Advanced Ferrite Technology Properties and Applications

This book contains some of the magnetic, the electric and the dielectric properties of the mixed Cu-Zn spinel ferrite. The material covered in this book is divided into two parts: They are theoretical part I and experimental part II. Part I contains six chapters, that cover description of magnetic materials in chapter 1, structure properties of ferrimagnetic materials in chapter 2, magnetic properties of ferrimagnetic materials in chapter 3 , electric and dielectric properties of ferrimagnetic materials in chapter 4, applications of ferrimagnetic materials in chapter 5 and finally literature survey in chapter 6. Part II divides into four chapters that describe method, techniques, and results. These chapters, also, discuss the structure of the mixed Cu-Zn spinel ferrite and the effects of the 2 Zn ions of the mixed Cu-Zn spinel ferrite on magnetic, the electric and the dielectric properties. Chapter 7 covers of the preparation of mixed Cu-Zn spinel ferrite, which have the chemical formula 1 s s 2 4 Cu Zn Fe O , where s stepped by 0.2 according to Advanced Ferrite Technology Preface ix ( 0.0 s 1.0), were prepared from purity metal oxides using the standard ceramic. It, also, exhibits the experimental techniques and the apparatus for different measurements. Chapter 8 illustrates the infrared IR spectra for the ferrite samples in the frequency range 1 (200 1000) cm . Two main absorption bands were observed which indicate the formation of spinel ferrite compound. In addition, two small absorption bands were, also, observed. Their positions and intensities were found to be strongly depending on the s-value. On the basis of the IR spectra analyzation, the crystal structure and cations distribution were deduced for the ferrite samples. Chapter 9 covers the magnetic properties for the ferrite samples using Faraday’s law of the electromagnetic induction. The ferrite samples were used to find the magnetization at room temperature in the range of the applied magnetic field which was varied from 0 1 . Am up to 510 1 . Am . The obtained results illustrate that, as the 2 Zn ions increased the magnetization increasing for the ferrite samples with s 0.6 , where it decreased for the ferrite samples with s > 0.6. The observed results of the magnetic properties were in good agreement with several studies for various ferrite compounds [1-3]. We adapted Yafet and Kittel model [4] and Neel’s theory [5] to explain the observed results. The initial permeability for the ferrite samples was determined as a function of temperature. It increased with increasing of temperature, then, it decreased abruptly close to Curie temperature point. Utilizing the initial permeability data, the Curie temperature points were estimated for all the ferrite samples. It decreased by the addition of the 2 Zn Advanced Ferrite Technology Preface x ions. The magnetic properties were found to be affected by the intensity of the applied magnetic field, the s-value and temperature. Finally, chapter 10 exhibits the AC conductivity for the ferrite samples in the applied frequency of the range(10 10 )Hz 4 6 . In this range frequency, the AC conductivity increased continuously with increasing of the applied frequency. The dielectric properties for the ferrite samples were determined at room temperature as a function of the applied frequency in the range(10 10 )Hz 4 6 . The general trend for all samples was found to decrease continuously with increasing of the applied frequency. The DC resistivity was determined for the ferrite samples in temperature range which varied from 300K up to 730K. The variation of the logarithm of resistivity DC ln with the reciprocal of temperature (1/T) showed that, resistivity continuously decreased with increasing of temperature. On the other hand, the plot of DC ln versus (1/T) indicated more than one slope. This change of the slope is attributed to the existence of different competing conduction mechanisms. The measurements of the electric and the dielectric properties exhibited that, the behavior of the ferrite samples is the same as that of the semiconductor materials. The results of the electric and dielectric properties were in good agreement with previous studies for various ferrite compounds [6-10]. The electron hopping model [11] was used to explain the electric conductivity for the ferrite samples. The electric and the dielectric properties were found to be affected by the s-value, temperature and frequency of the applied magnetic field. Advanced Ferrite Technology Preface xi This book exhibited that, the non-magnetic 2 Zn ions have great effects on the magnetic, the electric and the dielectric properties of the Cu spinel ferrite. In the light of the different theories and results of chapters in the part I and II the prominent properties of ferrites make them very promising a candidate versatile. A study of polycrystalline ferrites is important in view of their successively extensively used as core materials over a wide range of frequency for numerous electronic devices and electrical components. This is due to their high initial permeability, large resistivity, high dielectric constant and low dielectric loss. In fact, the mixed Cu-Zn spinel ferrite is considered a soft ferrite material, which is proved to be an interest material for technological