped manganites 24 Low-Field Magnetoresistance in Perovskite Manganites 25 III THEORY 28 Theory of Manganites 28 Fundamentals of Magnetism 31 Classes of Magnetic Materials 31 Diamagnetism 32 Paramagnetism 33 Ferromagnetism 35 Ferrimagnetism 38 Antiferromagnetism 39 Magnetic Susceptibility 42 xii

13 Curie temperature and Curie Weiss Law 43 Double exchange 45 Jahn-Teller Distortion 47 Superexchange Model 48 Spin Glass 50 Charge ordering in the rare earth Manganites 51 Types of Magnetoresistance 52 Colossal Magnetoresistance 55 The Colossal Magnetoresistance Effect 57 Colossal Magnetoresistance ratios (CMR %) 58 Mechanisms of Colossal Magnetoresistance 59 Tolerance Factor 61 Resistivity and phase diagram 63 IV METHODOLOGY 65 Sample Preparation 65 Homogenization 65 Evaporation 66 Calcinations 66 Grinding and Sieving of Material 67 Pelletizing 67 Sintering 68 Sample Characterization 70 Phase Transition Temperature Measurement, Tp 71 Curie Temperature and AC Magnetic Susceptibility Measurement. 72 X-ray Diffraction Analysis (XRD) 73 Magnetoresistance Measurement (MR) 75 Microstructure Analysis 77 V RESULTS AND DISCUSSIONS 79 LSMSnO System 79 A.C. Susceptibility, χ and Curie temperature, Tc 79 Effect of Field Intensity 85 Resistance and phase transition temperature, Tp 87 Magnetic and Electrical phase diagram 91 XRD Patterns and Lattice Parameters 92 Microstructure Properties 94 Energy Dispersive X-ray Analysis (EDXA) 97 Magnetoresistance 98 LSMBiO System 104 A.C. Susceptibility, χ and Curie temperature, Tc 104 Effect of Field Intensity 107 Resistance and phase transition temperature, Tp 111 Magnetic and Electrical phase diagram 113 XRD Patterns and Lattice Parameters 114 Microstructure Properties 116 Energy Dispersive X-ray Analysis (EDXA) 119 Magnetoresistance 120 xiii

14 LSMInO System 127 A.C. Susceptibility, χ and Curie temperature, Tc 127 Effect of Field Intensity 130 Resistance and phase transition temperature, Tp 134 Magnetic and Electrical phase diagram 136 XRD Patterns and Lattice Parameters 137 Microstructure Properties 139 Energy Dispersive X-ray Analysis (EDXA) 142 Magnetoresistance 143 Observation of Highest MR Value 149 LSMSnO system 150 LSMBiO system 150 LSMInO system 151 Comparison among the Three Systems 155 Curie Temperature Tc 155 Phase Transition Temperature, Tp 156 XRD Patterns and Lattice Parameters 158 Microstructure 158 Magnetoresistance 159 VI CONCLUSIONS AND SUGGESTIONS 161 Conclusions 161 Suggestions 165 REFERENCES 167 APPENDICES 175 BIODATA OF THE AUTHOR 201 xiv