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UNIVERSITI PUTRA MALAYSIA
ELUCIDATION OF THE PARALLEL EVOLUTIONS
OF MICROSTRUCTURE AND MAGNETIC PROPERTIES
AND THEIR RELATIONSHIP IN NICKEL-ZINC FERRITE
IDZA RIATI BINTI IBRAHIM
FS 2011 59
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ELUCIDATION OF THE PARALLEL EVOLUTIONS
OF MICROSTRUCTURE AND MAGNETIC PROPERTIES
AND THEIR RELATIONSHIP IN NICKEL-ZINC FERRITE
IDZA RIATI BINTI IBRAHIM
MASTER OF SCIENCE
UNIVERSITI PUTRA MALAYSIA
2011
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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfillment of the requirement for the degree of Master of Science
ELUCIDATION OF THE PARALLEL EVOLUTIONS OF
MICROSTRUCTURE AND MAGNETIC PROPERTIES AND THEIR
RELATIONSHIP IN NICKEL-ZINC FERRITE
By
IDZA RIATI BINTI IBRAHIM
December 2011
Chairman: Assoc. Prof. Mansor Hashim, PhD
Faculty: Faculty of Science
In this research work, parallel evolving morphology and magnetic properties in
nickel zinc ferrite with composition Ni0.3Zn0.7Fe2O4 were studied. For several past
decades, studies of the relationship between morphological properties and magnetic
properties of ferrites have been focusing only on the product of the final sintering
temperature, largely neglecting the parallel evolutions of morphological and
magnetic properties and their relationships at various lower sintering temperatures.
Hence, here, in this thesis we report some research findings on the parallel evolutions
of such morphological properties and magnetic properties; we attempt to elucidate
their relationships. Nickel zinc ferrite was prepared via High-energy ball milling in a
hardened steel vial for 2 hours using a SPEX8000D mill. The toroidal samples went
through two different sintering routes which were multi-sample sintering and single-
sample sintering. In the multi-sample sintering, the samples were sintered from
600oC to 1400
oC using 100
oC increments with any one sample being subjected to
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only one sintering temperature. Nevertheless, for the single-sample sintering, the
same sample was subjected to repeat sintering from 600oC to 1400
oC with 100
oC
increments. The completion of the solid state reaction was confirmed by X-ray
diffraction (XRD) using a Philips X-ray diffractometer. The evolution of
microstructural properties was studied using an FEI Nova NanoSEM 50 series. The
magnetic studies were carried out by using a Linkjoin Technology MATS-2010SD
B-H Hysteresisgraph and an Agilent Model HP4291B Impedance/Material Analyzer.
The XRD patterns showed an improvement of crystallinity with increasing sintering
temperature. Ni-Zn ferrite peaks were the only observed peaks for samples sintered
at 800oC upwards for both sintering routes. SEM micrographs showed larger grain
size as the sintering temperature increased, consequently increasing the multi-domain
grains. The density values for the samples in both sintering routes proportionally
increased with sintering temperature up to 1300oC but dropped at 1400
oC showing an
increased presence of pores. The real permeability, µ’, and loss factor, µ”, increased
generally with increasing sintering temperature but dropped at the 1400oC sintering
temperature; the drop is attributed to increased porosity in grains. An integrated
analysis of phase, microstructural, hysteresis and permeability data would point to
the existence of three distinct shape-differentiated and sintering-temperature
dependent groups of B-H hysteresis loops which belong to samples with weak,
moderate and strong magnetism. One interesting result can be deduced from the
phase, grain-size distribution and B-H curve data: the first appearance of strong
ferromagnetic behaviour is indicated by the first occurrence of a strikingly erect
sigmoid-shape B-H curve. That well-defined shape was observable only when
sufficient single-phase purity and crystallinity and a sufficiently high volume fraction
of grains with diameters >0.25 µm were attained. The B-H hysteresis shape evolution
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was thus strongly influenced by the parallel evolution of the microstructure which
developed from being predominantly single-domain to predominantly multi-domain.
A scrutiny of the permeability parameters, µ’ and µ”, shows that these also seem to
belong to the same three sintering-dependent groups mentioned above, consistent
with the parameters’ known dependence on the magnetization and the microstructure.
