Producing Calcium Cuprum Mangan Oxide (CaCu3Mn4O12) Via Wet And Dry Chemistry Techniques.

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PRODUCING CALCIUM CUPRUM MANGAN OXIDE

(CaCu

Mn

O

) VIA WET AND DRY CHEMISTRY

TECHNIQUES

NURUL HIDAYAH BINTI ISMAIL

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UNIVERSITI TEKNIKAL MALAYSIA MELAKA

PRODUCING CALCIUM CUPRUM MANGAN OXIDE (CaCu3Mn4O12) VIA WET AND DRY CHEMISTRY

TECHNIQUES

This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Engineering Materials) with Honours.

NURUL HIDAYAH BINTI ISMAIL

FACULTY OF MANUFACTURING ENGINEERING 2009

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SULIT

TERHAD

TIDAK TERHAD

(Mengandungi makl umat yang berdarj ah keselamat an at au kepent ingan Mal aysia yang t ermakt ub di dalam AKTA RAHSIA RASMI 1972)

(Mengandungi makl umat TERHAD yang t el ah dit ent ukan oleh organisasi/ badan di mana penyelidikan dij alankan)

** Jika Laporan PSM ini SULIT at au TERHAD, sil a l ampirkan surat daripada pihak berkuasa/ organisasi berkenaan dengan menyat akan sekal i sebab dan t empoh l aporan PSM ini perl u dikel askan sebagai SULIT at au TERHAD.

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: PRODUCING CALCIUM CUPRUM MANGAN OXIDE (CaCu3Mn4O1 2) VIA WET &

DRY CHEMISTRY TECHNIQUES

SESI PENGAJIAN: 2008/ 2009 Semest er 2 Saya

mengaku membenarkan Laporan PSM ini disimpan di Perpust akaan Universit i Teknikal Malaysia Mel aka (UTeM) dengan syarat -syarat kegunaan sepert i berikut : 1. Laporan PSM adalah hak milik Universit i Teknikal Mal aysia Melaka dan penulis. 2. Perpust akaan Universit i Teknikal Mal aysia Melaka dibenarkan membuat sal inan

unt uk t uj uan pengaj ian sahaj a dengan izin penulis.

3. Perpust akaan dibenarkan membuat sal inan l aporan PSM ini sebagai bahan pert ukaran ant ara inst it usi pengaj ian t inggi.

4. **Sil a t andakan (√)

NURUL HIDAYAH BINTI ISMAIL

√

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Alamat Tet ap:

Lot 313, Kg Jej ul ok Banggu, 16150 Kot a Bharu,

Kelant an.

Tarikh: _______________________

(DR MOHD WARIKH B ABD RASHID) Cop Rasmi:

Tarikh: _______________________ 22 MEI 2009 22 MEI 2009

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DECLARATION

I hereby, declared this report entitled “Producing Calcium Cuprum Mangan Oxide (CaCu3Mn4O12) via Wet and Dry Chemistry Techniques” is the results of my own

research as cited in references.

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APPROVAL

This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a partial fulfillment of the requirements for the degree of Bachelor of Manufacturing Engineering (Engineering Materials) with Honours. The member of the supervisory committee is as follow:

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ABSTRACT

In this project, the preparation of CaCu3Mn4O12 is carried out via wet-chemistry and

solid state reaction methods so that at the end of this study, the differences in the characteristic of the samples produced can be clarified. In addition, in solid state reaction method, the CaCu3Mn4O12 preparation is done by varying the time used for calcination

process in order to investigate the effect of varying that parameter on the characteristics of the product. In order to achieve the objectives of the project, the study is divided into two tasks; preparation of the CaCu3Mn4O12 samples by using sol-gel and solid state

reaction method and material testing on the sample produced. In sample preparation, both methods involves the same processes such as precursor preparation; mixing, stirring, drying in sol-gel method while in solid state reaction, it involves mixing and ball milling, followed by calcination, forming and sintering process. For the second task that is for sample testing, the identification of phase formation and microstructural analysis are characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) respectively, while the characterization of electrical properties is done by using impedance analyzer. The study shows that the formation of CaCu3Mn4O12

