Study of the magnetic and electrical properties of some garnet ferrites
Ahmed Mohamed Ahmed Ali Faramawy;
Abstract
Rare earth (RE) garnets are complex ceramic oxides that have a cubic crystal structure of the space group Oh(10)-Ia3d.The cations are arranged on three crystallographic sublattices namely c- sites (dodecahedral), d-sites (octahedral) and a-sites (tetrahedral).Gadolinium Yttrium Iron Garnet (GdYIG) samples with the chemical formula (GdxY3−xFe5O12) (x= 0.0, 0.25, 0.5, 0.75, and 1.0) were prepared via two different methods, the standard ceramic method (SC) and the co-precipitation method (CP). The effects of preparation conditions and Gd3+ ion substitution on the phase formation, crystal structure,morphology, magnetic and dielectric properties were studied. Moreover, therelative permeability μrand Curie temperature Tcwere measured for all investigated samples.
The present thesis contains four chapters:
Chapter 1: It includes the fundamental basics of magnetic materials specially the garnet ferrites. Moreover, it illustrates the structure and its relation with the magnetic and electrical properties.
Chapter 2: This chapter is devoted toliterature survey for ideas carried out in last few years. It is focused on the different processing methods and different dopants that enhanced the properties of garnet ferrites specially Gadolinium Yttrium Iron Garnet (GdYIG).
Chapter 3: This chapter deals with experimental work and involves materials, preparation [Standard ceramic (SC) and co-precipitation (CP) methods], characterization [X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infra-red (FT-IR)], magnetization measurements using vibrating sample magnetometer (VSM), relative permeability, magnetic loss and dielectric measurements.
Chapter 4: This chapter deals with the results and discussion: formation of single phase Gadolinium Yttrium Iron Garnet (GdYIG)using Standard ceramic (SC) and co-precipitation (CP) methods. Moreover, the effect of Gd3+ ion substituted YIG on its different properties was demonstrated.
The main results are:
1. A single phase of GdxY3-xFe5O12(x= 0, 0.25, 0.5, 0.75 and 1) was prepared by two different methods, standard ceramic (SC) and the co-precipitation (CP) methodexcept a small percentage of perovskite phase (yttrium orthoferrite) (YFeO3) in CP samples.
2. For both methods, the lattice parameter increases on addition of Gd3+ ion while the porosity decreases.
3. There is a good agreement between theoretical lattice parameter values ‘‘ath’’ and experimental values ‘‘aexp’’ of SC samples. On the other hand, the lattice parameter of the samples prepared by CP method is higher than that prepared by SC method.
4. It was founded that the crystallite sizes of the samples prepared by (CP) method are generally smaller than those prepared by (SC) method.
5. The IR spectra indicated the occupation of Fe2+ for both tetrahedral and octahedral while both of Y3+ and Gd3+ ions occupy the dodecahedral site showed that by increasing Gd concentration the corresponding peak was shifted to the lower frequency for both methods.
6. The morphology, using the field emission scanning electron micrographs (FESEM),showed that the particles of the samples prepared by CP method are quasi round in shape and quite uniformly distributed. On the other hand, the samples prepared by SC method have non-uniform shape morphology. It was observed that the particle size increases with increasing Gd+3 concentration and the values of SC samples are greater than those of CP ones.
7. Increasing Gd3+ concentration leads to the decrease ofthe saturation magnetization Ms in both methods. Moreover, the values for CP samples are less than those for SC samples. Also the coercivity values Hc for CP samples were higher than those prepared by SC method.
8. The relative permeability (μr) decreased by increasing Gd+3 ions for both systems while Curie temperatures (Tc) increased. On the other hand, (μr) and (Tc) were found to be higher in samples prepared by (SC) method than ones prepared by (CP) method.
9. The heating ability of all investigated samples increases with increasing the Gd concentration and it is higher in samples prepared via (SC) samples than (CP) ones which make these samples applicable for using in cancer therapy and cancer diagnosis.