and scientific applications.This book contains some of the magnetic, the electric and the dielectric properties of the mixed Cu-Zn spinel ferrite. The material covered in this book is divided into two parts: They are theoretical part I and experimental part II. Part I contains six chapters, that cover description of magnetic materials in chapter 1, structure properties of ferrimagnetic materials in chapter 2, magnetic properties of ferrimagnetic materials in chapter 3 , electric and dielectric properties of ferrimagnetic materials in chapter 4, applications of ferrimagnetic materials in chapter 5 and finally literature survey in chapter 6. Part II divides into four chapters that describe method, techniques, and results. These chapters, also, discuss the structure of the mixed Cu-Zn spinel ferrite and the effects of the 2 Zn ions of the mixed Cu-Zn spinel ferrite on magnetic, the electric and the dielectric properties. Chapter 7 covers of the preparation of mixed Cu-Zn spinel ferrite, which have the chemical formula 1 s s 2 4 Cu Zn Fe O , where s stepped by 0.2 according to Advanced Ferrite Technology Preface ix ( 0.0 s 1.0), were prepared from purity metal oxides using the standard ceramic. It, also, exhibits the experimental techniques and the apparatus for different measurements. Chapter 8 illustrates the infrared IR spectra for the ferrite samples in the frequency range 1 (200 1000) cm . Two main absorption bands were observed which indicate the formation of spinel ferrite compound. In addition, two small absorption bands were, also, observed. Their positions and intensities were found to be strongly depending on the s-value. On the basis of the IR spectra analyzation, the crystal structure and cations distribution were deduced for the ferrite samples. Chapter 9 covers the magnetic properties for the ferrite samples using Faraday’s law of the electromagnetic induction. The ferrite samples were used to find the magnetization at room temperature in the range of the applied magnetic field which was varied from 0 1 . Am up to 510 1 . Am . The obtained results illustrate that, as the 2 Zn ions increased the magnetization increasing for the ferrite samples with s 0.6 , where it decreased for the ferrite samples with s > 0.6. The observed results of the magnetic properties were in good agreement with several studies for various ferrite compounds [1-3]. We adapted Yafet and Kittel model [4] and Neel’s theory [5] to explain the observed results. The initial permeability for the ferrite samples was determined as a function of temperature. It increased with increasing of temperature, then, it decreased abruptly close to Curie temperature point. Utilizing the initial permeability data, the Curie temperature points were estimated for all the ferrite samples. It decreased by the addition of the 2 Zn Advanced Ferrite Technology Preface x ions. The magnetic properties were found to be affected by the intensity of the applied magnetic field, the s-value and temperature. Finally, chapter 10 exhibits the AC conductivity for the ferrite samples in the applied frequency of the range(10 10 )Hz 4 6 . In this range frequency, the AC conductivity increased continuously with increasing of the applied frequency. The dielectric properties for the ferrite samples were determined at room temperature as a function of the applied frequency in the range(10 10 )Hz 4 6 . The general trend for all samples was found to decrease continuously with increasing of the applied frequency. The DC resistivity was determined for the ferrite samples in temperature range which varied from 300K up to 730K. The variation of the logarithm of resistivity DC ln with the reciprocal of temperature (1/T) showed that, resistivity continuously decreased with increasing of temperature. On the other hand, the plot of DC ln versus (1/T) indicated more than one slope. This change of the slope is attributed to the existence of different competing conduction mechanisms. The measurements of the electric and the dielectric properties exhibited that, the behavior of the ferrite samples is the same as that of the semiconductor materials. The results of the electric and dielectric properties were in good agreement with previous studies for various ferrite compounds [6-10]. The electron hopping model [11] was used to explain the electric conductivity for the ferrite samples. The electric and the dielectric properties were found to be affected by the s-value, temperature and frequency of the applied magnetic field. Advanced Ferrite Technology Preface xi This book exhibited that, the non-magnetic 2 Zn ions have great effects on the magnetic, the electric and the dielectric properties of the Cu spinel ferrite. In the light of the different theories and results of chapters in the part I and II the prominent properties of ferrites make them very promising a candidate versatile. A study of polycrystalline ferrites is important in view of their successively extensively used as core materials over a wide range of frequency for numerous electronic devices and electrical components. This is due to their high initial permeability, large resistivity, high dielectric constant and low dielectric loss. In fact, the mixed Cu-Zn spinel ferrite is considered a soft ferrite material, which is proved to be an interest material for technological and scientific applications