phase in x-ray diffraction pattern occurs at 600°C in sol-gel sample and at 800°C in solid state reaction sample. SEM micrograph shows the microstructure of sol-gel sample contains small particle size with high grain boundaries whereas the microstructure of sample produced via solid state reaction contains large particle size. Furthermore, experimental observation and theoretical calculation done in electrical characterization clarify that the density as well as grain boundaries are significant factors determining the electrical conductivity of CaCu3Mn4O12 samples. The result shows the solid state

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the result of varying the calcination time in solid state reaction shows no significant different in their phase formation, microstructure and conductivity value.

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iii

ABSTRAK

Dalam projek ini, penyediaan CaCu3Mn4O12 telah dijalankan melalui teknik kimia basah

dan tindak balas keadaan pepejal supaya pada penghujung kajian, perbezaan dalam sifat-sifat sampel antara kedua-dua kaedah dapat dijelaskan. Tambahan lagi, dalam teknik tindak balas keadaan pepejal, penyediaan CaCu3Mn4O dilakukan dengan

mempelbagaikan masa yang digunakan untuk proses pengkalsinan yang bertujuan untuk menyiasat kesan kepelbagaian parameter tersebut terhadap sifat-sifat produk. Untuk mencapai objektif projek, kajian dibahagikan kepada dua bahagian; penyediaan CaCu3Mn4O12 menggunakan sol-gel dan tindak balas keadaan pepejal dan ujian ke atas

sampel yang dihasilkan. . Kedua-dua kaedah melibatkan proses yang sama iaitu penyediaan precursor; pencampuran, pengacauan, dan pengeringan dalam kaedah sol-gel manakala dalam tindak balas keadaan pepejal melibatkan pencampuran dan pengisaran bebola, diikuti dengan pengkalsinan, pembentukan dan proses pensinteran. Untuk bahagian yang kedua iaitu ujian ke atas sampel, pengenalan terhadap pembentukan fasa dan analisis ke atas mikrostruktur-mikrostruktur masing-masing dicirikan melalui pembelauan sinar-X (XRD) dan Mikroskop Elektron Pengimbasan (SEM), manakala pencirian ke atas sifat-sifat elektrik dijalankan menggunakan penganalisa impedans. Kajian menunjukkan pembentukan fasa CaCu3Mn4O12 dalam

pola pembelauan sinar-X berlaku pada 600°C dalam sampel sol-gel dan 800°C dalam sampel yang dihasilkan melalui tindak balas keadaan pepejal. Mikrograph SEM menunjukkan mikrostruktur sampel sol-gel mengandungi partikel-partikel yang kecil dan banyak sempadan butir manakala mikrostruktur sampel yang dihasilkan melalui tindak balas keadaan pepejal mangandungi saiz partikel yang besar. Tambahan lagi, pemerhatian eksperimen dan pengiraan secara teori yang dilakukan dalam pencirian elektrik menjelaskan bahawa ketumpatan dan bilangan sempadan butir merupakan

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factor-faktor yang kuat dalam menentukan kekonduksian elektrik dalam sampel CaCu3Mn4O12. Keputusan menunjukkan bahawa sampel yang dihasilkan melalui tindak

balas keadaan pepejal mempunyai nilai kekonduksian yang lebih tinggi berbanding sampel sol-gel. Selain itu, keputusan dalam mempelbagaikan masa untuk proses pengkalsinan menunjukkan tiada perubahan yang ketara dalam pembentukan fasa, mikrostruktur dan nilai kekonduksian.

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DEDICATION

For all your advice and encouragement, this thesis is gratefully dedicated to my family and my friends. Thank you very much for your continuous support and effort towards the publication of this thesis.

