Sintering Temperature Effect on Microstructure and Magnetic Evolution Properties with Nano- and Micrometer Grain Size in Ferrite Polycrystals

The morphology and evolution of magnetic properties in multisample sintering (MSS) of yttrium iron garnet (Y3Fe5O12, YIG) and single-sample sintering (SSS) of nickel zinc ferrite (Ni0.6Zn0.4Fe2O4, NZF) were studied in detail, focusing on the parallel evolving relationship with their dependences on sintering temperature. Sintering is an important process in ferrite fabrication which involved the process of transforming a noncrystalline powder into a polycrystalline solid by heating process. Under the influence of heat, the surface area is reduced through the formation and growth of bond between the particles associated with reduction in surface energy. This makes the particles move closer, grains to form by the movement of grain boundaries to grow over pores, and results in decreasing the porosity and increasing the density of the sample. Technological applications, especially in electronics applications, require high-density nanostructured ferrites, integrated by sintering from nanoparticles. The evolution from low to high sintering temperature will result in the transition from disordered to ordered ferromagnetism behavior. Multisample sintering (MSS) of yttrium iron garnet (Y3Fe5O12, YIG) and single-sample sintering (SSS) of nickel zinc ferrite (Ni0.6Zn0.4Fe2O4, NZF) have been used as a studied material in this research work

Study the iron environments of the steel waste product and its possible potential applications in ferrites

In this project, the permanent magnets ferrites have been prepared by recycle the steel waste product. Steel waste is an impure material that contains the iron oxides and impurities. The steel waste product is a form of flakes is grinding for several hours to form a fine powder. The iron oxides powders are separated from magnetic and non-magnetic particle using magnetic particle separation. The magnetic particles was again been purified by using the Curie temperature separation. The magnetic powder carried out from the purification was heated at 500 o C for 6 hours at 6 o C/ mins to form hematite, Fe 2 O 3. The constitute amount of BaCO 3 and Fe 2 O 3 derived by steel waste product are mixed by using mechanical alloying to prepare the barium hexaferrites (BaFe 12 O 19). The samples were sintered at different temperature 600/800/1000/1200 o C for 6 hours at 6 o C/ mins. The composition of FeO, Fe 3 O 4 and Fe 2 O 3 of the steel waste product was carried out using X-ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDAX). The crystallography of sample is observed by using X-ray Diffraction (XRD). Microstructure of samples was carried out by using Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). The saturation magnetization, Curie temperature and density are also observed. The results show the purification process yields high purity of hematite, Fe 2 O 3. The common characteristics of the steel waste product are its low cost, availability and thus the potential for large production volumes, need for recycling, and tendency to further oxidation in the production of ferrites

Structural, phase development and magnetic behavior of polycrystalline yttrium iron garnet

The interest of this work is to investigate the influence of sintering temperatures on the structural, phase development and the magnetic properties of polycrystalline yttrium iron garnet (Y3Fe5O12, YIG). The samples were prepared using α-Fe2O3 and Y2O3 as starting powders by employing a high-energy ball milling (HEBM) technique using a SPEX8000D mill and milled for 9 h. The samples were sintered for 9 h from 500 °C to 1400 °C with increments of 100 °C. Particle size analysis was carried out using a Transmission electron microscope (TEM). The phase development and crystallography study were determined using X-ray Diffractometer (XRD). Field emission scanning electron microscope (FeSEM) was used to study the morphology and microstructural evolutions of YIG. Parallel evolution on magnetic permeability components and Curie temperature were characterized by impedance analyzer. Magnetization-hysteresis (M-H) curve parameters were obtained from a vibrating sample magnetometer (VSM). The change in particle size from nano to micro was also studied with respect to sintering temperatures, structural, phase development and magnetic properties

Preparation and characterization of Sr1−xNdxFe12O19 derived from steel-waste product via mechanical alloying