Observation of eliminative cationic polymerization within van der Waals clusters

We report the first observation of eliminative cationic polymerization within van der Waals (vdW) clusters following electron impact ionization at pressures of 10−8 Torr. The elimination reactions of C2H3Cl+ within the clusters terminate after three successive steps, each involving elimination of HCl or Cl. The results provide a mechanism for the early stages of gas phase cationic polymerization of vinyl chloride and demonstrate the feasibility of using vdW clusters as a means of studying gas phase cationic polymerization

AC Conductivity and Dielectric Properties of Cu–Zn ferrites

In this work, we have studied the effects of the 2 Zn ions on the electric and the dielectric properties of the Cu spinel ferrite. The mixed Cu-Zn spinel ferrite, of chemical formula 1 s s 2 4 Cu Zn Fe O , where s stepped by 0.2 according to ( 0.0 s 1.0), were prepared from purity metal oxides using the standard ceramic preparation. The AC conductivity was determined for the ferrite samples in the applied frequency range (10 10 )Hz 4 6 . In this range of frequency, the AC conductivity increases rapidly as a function of the applied frequency. The dielectric properties for the ferrite samples were also determined at room temperature. The general trend for all samples was found to decrease continuously with increasing of the applied frequency. The measurements of the electric and the dielectric properties show that, the behavior of the ferrite samples is similar to that of the semiconductor materials. The results of the electric and dielectric properties are inadequate to previous studies for various ferrite compounds. The electric conductivity for the samples was explained using the electron hopping model.In this work, we have studied the effects of the 2 Zn ions on the electric and the dielectric properties of the Cu spinel ferrite. The mixed Cu-Zn spinel ferrite, of chemical formula 1 s s 2 4 Cu Zn Fe O , where s stepped by 0.2 according to ( 0.0 s 1.0), were prepared from purity metal oxides using the standard ceramic preparation. The AC conductivity was determined for the ferrite samples in the applied frequency range (10 10 )Hz 4 6 . In this range of frequency, the AC conductivity increases rapidly as a function of the applied frequency. The dielectric properties for the ferrite samples were also determined at room temperature. The general trend for all samples was found to decrease continuously with increasing of the applied frequency. The measurements of the electric and the dielectric properties show that, the behavior of the ferrite samples is similar to that of the semiconductor materials. The results of the electric and dielectric properties are inadequate to previous studies for various ferrite compounds. The electric conductivity for the samples was explained using the electron hopping model

Synthesis and characterization of white light emitting CaxSr1-xAl2O4:Tb3+,Eu3+ phosphor for solid state lighting

A white light emitting CaxSr1-xAl2O4:Tb3+;Eu3+ phosphor was synthesized by a combustion method using metal nitrates as precursors and urea as a fuel. The X-ray diffraction patterns from the samples showed phases associated with monoclinic structures of CaAl2O4 and SrAl2O4. White photoluminescence with the CIE coordinates (x = 0.343, y = 0.325) was observed when the phosphor was optically-excited at 227 nm using a monochromatized xenon lamp. The white photoluminescence was a result of the combination of blue and green line emissions from Tb3+, and red line emission from Eu3+. The structure and photoluminescence properties of this phosphor are reported.The authors would like to acknowledge the financial support from the cluster funds of the University of the Free State and the South African National Research Foundation.A white light emitting CaxSr1-xAl2O4:Tb3+;Eu3+ phosphor was synthesized by a combustion method using metal nitrates as precursors and urea as a fuel. The X-ray diffraction patterns from the samples showed phases associated with monoclinic structures of CaAl2O4 and SrAl2O4. White photoluminescence with the CIE coordinates (x = 0.343, y = 0.325) was observed when the phosphor was optically-excited at 227 nm using a monochromatized xenon lamp. The white photoluminescence was a result of the combination of blue and green line emissions from Tb3+, and red line emission from Eu3+. The structure and photoluminescence properties of this phosphor are reported

White cathodoluminescence from Zn0.3Mg0.7Al2O4:Tb3+,Eu3+.