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ACKNOWLEDGEMENT

Firstly, Syukur Alhamdulillah and all praises of Allah S.W.T which lead me to accomplish this final year project (Semester II) in a course of BMFG 4923.I would like to express my big appreciation and sincere gratitude to my supervisor, Dr. Mohd Warikh Bin Abd Rashid and to my examiner Pn. Intan Sharhida Bt Othman for their encouragement, ideas and support and for their irreplaceable unfailing patience, guidance throughout this project research. Their knowledge and experience really inspired and spurred myself. Last but least, to technician lab members and whom those involve in completing this projects who have been helping together to give idea and any flourishing suggestions, a special thanks for their sincerely and co-operations. Also big thanks for my family as well as friends without their wise counsel and dependable assistance this project research would not have been possible. Thank you very much.

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vii

Abstract i

Abstrak iii

Dedication v

Acknowledgement vi

Table of Contents vii

List of Tables x

List of Figures xi

List of Abbreviations xiv

1. INTRODUCTION 1

1.1 Introduction to Calcium Cuprum Mangan Oxide (CaCu3Mn4O12) 1

1.2 Problem Statement 3

1.3 Objectives 4

1.4 Scope of the Study 4

2. LITERATURE REVIEW 7

2.1 Electroceramic Material 7

2.2 Perovskite Structure 10

2.3 Cupromanganite (CaCu3Mn4O12) 11

2.4 New Derivatives of CaCu3Mn4O12 12

2.5 The Properties of CaCu3Mn4O12 13

2.5.1 Magnetism of Magnetic Materials 13

2.5.1.1 Ferromagnetism 14

2.5.1.2 Antiferromagnetism 14

2.5.1.3 Ferimagnetism 15

2.5.1.4 Paramagnetism 15

2.5.2 The Phenomenon of Magnetoresistance 16

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viii

2.6 Synthesis Method of CaCu3Mn4O12 18

2.6.1 Producing CaCu3Mn4O12 via Wet and Dry Chemistry 20

2.6.2 Electroceramic Material Processing 22

2.6.2.1 Raw Material 23

2.6.2.2 Mixing, Stirring and Milling 23

2.6.2.3 Evaporating and Drying 24

2.6.2.4 Calcination 25

2.6.2.5 Forming 26

2.6.2.6 Sintering 28

3. METHODOLOGY 31

3.1 Sample Preparation 31

3.1.1 Wet-Chemistry Method – Sol-Gel 31

3.1.1.1 Flow Process of Sol-Gel Method 32

3.1.2 Solid State Reaction Method 38

3.1.2.1 Flow Process of Solid State Reaction Method 38

3.2 Sample Testing 42

3.2.1 X-Ray Diffraction (XRD) Analysis 42

3.2.2 Scanning Electron Microscope (SEM) Observation 44

3.2.3 Electrical Properties Characterization 45

4. RESULT AND DISCUSSION 47

4.1 Material Characterization 48

4.1.1 X-ray Diffraction (XRD) Analysis Results 48

4.1.1.1 Sol-Gel Method 48

4.1.1.2 Solid State Reaction Method 53

4.1.2 Scanning Electron Microscope (SEM) Observation Results 59

4.1.2.1 Sol-Gel Method 59

4.1.2.2 Solid State Reaction Method 63

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5. CONCLUSION AND RECOMMENDATION 75

5.1 Conclusion 75

5.2 Recommendation 76

REFERENCES 77

APPENDICES

A PSM I Gantt Chart B PSM II Gantt Chart

C X-Ray Diffraction Pattern of CaCu3Mn4O12

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LIST OF TABLES

3.1 Stoichiometric amount of raw materials to be used in sol-gel method. 3.2 Stoichiometric amount of raw materials to be used in solid state reaction

method.