Steel waste product had been used as the main source of raw material in the preparation of permanent magnets ferrites. Steel waste product is an impure material that contains the iron oxide and impurities. The steel waste product is a form of flakes is grinding for several hours to form a fine powder. The iron oxide powder is separated from magnetic and non-magnetic particle using magnetic particle separation. The magnetic particle was again been purified by using the Curie temperature separation technique. The magnetic powder was carried out from the purification and oxidize at 500 °C for 6 hours at 2 °C/ mins to form the hematite, Fe2O3, used as a raw powder to prepare SrFe12O19. Microstructure of Nd-doped strontium ferrites, Sr1-xNdxFe12O19, with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5, were prepared through a mechanical alloying technique. Several characterizations have been done, such as X-ray Diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The magnetic properties of coercivity (Hc) and the energy product BHmax of samples are carried out. The magnetic properties of samples were investigated with an expectation of enhancing the magnetic properties by substitutions of Nd3+ ions on Fe3+ ion basis sites. The saturation magnetization Ms revealed magnetic behavior with respect to Nd3+ doping concentration, showing a decrease. The coercivity Hc increased with increasing Nd3+ doping concentration

Magnetic properties and microstructures of cobalt substituted barium hexaferrites derived from steel waste product via mechanical alloying technique

The mechanical alloying technique was used to prepare barium hexaferrite (BaM) with 3, 5, 10 and 20 wt% cobalt oxide (Co3O4). In this work, steel waste flakes were cold-rolling steel mill for several hours to form a fine powder. The steel waste powder was purified by using magnetic separation to isolate the magnetic and non magnetic particles. The method was continued for Curie temperature separation technique to separate the magnetic ions by varied Curie temperature of the magnetic powder. The purified powder was then oxidize at 500 °C at 6 °C/mins to form hematite, Fe2O3. The steel waste-derived hematite was used as the raw material in preparing BaM ferrites. The BaCO3, Fe2O3and different percentages of Co3O4 (Co) were mixed and milled for several hours by using mechanical alloying. The powder were pelletised in 11 × 1 mm (diameter × height) and the sintered at 1200 °C for 10 hours. The addition of Co2+/3+ ions to the BaM shows a varying in the magnetic properties of BaM. By increasing the Co doping, the remanence Mr was reduced from 17.6 emu/g to 6.2 emu/g. The coercivity Hc results varying magnitude from 102 Oe to 1079 Oe. The Mr and Hc of undoped BaM is obtain at 14.6 emu/g and 860 Oe, respectively. The grain size of BaM also increases with Co doping. The densities of the compounds are decreasing with increasing Co doping with a maximum value of 4.2 g/cm3

Effect of variation sintering temperature on magnetic permeability and grain sizes of Y3Fe5O12 via mechanical alloying technique

This work will focus on the preparation of yttrium iron garnet (Y3Fe5O12, YIG) via mechanical alloying technique derive by steel waste product. The Fe2O3 powder derived from the steel waste purified by using magnetic and non-magnetic particles (MNM) and Curie temperature separation (CTS) technique. The purified powder was then oxidized in air at 500 °C for 9 hours in air. The Fe2O3 was mixed with Y2O3 using high energy ball milling for 9 hours. The mixed powder obtained was pressed and sintered at different temperature 500/600/700/800/900/1000/1100 °C. X-ray diffraction (XRD) shows the YIG is completely form at 1100 °C. The field emission scanning electron microscopy (FESEM) images shows the grain size increases as increase the sintering temperatures. The frequency dependence on the complex permeability, µ’ and magnetic loss, µ’’ in the frequency range 10 MHz to 1 GHz were measured in this study. The results showed that the highest μ΄ is 5.890 obtained from 1100 °C

Optimizing Bi2O3 and TiO2 to achieve the maximum non-linear electrical property of ZnO low voltage varistor