10. The resistivity has an increasing trend with Gd concentration in (SC) and (CP) samples while the real part (permittivity) and the imaginary part (dielectric loss) decrease by increasingGd concentration.
11. The values of resistivity in (CP) samples were higher than that in (SC) samples.
12. The dielectric loss decreases in CP samples than in SCsamples which is a very interesting property in micro wave applications.
The present thesis contains four chapters:
Chapter 1: It includes the fundamental basics of magnetic materials specially the garnet ferrites. Moreover, it illustrates the structure and its relation with the magnetic and electrical properties.
Chapter 2: This chapter is devoted toliterature survey for ideas carried out in last few years. It is focused on the different processing methods and different dopants that enhanced the properties of garnet ferrites specially Gadolinium Yttrium Iron Garnet (GdYIG).
Chapter 3: This chapter deals with experimental work and involves materials, preparation [Standard ceramic (SC) and co-precipitation (CP) methods], characterization [X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infra-red (FT-IR)], magnetization measurements using vibrating sample magnetometer (VSM), relative permeability, magnetic loss and dielectric measurements.
Chapter 4: This chapter deals with the results and discussion: formation of single phase Gadolinium Yttrium Iron Garnet (GdYIG)using Standard ceramic (SC) and co-precipitation (CP) methods. Moreover, the effect of Gd3+ ion substituted YIG on its different properties was demonstrated.
The main results are:
1. A single phase of GdxY3-xFe5O12(x= 0, 0.25, 0.5, 0.75 and 1) was prepared by two different methods, standard ceramic (SC) and the co-precipitation (CP) methodexcept a small percentage of perovskite phase (yttrium orthoferrite) (YFeO3) in CP samples.
2. For both methods, the lattice parameter increases on addition of Gd3+ ion while the porosity decreases.
3. There is a good agreement between theoretical lattice parameter values ‘‘ath’’ and experimental values ‘‘aexp’’ of SC samples. On the other hand, the lattice parameter of the samples prepared by CP method is higher than that prepared by SC method.
4. It was founded that the crystallite sizes of the samples prepared by (CP) method are generally smaller than those prepared by (SC) method.
5. The IR spectra indicated the occupation of Fe2+ for both tetrahedral and octahedral while both of Y3+ and Gd3+ ions occupy the dodecahedral site showed that by increasing Gd concentration the corresponding peak was shifted to the lower frequency for both methods.
6. The morphology, using the field emission scanning electron micrographs (FESEM),showed that the particles of the samples prepared by CP method are quasi round in shape and quite uniformly distributed. On the other hand, the samples prepared by SC method have non-uniform shape morphology. It was observed that the particle size increases with increasing Gd+3 concentration and the values of SC samples are greater than those of CP ones.
7. Increasing Gd3+ concentration leads to the decrease ofthe saturation magnetization Ms in both methods. Moreover, the values for CP samples are less than those for SC samples. Also the coercivity values Hc for CP samples were higher than those prepared by SC method.
8. The relative permeability (μr) decreased by increasing Gd+3 ions for both systems while Curie temperatures (Tc) increased. On the other hand, (μr) and (Tc) were found to be higher in samples prepared by (SC) method than ones prepared by (CP) method.
9. The heating ability of all investigated samples increases with increasing the Gd concentration and it is higher in samples prepared via (SC) samples than (CP) ones which make these samples applicable for using in cancer therapy and cancer diagnosis.
10. The resistivity has an increasing trend with Gd concentration in (SC) and (CP) samples while the real part (permittivity) and the imaginary part (dielectric loss) decrease by increasingGd concentration.
11. The values of resistivity in (CP) samples were higher than that in (SC) samples.
12. The dielectric loss decreases in CP samples than in SCsamples which is a very interesting property in micro wave applications.
Other data
| Title | Study of the magnetic and electrical properties of some garnet ferrites | Other Titles | دراسة الخواص المغناطيسية والكهربية لبعض فيريتات الجارنت | Authors | Ahmed Mohamed Ahmed Ali Faramawy | Issue Date | 2016 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.