4.1 Data table of x-ray diffraction peaks for sol-gel sample.

4.2 Data table of x-ray diffraction peaks for solid state reaction sample (calcined for1½ hours).

33 39

51 58

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LIST OF FIGURES

1.1 Flowchart of scope of study.

2.1 Perovskite structure

2.2 Structure of CaCu3Mn4O12 indicating (a) the MnO6 polyhedral structure;

(b) the cubooctahedral AO12 polyhedra; and (c) the 12-coordinated

polyhedra around the A’ (Cu2+/Mn3+) cation. 2.3 Ferromagnetic ordering.

2.4 Antiferromagnetic ordering. 2.5 Ferrimagnetic ordering.

2.6 Simple illustration of a paramagnetic probe made up from miniature magnets.

2.7 Giant magnetoresistive effect.

2.8 Flow process of CaCu3Mn4O12 synthesis by wet-chemistry method.

2.9 Flow process of CaCu3Mn4O12 synthesis by solid state reaction

method.

2.10 Distribution of liquid among particles during slow drying: (A) before drying, (B) at the early stage of drying, (C) at the end of drying, (D) fully dried.

2.11 Powder pressing method.

2.12 Illustration of change in shape and change of bimodal pore distribution during compaction.

2.13 The sintering process for ceramics. The shrinkage of the workpiece during sintering is due to the elimination of the pores between particles; (a) Green compact, (b) Connecting necks have been formed, (c) Size of pores between particles is greatly reduced particles, (d) Only small pores remain - fully sintered.

3.1 Flow process of sol-gel method.

6 10 12 14 15 15 16 18 21 22 25 26 27 30 32

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xii

3.2 Evaporating process of sample precursor by using heater. 3.3 Calcination profile of sample precursor (sol-gel method). 3.4 Grinding of powder to get into fine powder before compaction. 3.5 Uniaxial hydraulic press machine.

3.6 Filling the powder into pressing machine mold in powder pressing process.

3.7 Sintering profile of the sample pellet (sol-gel method). 3.8 Flow chart of solid state reaction method.

3.9 Calcination profile of precursor powder for 1½ hours (solid

state reaction).

3.10 Calcination profile of precursor powder for 5 hours (solid state reaction).

3.11 Sintering profile of sample pellet for ½ hours (solid state reaction).

3.12 Furnace used for sintering process. 3.13 The flow chart of sample testing process. 3.14 Bruker's X-ray Diffraction D8.

3.15 Sample is placed on a plate to support it during clamping at scanning platform.

3.16 Scanning electron microscope (SEM). 3.17 Impedance Analyzer.

3.18 Clamping of the sample during electrical testing.

4.1 The CaCu3Mn4O12 samples.

4.2 XRD pattern for CaCO3 powder (ICDD 047-1743).

4.3 XRD pattern for CuO powder (ICDD 44-0706).

4.4 XRD patterns for CaCu3Mn4O12 samples synthesized through

sol-gel method.

4.5 XRD pattern of Ca(OH)2 powder.

4.6 XRD pattern of CuO powder. 4.7 XRD pattern of MnO2 powder.

34 35 35 36 36 37 38 40 40 41 41 42 43 44 45 46 46 47 49 49 50 54 54 55

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xiii 4.8 XRD pattern of KClO3 powder.

4.9 XRD patterns for CaCu3Mn4O12 synthesized through solid state

reaction at calcination temperature of 800°C for 1½ hours.

4.10 XRD patterns for CaCu3Mn4O12 synthesized through solid state

reaction at calcination temperature of 800°C for 5 hours.

4.11 SEM image of CaCu3Mn4O12 powder synthesized by sol-gel

method.

4.12 EDS observation on CaCu3Mn4O12 powder synthesized by sol-gel

method.

4.13 SEM image of CaCu3Mn4O12 pellet synthesized by sol-gel method.

4.14 EDS observation on CaCu3Mn4O12 pellet synthesized by sol-gel

method.

4.15 SEM image of CaCu3Mn4O12 powder synthesized by solid state

reaction A.

4.16 EDS observation on CaCu3Mn4O12 powder synthesized by solid

state reaction A.