The measured Curie temperature remained unaffected by the above evolutions since
the exchange strength, on which the Curie temperature depends, is dependent only on
the crystal structure and compositional stoichiometry. However the measured
resistivity was found to decrease with increasing sintering temperature due to the
combined effect of increased grain size and Fe2+
ions due to increasing zinc loss.
Both single-sample and multi-sample sintering would led to highly similar results
and conclusions.
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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk Ijazah Master Sains
PENJELASAN EVOLUSI SELARI SIFAT-SIFAT MIKROSTUKTUR,
MAGNET DAN HUBUNGAN KEDUA-DUANYA DALAM FERIT NIKEL
ZINK
Oleh
IDZA RIATI BINTI IBRAHIM
Disember 2011
Pengerusi: Prof. Madya Mansor Hashim, PhD
Fakulti: Fakuti Sains
Dalam kerja penyelidikan ini, kajian ke atas evolusi sifat-sifat mikrostruktur dan
magnet dalam ferit nikel zink berkomposisi Ni0.3Zn0.7Fe2O4 telah dijalankan secara
selari. Untuk beberapa dekad yang lalu, kajian ke atas hubungan sifat-sifat
mikrostruktur dan sifat-sifat magnet hanya tertumpu kepada produk pada suhu
pensinteran akhir dengan mengabaikan evolusi sifat-sifat mikrostruktur dan magnet
yang selari pada pelbagai suhu pensinteran yang rendah. Oleh itu, kami melaporkan
beberapa penemuan penyelidikan mengenai sifat-sifat magnet yang mempunyai sifat-
sifat mikrostruktur tersebut. Ferit nikel zink telah disediakan dengan menggunakan
pengisar bebola berkuasa tinggi selama 2 jam menggunakan pengisar SPEX8000D di
dalam bekas keluli dan bebola terkuat. Sampel-sampel toroid melalui dua proses
pensinteran iaitu pensinteran pelbagai sampel dan pensinteran sampel tunggal.
Dalam pensinteran pelbagai sampel, sampel disinter dari 600oC hingga 1400
oC
dengan kenaikan 100oC dengan menggunakan sampel berlainan bagi setiap suhu.
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Tetapi, dalam pensinteran sampel tunggal pula, hanya satu sampel digunakan dan
dilakukan pensinteran berulang ke atas sampel tersebut dari suhu 600oC hingga
1400oC dengan kenaikan 100
oC. Penyempurnaan tindakbalas keadaan pepejal
diperiksa dengan menggunakan pembelauan sinar-x (XRD) dengan menggunakan
Philips X-ray diffractometer. Evolusi sifat-sifat mikrostruktur dikaji dengan
menggunakan FEI Nova NanoSEM 50 series. Kajian sifat-sifat magnet telah
dijalankan dengan menggunakan B-H Hysteresisgraph Linkjoin Technology model
MATS-2010SD dan Penganalisis Impedan/Bahan model Agilent HP4291B. Corak-
corak pembelauan sinar-x menunjukkan peningkatan kehabluran dengan
meningkatnya suhu pensinteran. Keseluruhan fasa ferit nikel zink mula ditemui pada
suhu pensiteran 800oC untuk kedua-dua proses pensinteran. Mikrograf-mikrograf
mikroskop pengimbas elektron menunjukkan peningkatan saiz butiran dengan
peningkatan suhu pensinteran, dan dengan itu telah meningkatkan juga butiran yang
mempunyai domain berbilang. Nilai-nilai ketumpatan untuk sampel bagi kedua-dua
proses pensinteran meningkat sehingga suhu 1300oC, tetapi menurun pada suhu
1400oC akibat peningkatan liang-liang. Ketelapan dan faktor kehilangan meningkat
dengan peningkatan suhu pensinteran tetapi menurun pada suhu 1400oC disebabkan
oleh peningkatan liang-liang di dalam butiran. Suatu analisis fasa, mikrostruktur,
histerisis dan ketelapan bersepadu akan menunjukkan kepada kewujudan tiga
kumpulan gelung histeresis B-H yang berasaskan bentuk, dengan pergantungan
kepada suhu pensinteran, yang mewakili sampel yang mempunyai kemagnetan
lemah, sederhana dan kuat. Suatu penemuan yang menarik boleh disimpulkan dari