In fabrication of ZnO-based low voltage varistor, Bi2O3 and TiO2 have been used as former and grain growth enhancer factors respectively. Therefore, the molar ratio of the factors is quit important in the fabrication. In this paper, modeling and optimization of Bi2O3 and TiO2 was carried out by response surface methodology to achieve maximized electrical properties. The fabrication was planned by central composite design using two variables and one response. To obtain actual responses, the design was performed in laboratory by the conventional methods of ceramics fabrication. The actual responses were fitted into a valid second order algebraic polynomial equation. Then the quadratic model was suggested by response surface methodology. The model was validated by analysis of variance which provided several evidences such as high F-value (153.6), very low P-value (<0.0001), adjusted R-squared (0.985) and predicted R-squared (0.947). Moreover, the lack of fit was not significant which means the model was significant

Structural and magnetic properties of aluminum substituted yttrium iron garnet via sol-gel synthesis

Aluminum-substituted yttrium iron garnet (Al-YIG) powders was synthesize by using sol-gel citrate nitrate combustion technique with different doping concentration (x = 0.4, 0.6 and 1.0). The Y3-x Alx Fe5O12 samples were analyse of phase, structural and hysteresis by using X-ray diffraction (XRD), Fourier transform infra-red (FTIR) and Vibrating Sample Magnetometer (VSM).The powder resulted a single phase nanostructured garnet was formed. Room temperature saturation magnetization Ms and coercivity of Al-YIG powders decreased as a function of increasing Al content. The samples has a room temperature Ms of 9.2 emu/g and decreased to 1.5 emu/g. Coercivity Hc value decreases from 71.7 G to 51.4 G

Annealing study of α-Fe2O3 nanoparticles steel-waste based: microstructure and magnetic behavior

The interest of this paper is to show the influence of annealing process on magnetic properties and microstructure of -Fe2O3 derived from steel waste product (mill scales). The mill scales flakes were wet ball milling for several hours to form a fine powder. The mill scales powder was purified by using magnetic separation to isolate the magnetic and non magnetic particles. The method was continue for Curie temperature separation technique. The purified powder was annealed at 400/450/500 and 550 °C at 6 oC/mins to form hematite, -Fe2O3. The annealed powders were milled for several hours by using mechanical alloying. Annealing at varied temperatures produced α-Fe2O3 nanopowders with average crystallite size 18.1 nm to 28.6 nm. Phase transformation occurred directly by annealing in air, conversion of FeO and Fe3O4 phase to form α-Fe2O3. The correlation between the magnetic properties and microstructure, of the sintered powders at 1200 oC enables to obtain microphase of α-Fe2O3 and Fe3O4 with different particle size and magnetic properties. The resultant α-Fe2O3 nanopowders are ferromagnetic with moderate coercivities

Composition and magnetic properties of aluminium substituted yttrium iron garnet waste mill scales derived via mechanical alloying technique

This paper presents the effects of aluminium substitution on sample composition, density and magnetic properties of yttrium iron garnet, Y3Fe5O12 (YIG). Mill scales, in a form of flakes was obtained from the steel industry in Malaysia. The mill scales was purified to produce high purity hematite, Fe2O3. The mill scales derived Fe2O3 were used as raw material to prepare the aluminum substituted yttrium iron garnet Y3Fe(5-x) Al(x) O12 (Al-YIG) with variation compositional x = 0.0, 0.5, 1.0, 1.5 and 2.0 using mechanical alloying technique. X-ray fluorescence (XRF) was used to investigate the percentage compositions of the raw mill scales. The magnetic hysteresis of sample were investigate by using B-H tracer (MATS). Density of the Al-YIG bulk samples was found to decrease with increasing xAl2O3 content. The saturation magnetization Ms also shows a decrease with increase xAl2O3 content. The maximum saturation magnetization Ms and coercivity Hc was found at 310 G and 14.98 Oe, respectively. With increase xAl2O3 to 2.0%, the Ms and Hc were reduced to 29.35 G and 3.15 Oe, respectively