4.17 SEM image of CaCu3Mn4O12 pellet synthesized by solid state

reaction A.

4.18 EDS observation on CaCu3Mn4O12 pellet synthesized by solid state

reaction A.

4.19 SEM image of CaCu3Mn4O12 powder synthesized by solid state

reaction B.

4.20 EDS observation on CaCu3Mn4O12 powder synthesized by solid

state reaction B.

4.21 SEM image of CaCu3Mn4O12 pellet synthesized by solid state

reaction B.

4.22 EDS observation on CaCu3Mn4O12 pellet synthesized by solid state

reaction B.

4.23 Graph of conductivity value of CaCu3Mn4O12 samples.

4.24 Graph of conductivity versus density of CaCu3Mn4O12 samples.

55 56 56 59 60 61 62 63 64 65 66 68 69 70 71 72 73

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xiv

LIST OF ABBREVIATIONS

CaCu3Mn4O12 - Calcium Cuprum Mangan Oxide

TMOs - Transition Metal Oxides

CCMO - Calcium Cuprum Mangan Oxide

CuO - Copper (II) Oxide

CaCO3 - Calcium Carbonate

Ca(OH)2 - Calcium Hydroxide

MnO2 - Manganese Oxide

KClO3 - Potassium Chlorate

Mn(NO3)2.4H2O - Manganese Nitrate Tetrahydrate

MR - Magnetoresistance

GMR - Giant Magnetoresistance

CMR - Colossal Magnetoresistance

FCC - Face Center Cubic

XRD - X-Ray Diffraction

SEM - Scanning Electron Microscopy

EDS - Energy Dispersive X-Ray Spectroscopy

RT - Room Temperature

σ - Conductivity

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CHAPTER 1

INTRODUCTION

1.1 Introduction to Calcium Cuprum Mangan Oxide (CaCu3Mn4O12)

Materials science and engineering have been at the frontier of technological advancement since the bronze and iron ages. The present information age relies on the development of ‘smart’ and ‘smaller’ magnetic materials for memory, data storage, processing and probing. These magnetic materials can be divided into numerous categories, depending on their origin and applications. One prime example is the transition metal oxides (TMOs) having perovskite (ABO3 type) structure, which form a

vitally important class of materials from the point of view of fundamental physics as well as technological applications (Siwach et al., 2008).

In this project, the research is carried out on one of the perovskite compounds of ABO3

type structure which is CaCu3Mn4O12 (CCMO). This compound which is also an

electroceramic material was first reported by Chenavas et al. Among the rare ferromagnetic and half-metallic oxides, the complex perovskite CaCu3Mn4O12 is

interesting because it exhibits a high magnetoresistive property (Zeng et al., 1999a). CaCu3Mn4O12 belongs to the wide AA’3B4O12 perovskite family phase; where A and B

consists of different cations. In all these compounds, the crystal symmetry is cubic (space group Im3) with a doubling of the ideal ABO3 perovskite cell. The superstructure

is due to the ordering of the A and A’ ions and the distortion of the oxygen sublattice, which leads to a three-dimensional network of strongly tilted BO6 octahedral sharing

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The various physical properties of several manganese perovskite materials have recently been under very active investigation because of the interesting interplay between their magnetic, electronic and structural properties. Most of these phenomena are related to magnetic, charge and orbital orderings of interpenetrating sublattices of Mn3+ and Mn4+ ions in the material. CaCuxMn7-xO12 family is one of the very interesting classes of

perovskite-type manganite materials. The interest on this group of compounds has grown since the discovery of low-field magnetoresistance in CaCu3Mn4O12. The

magnetoresistance of CaCu3Mn4O12 at low fields around room temperature (RT) is

remarkably large and stable with temperature as compared with other CMR (colossal magnetoresistance) manganite materials, which is very important in potential technical applications. CaCu3Mn4O12 is also interesting from its fundamental physical properties.