fasa, taburan saiz butiran dan data lengkung B-H: kemunculan pertama sifat
feromagnetik kuat ditunjukkan dengan kemunculan pertama lengkung B-H bentuk
sigmoid yang ketara tegak. Bentuk yang jelas itu hanya mampu dilihat apabila
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ketulenan fasa tunggal dan kehabluran yang mencukupi dan juga apabila terdapat
pecahan saiz butiran melebihi 0.25 µm yang cukup tinggi dicapai. Maka evolusi
bentuk histeresis B-H ternyata kuat dipengaruhi oleh evolusi selari mikrostruktur
yang berkembang daripada sifat domain-tunggal menonjol kepada sifat domain-
berbilang menonjol. Suatu penelitian parameter ketelapan, µ’ dan µ”, menunjukkan
parameter-parameter ini juga tergolong kepada tiga kumpulan yang bergantung
kepada suhu pensinteran seperti di atas, selaras dengan pergantungan biasa
parameter-parameter ini terhadap pemagnetan dan mikrostruktur. Suhu Curie
didapati tidak terkesan oleh evolusi di atas kerana kekuatan tukarganti yang
menentukan suhu Curie hanya bergantung kepada struktur hablur dan komposisi
stoikiometri. Bagaimanapun, kerintangan didapati menurun disebabkan oleh kesan
gabungan pertambahan saiz butir dan bilangan ion Fe2+
daripada peningkatan
kehilangan zink.
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ACKNOWLEDGEMENTS
First praise is to Allah, the Almighty, on whom ultimately we depend for
sustenance and guidance. With His blessing, help and will, we able to make this
work a success.
My sincere appreciation and gratitude goes to my supervisor Associate
Professor Dr. Mansor Hashim for his continuous guidance, advice and support. With
his timely and efficient contribution helped me shape this into its final form and I
express my sincerest appreciation for his assistance in any way that I may have asked.
I would also like to extent my sincere to my co-supervisor, Dr. Khamirul Amin
Matori and also to all my lecturers for their helps throughout this project.
I am highly grateful for the love, care, prayers and support from the most
important persons in my life, my mother, Razilah Othman and my brother,
Idzharudin Ibrahim who made the accomplishment of this project possible. To my
late father, Allahyarham Ibrahim Nor, I know that I have made you proud. Al-fatihah
to my beloved late father. May his soul rest in peace and be placed amongst the
blessed alongside Allah S.W.T.
To my colleagues in the Magnetics and Nanostructure Evolution Group
(MNEG), Rodziah, Ismayadi, Shamsul, Ghazal, Nora, Hapishah, Faz, Masni, Mehran
and not to forget Samaila and Tania. I appreciate the discussions, ideas, memorable
interactions and time spent throughout this research. To my fellow friends during my
postgraduate study, Ana, Noni, Kun, Ibik, Fifi, Ain Shaaidi, Ain Rusly, Dila, Lin and
many others, I say thanks for everything. Lastly, I would also like to express my
gratitude to all Faculty of Science staff and Advanced Material and Nanotechnology
Lab staff, Pn. Norhaslinda, Pn. Noriza, Pn. Khamsiah, En. Kadri, and many others
for their great helps and contributions.
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I certify that a Thesis Examination Committee has met on 20 December 2011 to
conduct the final examination of Idza Riati binti Ibrahim on her thesis entitled
“Elucidation of the Parallel Evolutions of Microstructure and Magnetic Properties and Their Relationship in Nickel-Zinc Ferrite” in accordance with the Universities
and University Colleges Act 1971 and the Constitution of the Universiti Putra Malaysia [P.U.(A) 106] 15 March 1998. The committee recommends that the student
be awarded the Master of Science.