In this study, white cathodoluminescence (CL) was generated from Zn0.3Mg0.7Al2O4:Tb3+;Eu3+ prepared by the combustion route using urea as a fuel metal and nitrates as precursors. The X-ray diffraction (XRD) patterns from the samples showed phases associated with cubic structures of ZnAl2O4 and MgAl2O4. The particle morphology of the Zn0.3Mg0.7Al2O4:Tb3+;Eu3+ showed different irregular shapes. White CL with the CIE coordinates (x = 0.343, y = 0.323) was observed when the phosphor was excited by a low voltage (2 keV) electron beam in vacuum. This was a result of the simultaneous emission of blue and green emissions from Tb3+, and red emission from Eu3+. This phosphor is evaluated for possible applications in white LEDs. .The authors would like to acknowledge the financial support from the cluster funds of the University of the Free State, the South African National Research Foundation (NRF), the South African National Laser centre (NLC), and the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation of South Africa.In this study, white cathodoluminescence (CL) was generated from Zn0.3Mg0.7Al2O4:Tb3+;Eu3+ prepared by the combustion route using urea as a fuel metal and nitrates as precursors. The X-ray diffraction (XRD) patterns from the samples showed phases associated with cubic structures of ZnAl2O4 and MgAl2O4. The particle morphology of the Zn0.3Mg0.7Al2O4:Tb3+;Eu3+ showed different irregular shapes. White CL with the CIE coordinates (x = 0.343, y = 0.323) was observed when the phosphor was excited by a low voltage (2 keV) electron beam in vacuum. This was a result of the simultaneous emission of blue and green emissions from Tb3+, and red emission from Eu3+. This phosphor is evaluated for possible applications in white LEDs.

FT-IR Studies of Nickel Substituted Polycrystalline Zinc Spinel Ferrites for Structural and Vibrational Investigations

FT-IR spectra of Ni1-sZnsFe2O4 spinel ferrite, s changed by 0.2 according to 0.0 s 1.0, have been analyzed in the frequency range (350−1000) cm-1. Six polycrystalline ferrites samples were synthesized using the conventional standard double sintering ceramic method. Two main absorption bands were observed, their positions were found to be strongly dependent on s-value. The high frequency band in the range 550-600 cm−1 and a low frequency band at around 400 cm−1 were assigned to tetrahedral Td and octahedral Oh sites, respectively, of spinel lattice. Force constant (FC) was calculated for Tdand Oh sites and was found to decrease with increasing Zn ions. Threshold frequency nth for the electronic transition was determined and found to increase with increasing Zn ions. Cations distribution for the prepared mixed ferrite was concluded based on the FT-IR spectra. The ionic radii for each site were correlated to the cations distribution of the given ferrite.FT-IR spectra of Ni1-sZnsFe2O4 spinel ferrite, s changed by 0.2 according to 0.0 s 1.0, have been analyzed in the frequency range (350−1000) cm-1. Six polycrystalline ferrites samples were synthesized using the conventional standard double sintering ceramic method. Two main absorption bands were observed, their positions were found to be strongly dependent on s-value. The high frequency band in the range 550-600 cm−1 and a low frequency band at around 400 cm−1 were assigned to tetrahedral Td and octahedral Oh sites, respectively, of spinel lattice. Force constant (FC) was calculated for Tdand Oh sites and was found to decrease with increasing Zn ions. Threshold frequency nth for the electronic transition was determined and found to increase with increasing Zn ions. Cations distribution for the prepared mixed ferrite was concluded based on the FT-IR spectra. The ionic radii for each site were correlated to the cations distribution of the given ferrite