The crystal lattice contains only Mn4+ ions, so the magnetoresistance cannot be due to the double exchange mechanism which requires charge transfer along the Mn3+–O–Mn

bonds (Przenioslo et al., 2004b).

Magnetoresistance (MR) is the change of electric resistance in the application of magnetic field. Recently, many of the researchers have found a giant magnetoresistance material such as Pr0.7Sr0.04Ca0.26MnO3 (Maignan et al., 1995), LaLCaMnO (L = Y, Gd)

(Martinez et al., 1996), nanostructure Co/Cu/Co (Sakrani et al., 2007) and CaCu3Mn4O12 (Sanchez-Benitez et al., 2006). CaCu3Mn4O12 have received much

attention because of their giant magnetoresistance (GMR) and charge ordering properties. GMR property of these materials finds potential applications in the field of magnetic sensors, in memory applications and in prototype disc drives employing read-head technology.

Recently, the complex perovskite CaCu3Mn4O12 has attracted the attention of the CMR

(Colossal Magnetoresistance) community: it issemiconducting, orders ferromagnetically at 355 K and shows good MR response at room temperature and low fields. This compound and its derivatives are suitable for practical applications due both to the

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magnitude and the thermal stability of their MR around room temperature (Sanchez-Benitez et al., 2004).

1.2 Problem Statement

There is a wide number of publications exist in the literature on the synthesis of CaCu3Mn4O12. This material can be synthesized by either via conventional solid state

reaction or wet chemical method such as co-precipitation method, deposition-precipitation, impregnation, sol-gel, hydrothermal and urea methods. From the previous research, it is noted that the synthesis route of CaCu3Mn4O12 have rarely been employed

by using solid state reaction. This is because the powder prepared through this method is less active in sintering due to high calcination temperature used, and the homogeneity of the powder is often insufficient due to degree of mixing. However, the conventional method has the advantages of relatively low number of processing steps and low process cost (Dao et al., 1992). Low process cost is due to fewer raw materials used in conventional method compared to wet-chemistry.

Producing of CaCu3Mn4O12 by using wet-chemistry technique gives a lot of advantages.

Through wet-chemistry technique, quality of material produced is guarantee. The wet chemical preparation method allows mixing of the components at a molecular level, resulting in materials with high compositional homogeneity and lower sintering temperature (Guohong et al, 2006). Besides, the powder prepared by the wet chemical method has better sintering activity (Dao et al., 1992). Wet chemical preparation such as sol-gel processing also affords greater control over the formation of particular phase and higher purity of the formed phase (Shinji et al., 2002). Furthermore, the wet chemical method has another advantages including preparing crystalline oxides with narrow grain size distribution, producing highly CaCu3Mn4O12 fine powders without calcination at

high temperature and the resulted particles form low agglomeration (Pusit et al., 2004). In contrast with wet chemical preparation, the traditional mixed-oxide solid-state

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reaction method requires a high calcination temperature, usually leading to poor microstructure and properties due to coarsening and agglomerating (Guohong et al, 2006).

In this study, the producing of CaCu3Mn4O12 will be accomplished by using both

wet-chemistry method and conventional solid state reaction method. This is in order to study the characteristic of the samples produced through both methods.

1.3 Objectives

The objectives of this project are:

(a) To produce CaCu3Mn4O12 by using wet and dry chemistry techniques.

(b) To study the phase analysis, microstructural analysis and electrical properties of CaCu3Mn4O12 prepared through both methods.

1.4 Scope of the Study

In this project, there are two synthesize techniques that will be applied to produce complex manganite perovskite CaCu3Mn4O12 which are wet-chemistry technique that is

sol-gel method and solid state reaction method. Two tasks will be carried out in this study; sample preparation and sample testing. In sample preparation, the first method that will be employed to produce CaCu3Mn4O12 is sol-gel method and the second one is

solid state reaction method. For solid state reaction method, two experiments will be conducted to produce CaCu3Mn4O12 where the time for calcination process for both

experiments is varied into 1½ hours and 5 hours. This is in order to see the effect of varying the time for calcination towards the sample produced.