Member of the Thesis Examination Committee were as follows:
Chen Soo Kien, PhD
Senior Lecture
Faculty of Science
Universiti Putra Malaysia
(Chairman)
Wan Mahmood Mat Yunus, PhD
Professor
Faculty of Science Universiti Putra Malaysia
(Internal Examiner)
Jumiah Hassan, PhD
Associate Professor
Faculty of Science Universiti Putra Malaysia
(Internal Examiner)
Ahmad Kamal Yahya, PhD
Professor
Faculty of Applied Sciences
Universiti Teknologi Mara
(External Examiner)
_________________________
SEOW HENG FONG, PhD
Professor and Deputy Dean
School of Graduate Studies Universiti Putra Malaysia
Date:
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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfillment of the requirement for the degree of Master of Science. The
members of the Supervisory Committee were as follows:
Mansor Hashim, PhD
Associate Professor
Faculty of Science
Universiti Putra Malaysia
(Chairman)
Khamirul Amin Matori, PhD
Senior Lecturer
Faculty of Science
Universiti Putra Malaysia
(Member)
______________________________
BUJANG BIN KIM HUAT, PhD
Professor and Dean
School of Graduate Studies Universiti Putra Malaysia
Date:
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DECLARATION
I declare that this thesis is my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously
and is not concurrently submitted for any other degree at Universiti Putra Malaysia or other institutions.
____________________________
IDZA RIATI BINTI IBRAHIM
Date: 20 December 2011
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TABLE OF CONTENTS
Page
ABSTRACT i ABSTRAK iv
ACKNOWLEDGEMENTS vii
APPROVAL viii
DECLARATION x
LIST OF TABLES xiii
LIST OF FIGURES xiv
LIST OF SYMBOLS AND ABBREVIATIONS xviii
CHAPTER
1 INTRODUCTION
1.1 Background of the study 1 1.2 Ferrite materials 2
1.3 Historical Overview 3 1.4 Problem Statement 5
1.5 Objectives 6
2 LITERATURE REVIEW
2.1 Introduction 7
2.2 Synthesize methods of spinel ferrites 7
2.3 Chemical aspects of spinel ferrite 10
2.4 Influence of microstructure on magnetic properties 11
3 THEORY
3.1 Introduction 16
3.2 Magnetism in Ferrite 16
3.2.1 Fundamentals of Magnetism 16
3.2.2 Crystal Structure of Spinel Ferrites 19
3.2.3 Site Preference of the Ions 20
3.2.4 Ferrimagnetism in spinel 22
3.2.5 Domain Magnetism 25
3.3 Magnetic properties of ferrite 26 3.3.1 Intrinsic properties 27
3.3.1.1 Saturation Magnetization 27 3.3.1.2 Curie temperature 27
3.3.1.3 Magnetic Anisotropy 28 3.3.1.4 Magnetostriction 30
3.3.2 Extrinsic properties 31 3.3.2.1 Permeability 31
3.3.2.2 Hysteresis loop 32
3.2.2.3 Magnetic Losses 34
3.2.2.4 Resistivity 36
3.4 Microstructural dependence on magnetic properties of ferrite 36
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3.5 Mechanism of Mechanical Alloying 39
4 METHODOLOGY
4.1 Introduction 42
4.2 Fabrications of ferrites 42 4.3 Experimental Procedure 43
4.3.1 Sample preparation 43
4.3.1.1 Chemical formula of desired material 45
4.3.1.2 Weighing of the constituent powders 45
4.3.1.3 Mixing 45
4.3.1.4 High-energy ball milling 45
4.3.1.5 Addition of binder and lubricant 46
4.3.1.6 Moulding 47
4.3.1.7 Sintering 48
4.3.2 Sample measurement and characterization 50
4.3.2.1 Microstructure-related analysis 52
4.3.2.2 Magnetic properties 56
4.4 Errors of measurements 60
5 RESULTS AND DISCUSSION
5.1 Introduction 61 5.2 Microstructure-related analysis 61
5.2.1 Particle size analysis 61 5.2.2 Phase analysis 62
5.2.3 Microstructural properties 68 5.2.3.1 Multi-sample sintering 69
5.2.3.2 Single-sample sintering 74
5.2.3.3 Grain size distribution 79
5.3 Magnetic properties 83
5.3.1 B-H Hysteresis loop 83
5.3.2 Complex permeability 90
5.3.3 Curie temperature 96
5.3.4 Resistivity 99
5.4 Summary 101
6 CONCLUSIONS AND SUGGESTIONS
6.1 Conclusions 104
6.2 Suggestions 105
BIBLIOGRAPHY 106
APPENDICES 111 BIODATA OF STUDENT 115
LIST OF PUBLICATIONS 116
