Effect of substrate temperature on structural, static and dynamic magnetic properties of FeSi/(001) MgO films

FeSi films with different substrate temperature (Ts) were deposited on MgO (001) substrates by a radio frequency magnetron sputtering. During the change of crystal structure from amorphous epitaxial state, magnetic anisotropy experienced three stages: dominant uniaxial magnetic anisotropy (Ts < 400 ℃) and enhanced cubic magnetocrystalline anisotropy (400 ℃ £ Ts £ 600 ℃) and weak cubic magnetocrystalline anisotropy (Ts = 700 ℃ and 800 ℃). In addition, resonance frequency ƒr firstly decreases, then reaches the maximum value, and finally disappears due to the large coercivity field. These results demonstrate the correlation between the structure, static, dynamic magnetic properties of FeSi films, and provide an effective method to prepare soft films with deterministic uniaxial or cubic magnetic anisotropy for practical application.

The High Coercivity Field in Chemically Bonded WSe2/MoSe2 Powder

We studied the magnetic properties of WSe2/MoSe2 powder. The coercivity field reaches 2600 Oe at 5 K, 4233 Oe at 100 K and 1300 Oe at 300 K. These are the highest values reported for two-dimensional transition metal dichalcogenides. This study is different from the widely reported vacancy and zigzag structure-induced ferromagnetism studies. Importantly, a Raman peak red shift was observed, and that supports the chemical bonding at the interface between WSe2 and MoSe2. The large coercivity field originates from the chemical bonding-induced structural distortion at the interface between WSe2 and MoSe2.

Effect of La-Substituted Barium Hexaferrite on the Structural Characteristics and Magnetic Properties for Microwave Absorbing Material

Ba1-xLaxFe12O19 with ion substitution La3+ (x = 0 – 0.7) has been produced via the mechanical milling technique of the solid reaction method. Considering that Ba1-xLaxFe12O19 is expected to be used as a microwave absorbent, it is necessary to characterize its structural and magnetic features. The refinement results of the X-ray diffraction (XRD) data show that a single-phase hexagonal structure (space group P63/mmc) is obtained for x = 0 and x = 1, while for the composition of x 0.1 is multiphase. The lattice parameters and crystal volume decreased, whereas the lattice strain was found to advance with increasing La substitution in the sample. For x = 0.1, the crystallite size is constant while the lattice strain increases. Employing a scanning electron microscope (SEM), the observation of particle morphology shows that the single-phase (x = 0 and x = 0.1) has a comparably unvarying particle size circulation, while for x 0.1, different particle shapes and sizes are found. The saturation magnetization raises while the coercivity field reduces due to the substitution of La for x = 0.1. Furthermore, for x 0.1, the saturation magnetization decreases while the coercivity field increases.

The effect of stress on the magnetic properties of low bandwidth manganites

The low bandwidth Pr0.9Ca0.1MnO3 (PCMO) thin films prepared by sol-gel method were suffered tensile and compressive stress grown on SrTiO3 and LaAlO3 substrates. The hysteresis loops at different temperatures show that the coercivity field with tensile stress is larger due to the much stronger pinning potential of ferromagnetism motion. The temperature dependence of the ZFC and FC magnetizations indicates that the stress significantly affects the ferromagnetic (FM) and antiferromagnetic (AFM) transition temperature of PCMO, and the Curie temperature (TC) decreases with tensile stress. The films show strong anisotropy properties that the magnetization increases much faster with the magnetic field when H⊥c, but the coercive field and saturation magnetization do not change significantly. In addition, the persistent photoinduced magnetization is investigated, and significant improvement of the ferromagnetic ordering was observed in low temperature.

Development of Nd-Fe-B rubber-bonded permanent magnets: Magnetic and mechanical characterization

In this work, the mechanical and magnetic properties of a new Nd-Fe-B filled Hydrogenated nitrile butadiene rubber (HNBR) mixtures are investigated. The mass fraction of the magnetic particles was specifically modified to determine the magnetic and mechanical property trends. The particles have isotropic properties, so no magnetic fields are used for particle orientation during vulcanization. Increasing the filler concentration of the Nd-Fe-B powder leads to a reduction of the tensile strength and an increase in density, elongation at break and hardness of the mixture. The vulcanization times of the compound at different vulcanization levels show hardly any differences by changing the degree of filling. By increasing the filler content from 67% to 80%, the viscosity of the compound increases by a factor of 1.41, which has a strong influence on the processability of the material. Increasing the filling degree of the powder leads to an increase in remanence and the coercivity field strength HcB. For the coercivity field strength HcJ, hardly any change is detected due to the variation in filling level.