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In the first method which is sol-gel method, the compound will be prepared by mixing the stoichiometric amount of the compositions of calcium carbonate, CaCO3 (99%,

Aldrich), copper oxide, CuO (99.9%, Aldrich), and manganese nitrate tetrahydrate, Mn(NO3)2.4H2O (49.7% w/w aqueous solution, Aldrich). This mixture then will be

dissolved in nitric acid (35%, Aldrich), citric acid (99.8%, Aldrich), and ethylene glycol (99%, Aldrich) and hence will be evaporated and dried which then followed by calcination, forming by pressing and sintering process.

For the second method, solid state reaction, the CaCu3Mn4O12 producing process

involves the mixing of calcium hydroxide, Ca(OH)2, copper oxide, CuO, manganese

oxide, MnO2 and the oxidizing agent that is KClO3. After preparing 30g of precursor

powder, the powder then is divided into two parts where one sample part will undergo calcination at 800°C for 1½ hours and another one part of powder will undergo calcination at the same temperature but for 5 hours. Then, after calcination, the powder will be ground to finite powder and formed into pellet shape by using die pressing. Sintering process of the sample pellet is carried out at 1000°C in furnace afterwards. Lastly, the samples are washed several times with deionized water under ultrasonic conditions to dissolve KCl.

For sample testing task, the samples produced through both methods will be tested and analyzed to study the phase identification, morphology analysis and electrical properties analysis. Here, the phase identification is characterized by X-Ray Diffraction (XRD), the morphology analysis is studied under Scanning Electron Microscope (SEM) observation, and the electrical properties characterization is performed by using impedance analyzer.

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xiv

LIST OF ABBREVIATIONS

CaCu3Mn4O12 - Calcium Cuprum Mangan Oxide

TMOs - Transition Metal Oxides

CCMO - Calcium Cuprum Mangan Oxide

CuO - Copper (II) Oxide

CaCO3 - Calcium Carbonate

Ca(OH)2 - Calcium Hydroxide

MnO2 - Manganese Oxide

KClO3 - Potassium Chlorate

Mn(NO3)2.4H2O - Manganese Nitrate Tetrahydrate

MR - Magnetoresistance

GMR - Giant Magnetoresistance

CMR - Colossal Magnetoresistance

FCC - Face Center Cubic

XRD - X-Ray Diffraction

SEM - Scanning Electron Microscopy EDS - Energy Dispersive X-Ray Spectroscopy

RT - Room Temperature

σ - Conductivity

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CHAPTER 1

INTRODUCTION

1.1 Introduction to Calcium Cuprum Mangan Oxide (CaCu3Mn4O12)

vitally important class of materials from the point of view of fundamental physics as well as technological applications (Siwach et al., 2008).

In this project, the research is carried out on one of the perovskite compounds of ABO3

type structure which is CaCu3Mn4O12 (CCMO). This compound which is also an

electroceramic material was first reported by Chenavas et al. Among the rare ferromagnetic and half-metallic oxides, the complex perovskite CaCu3Mn4O12 is

interesting because it exhibits a high magnetoresistive property (Zeng et al., 1999a). CaCu3Mn4O12 belongs to the wide AA’3B4O12 perovskite family phase; where A and B

consists of different cations. In all these compounds, the crystal symmetry is cubic (space group Im3) with a doubling of the ideal ABO3 perovskite cell. The superstructure

is due to the ordering of the A and A’ ions and the distortion of the oxygen sublattice, which leads to a three-dimensional network of strongly tilted BO6 octahedral sharing

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perovskite-type manganite materials. The interest on this group of compounds has grown since the discovery of low-field magnetoresistance in CaCu3Mn4O12. The

magnetoresistance of CaCu3Mn4O12 at low fields around room temperature (RT) is

The crystal lattice contains only Mn4+ ions, so the magnetoresistance cannot be due to the double exchange mechanism which requires charge transfer along the Mn3+–O–Mn

bonds (Przenioslo et al., 2004b).

