I= SOCIO – ECONOMIC CONSEQUENCES OF RETURN MIGRATION AND THE ADJUSTMENT PROBLEMS IN PUNJAB Title of Thesis


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Title of Thesis

MAGNETIC AND ELECTRICAL PROPERTIES OF FERRITES

Author(s)

Muhammad Ashfaq

Institute/University/Department Details

Bahauddin Zakariya University, Multan / Materials Science

Session

October 2001

Subject

Materials Science

Number of Pages

79

 

Keywords (Extracted from title, table of contents and abstract of thesis)

Ferrites, Cobalt Zinc Series, Cucd Series, Ferromagnetic, Cuo.75Cdo.25 Fe2O4 system

 

Abstract

Three series of the spinel ferrites i.e. Cobalt Zinc series, CuCd series with varying concentrations of Zn and Cd respectively and Cuo.75sCdo.25Fe2O4 with different particle sizes were prepared by standard ceramic technique. Magnetic and electrical properties of these spinel ferrites have been studied. All the samples exist in fcc structure. The lattice constant of all these samples follow Vegard’s slaw. Calculation of oxygen positional parameter and cation distribution reveals that these samples belong to the family of the mixed or partially inverse ferrites. Temperature dependent electrical resistively of all the samples exhibits semi-conducting behavior of these ferrites. The activation energies obtained from Arrhenius plots rule out the band type conduction in these ferrites. A hopping conduction is rather dominant. Results of measurement of thermo power show that most of the samples are degenerate semiconductors. Both n and p-type carriers contribute in the conduction mechanism. Ac susceptibility measurement by mutual Inductance technique was used to determine the Curie temperature, effective magnetic moments, and the g-values. The I/X vs. T plots follow Curie-Weiss law at high temperature and show deviations from this behavior below Curie temperature. The paramagnetic Curie temperature has also been measured from I/X vs. T plots to calculate the strength of dominant interaction in all these systems. The negative values of 8(K) indicate that the dominant interaction in all the samples is antiferromagntic. Weakening of the AB-interaction is observed from compositional variation and cation distribution results in cobalt zinc and copper cadmium ferrite systems due to the canting of spins of the Y-K type on B-sites. Where as AB- interaction is enhanced in the case of Cuo.75Cdo.25 Fe2O4 system with the variation of particle sizes due to decreasing value of the Y-K angles. Compositional variation of the intrinsic properties like saturation magnetization, remanance, and coercively were studied using M-H loops obtained from a VSM. The increase in saturation magnetization, remanence as a function of composition is due to strong AB-interaction and decrease in these intrinsic properties as a function of composition is attributed to the weakening of the AB-interaction, decrease in magnetic moments and the presence of Y-K angles in ferrites.

 

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    Table of Contents  

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1 1 INTRODUCTION 1

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2 2 THEORIES AND MODELS 6

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3 3 EXPERIMENTAL TECHNIQUES 46

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4 4 RESULTS AND DISCUSSIONS 54

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5 5 REFERENCES

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6 6 PUBLICATIONS

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7 7 C.V

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8 8 TABLE

95

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9 9 FIGURES

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