THE EFFECT OF COBALT CONTENT ON MAGNETIC PROPERTIES OF CoFe ALLOYS

Hard Disk Drive (HDD) as a data storage device when operated with high temperatures (around 66oC), its function will be constrained. The CoFe alloys have a large coercivity field and can be patterned in very small sizes that are suitable for HDD devices. In this study, Co1-x Fex cube alloy was used (x = 0.25; 0.30; 0.50; 0.75). Samples were treated with temperature changes to get the Curie temperature. The coercivity field value is obtained by giving the external field and temperature below Curie temperature and also above Curie temperature to the samples. The VAMPIRE software is a micromagnetic simulation program based on atomistic models. The results showed that Curie’s temperature decreased when Co content increased. The composition of Co0.25 Fe0.75 has the highest Curie temperature that is equal to 1075 K. The temperature Curie is not affected by the size of the cube. When the sample is given a temperature rise below the Curie temperature, the value of the coercivity field decreases. The value of the coercivity field is very difficult to determine when the temperature used is above the Curie temperature. The percentage of composition does not affect the coercivity field value. Therefore, cube-shaped CoFe material is very suitable for use as a material data storage device operated at temperatures below the Curie.

Effects of NaOH Concentration and Temperature on Microstructures and Magnetic Properties of Bismuth Ferrite (BiFeO3) Nanoparticles Synthesized by Coprecipitation Method

Bismuth ferrite (BiFeO3) nanoparticles has been synthesized by coprecipitation method with various NaOH concentration (4, 6, 8, and 10 M) and temperature (RT, 60, 80, and 100 C). X-ray diffraction patterns showed the emergence of Bi(OH)3 and Bi25FeO40 structures with crystallite size in the range of 15.1 nm to 35.6 nm. The particles sample was agglomerated. Hysterisis loop showed the linear M–H loops behaviour with no magnetization saturation in 15 kOe maximum field applied which indicates the antiferromagnetic properties. The coercivity field tends to increase by the increasing of the NaOH concentration and synthesis temperature. In addition, the annealing treatment could leads the increasing of coercivity fields while decreasing the magnetization of BFO sampel.

Analysis of Crystallography Structure and Magnetic Properties of Microwave Absorbing Material Ba0.6Sr0.4Fe12-3xZn2xTixO19 (X = 0, 0.2, 0.4, and 0.6)

The synthesis and characterization of the Ba0.6Sr0.4Fe12-3xZn2xTixO19 microwave material with x = 0, 0.2, 0.4, and 0.6 has been successfully carried out. Samples were processed with the solid reaction method through milling at seven hundred revolutions per minute for five hours. X-ray diffraction was used to characterize the phase formation and crystal structure. Scanning electron microscopy was used to see the shape and size of particles, while the vibrating sample magnetometer was used to measure magnetic quantities, which are: the coercivity field and magnetic saturation. All samples have a hexagonal structure, for samples x = 0 and 0.2 have a single phase, while for samples x = 0.4 and 0.6 other phases are detected. The shape of the particles are heterogeneous, with size ranging from 10-25 μm. All samples were not saturated even until the external magnetic field reaches 1 T. As the value of x increases, the magnetization will decrease. Samples substituted by Zn and Ti (x ≠ 0) have higher coercivity field values when compared to sample without substitution (x = 0).

Preparation of Local Raw Material for α-Fe2O3 Nanoparticles Powder from Mineral Extraction of Iron Sand

Synthesis and characterization of α-Fe2O3 nanoparticles were obtained from extraction of ilmenite iron sand with coprecipitation method and to obtain α-Fe2O3 nanoparticles, high energy milling (HEM) was used. Surface morphology and identification of the elements contained in the sample were analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). For phase analysis and crystal structure, X-ray diffractometer (XRD) was used. Moreover a vibrating magnetometer sample (VSM) was used to characterize its magnetic properties, while tunneling electron microscopy (TEM) was used for particle size characterization. Ilmenite-type iron sand has a diverse particle shape with a size of more than 100 μm with ilmenite (FeTiO3) mineral content of about 64.7%. The results of extraction using coprecipitation method with sintering 750 °C, obtained hematite α-Fe2O3 material which has not been saturated to an external magnetic field of 1 tesla, the magnetic remanent value (Mr) is about 0.8 emu/g and the coercivity field value is Hc around 773 Oe. The average size of hematite α-Fe2O3 particles after being milled 50 hours is between 15-30 nm with a cube-like shape.

KARAKTERISASI DAN SIFAT KEMAGNETAN PASIR BESI EKSTRAKSI ASAL PANTAI BETAF SARMI, PAPUA

Characterization and magnetic behavior test of extracted iron sand from Betaf beach of Sarmi Papua was studied. The purpose of the recearch was to determine minerals content, phase of iron compound, and magnetic behavior of extracted iron sand from Betaf beach of Sarmi Papua were caculate using XRF, XRD and VSM. The result showed that extrated iron sand was contained 43,81% of Iron (Fe), 25,75% of Silika (Si) and 30,44 % others. The XRD pattern showed that the highest peak was magnetite (Fe3O4) at 2= 35,65o. The histerisis curve of VSM showed that extracted iron sand from Betaf beach of Sarmi Papua was superparamagnetic material where maximum saturation magnetization (Ms) value of 4,54 emu/gr, remanen magnetization (Mr) value of 0,371 emu/gr and coercivity field (Hc) value of 208 Oe.