(Martinez et al., 1996), nanostructure Co/Cu/Co (Sakrani et al., 2007) and CaCu3Mn4O12 (Sanchez-Benitez et al., 2006). CaCu3Mn4O12 have received much

Recently, the complex perovskite CaCu3Mn4O12 has attracted the attention of the CMR

(Colossal Magnetoresistance) community: it is semiconducting, orders ferromagnetically at 355 K and shows good MR response at room temperature and low fields. This compound and its derivatives are suitable for practical applications due both to the

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magnitude and the thermal stability of their MR around room temperature (Sanchez-Benitez et al., 2004).

1.2 Problem Statement

There is a wide number of publications exist in the literature on the synthesis of CaCu3Mn4O12. This material can be synthesized by either via conventional solid state

by using solid state reaction. This is because the powder prepared through this method is less active in sintering due to high calcination temperature used, and the homogeneity of the powder is often insufficient due to degree of mixing. However, the conventional method has the advantages of relatively low number of processing steps and low process cost (Dao et al., 1992). Low process cost is due to fewer raw materials used in conventional method compared to wet-chemistry.

Producing of CaCu3Mn4O12 by using wet-chemistry technique gives a lot of advantages.

Through wet-chemistry technique, quality of material produced is guarantee. The wet chemical preparation method allows mixing of the components at a molecular level, resulting in materials with high compositional homogeneity and lower sintering temperature (Guohong et al, 2006). Besides, the powder prepared by the wet chemical method has better sintering activity (Dao et al., 1992). Wet chemical preparation such as sol-gel processing also affords greater control over the formation of particular phase and higher purity of the formed phase (Shinji et al., 2002). Furthermore, the wet chemical method has another advantages including preparing crystalline oxides with narrow grain size distribution, producing highly CaCu3Mn4O12 fine powders without calcination at

high temperature and the resulted particles form low agglomeration (Pusit et al., 2004). In contrast with wet chemical preparation, the traditional mixed-oxide solid-state

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reaction method requires a high calcination temperature, usually leading to poor microstructure and properties due to coarsening and agglomerating (Guohong et al, 2006).

In this study, the producing of CaCu3Mn4O12 will be accomplished by using both

wet-chemistry method and conventional solid state reaction method. This is in order to study the characteristic of the samples produced through both methods.

1.3 Objectives

The objectives of this project are:

(a) To produce CaCu3Mn4O12 by using wet and dry chemistry techniques.

(b) To study the phase analysis, microstructural analysis and electrical properties of CaCu3Mn4O12 prepared through both methods.

1.4 Scope of the Study

In this project, there are two synthesize techniques that will be applied to produce complex manganite perovskite CaCu3Mn4O12 which are wet-chemistry technique that is

solid state reaction method. For solid state reaction method, two experiments will be conducted to produce CaCu3Mn4O12 where the time for calcination process for both

experiments is varied into 1½ hours and 5 hours. This is in order to see the effect of varying the time for calcination towards the sample produced.

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In the first method which is sol-gel method, the compound will be prepared by mixing the stoichiometric amount of the compositions of calcium carbonate, CaCO3 (99%,

Aldrich), copper oxide, CuO (99.9%, Aldrich), and manganese nitrate tetrahydrate, Mn(NO3)2.4H2O (49.7% w/w aqueous solution, Aldrich). This mixture then will be

For the second method, solid state reaction, the CaCu3Mn4O12 producing process

involves the mixing of calcium hydroxide, Ca(OH)2, copper oxide, CuO, manganese

oxide, MnO2 and the oxidizing agent that is KClO3. After preparing 30g of precursor

Producing Calcium Cuprum Mangan Oxide (CaCu3Mn4O12) Via Wet And Dry Chemistry Techniques.