Multiferroic properties and structural features of M-type Al-substituted barium hexaferrites (original) (raw)
Related papers
Journal of Electronic Materials, 2019
Ti-doped M-type barium hexaferrite compounds (BaFe 12Àx Ti x O 19 , x = 0-0.8) were prepared in single phase form. The lattice constant c is found to increase systematically with the concentration. Temperature variation of the magnetization measurement shows that all the samples exhibit ferrimagnetic transition with a systematic decrease in transition temperatures (T c) from 720 K for x = 0-608 K for x = 0.8. The analysis of impedance spectra shows the deviation of relaxation process from the ideal Debye type and the relaxation of charge carriers across grains and grain boundaries is clearly elucidated by considering an equivalent electrical circuit. The analysis of conductivity data measured at different temperatures reveals that the conduction activation energy (E c) decreases as the Ti concentration is increased. The present study demonstrates that Ti doped M-type barium hexaferrite compounds exhibit a moderate value of saturation magnetization and a low value of coercivity.
Enhanced Magnetic Properties of Barium Hexaferrite
Journal of Electronic Materials, 2020
Samples having the composition BaFe 12À2x Co x Sm x O 19 (x = 0.0, 0.2, 0.4, 0.6) are prepared by a WOWS (without water and surfactants) sol-gel technique, and the structural, morphological, and AC and DC electrical and magnetic properties of the samples are investigated. The phase formation of M-type hexaferrite is studied by using indexed x-ray diffraction patterns. Scanning electron microscopy images show that the particle size of the synthesized nanopowder varies from 295 nm to 440 nm. The dielectric constant (e¢) exhibits a decreasing trend while the dielectric loss (tan d) increases with increased doping. DC electrical resistivity (q DC) is investigated in a temperature range of 373-673 K and indicates an increasing trend with doping. The magnetic hysteresis loops reveal an increase in saturation magnetization (M s) and remanence (M r), and a decrease in coercivity (H c), with the increase in doping content.
Investigation of magnetic, dielectric and electrical properties of Ba-hexaferrites
Ba-hexaferrites of composition (BaO)1−x (La2O3)x 5.7 Fe2O3, where x = 0.00, 0.04, 0.08 and BaO 5.7 Fe2O3 + [0.7 wt% CaO + 0.3 wt% SiO2] were prepared by standard double sintering ceramic technology using magnetite from Cox’s Bazar beach sand, Bangladesh. In this work, magnetic, dielectric and electrical properties of Ba-hexaferrites with and without additives have been reported. Measurements of permeability, loss factor, quality factor (Q-factor), resistivity and dielectric constant of the synthesized samples have been carried out. Permeability remains unaltered in the observed frequency range. The loss factor increases with the increase in temperature and additives as well. It has been observed that the loss factor decreases with the increase in frequency. The Q-factor decreases with the increase in temperature and increases with the increase in frequency. The dielectric constant decreases with the increase in frequency. The ac resistivity of Ba-hexaferrites increases with the increase in additive contents.
Journal of Alloys and Compounds, 2014
Large single crystals of aluminum-substituted M-type barium hexaferrite BaFe 12-x Al x O 19 were obtained from carbonate flux. The Al content in the crystals can be controlled via the Al content of the flux up to x = 1.1 according to single crystal X-ray structure refinements. Al shows a distinct preference to substitute Fe on crystallographic sites with high coordination numbers by oxygen atoms, whereas no significant amounts of Al can be found on a tetrahedrally coordinated site. An increasing amount of the aluminum dopant results in a monotonous reduction of the Curie temperature from 440 to 415 °C and the saturation magnetization at room temperature from 68 to 57 emu/g for single crystal and from 61 to 53 emu/g for powder samples.
Magnetic Properties and Hyperfine Interactions in M-Type BaFe12-2xMoxZnxO19 Hexaferrites
Journal of Applied Mathematics and Physics, 2014
A series of M-Type barium hexaferrites with the general composition BaFe12-2xMoxZnxO19 were synthesized at 1100˚C by a simple wet chemical mixture route. The properties of the prepared samples were examined by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and Mössbauer spectroscopy. The diffraction patterns for all samples were found to agree well with the standard pattern of BaFe12O19 hexaferrite with no extraneous diffraction peaks. The products formed as well crystallized hexagonal platelet-like particles while the EDS measurements revealed the stoichiometric cationic ratios of the prepared samples. The spectral variations elucidated by Mössbauer spectroscopy were utilized to determine the different cation preferential site occupations as a function of x. Finally, the saturation magnetizations, magnetic anisotropies, and the anisotropy fields, determined from the magnetic measurements, showed consistency with the relative subspectral Mössbauer intensities and the single ion model for the anisotropy constant.
Effect of Grain Size on Electric and Magnetic Properties of Barium Hexaferrite (BaFe12O19
2016
Polycrystalline Barium hexaferrite (BaFe12O19) having variable grain sizes were prepared by auto-combustion and solid state technique. SEM micrograph shows the variation of grain size (from nano range to bulk) of the system prepared at different temperatures. For this work electric transport (in the frequency range 100Hz to 1Mz) and magnetic study (M-H loop) carried out at room temperature. From the electric study it was found that, resistivity of the system varies inversely with grain size, however saturation magnetization (Ms) varies directly with grain size. In our report we were attempted to resolve the relation between grain size with electric and magnetic properties of the studied system.
Effect of treatment conditions on structure and magnetodielectric properties of barium hexaferrites
Journal of Magnetism and Magnetic Materials, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Polarization origin and iron positions in indium doped barium hexaferrites
Ceramics International, 2017
M-type hexaferrirte BaFe 12-x In x O 19 (x = 0.1, 1.2) samples were investigated by high resolution neutron powder diffraction and vibration sample magnetometry in a wide temperature range of 4-730 K. Structural and magnetic parameters were determined including the unit cell parameters, ionic coordinates, thermal isotropic factors, occupation positions, bond lengths and bond angles, microstrain values and magnetic moments. In 3+ cations may be located only in the Fe1-2a and Fe2-2b crystallographic positions with equal probability for the x = 0.1 sample. At x = 1.2 about half of In 3+ cations occupy the Fe5-12k positions whilst the other half are equiprobably located in the Fe1-2a and Fe2-2b positions. The spontaneous polarization was observed for these compositions at 300 K. The influence of structural parameters on the temperature behavior of Fe 3+ (i)-O 2-Fe 3+ (j) (i, j = 1, 2, 3, 4, 5) indirect superexchange interactions was established. With the substitution level increase the superexchange interactions between the magnetic positions inside and outside the sublattices are broken which leads to a decrease in the value of the corresponding magnetic moments.
Synthesis and Magnetic Properties of Barium Hexaferrite Powders Using Organic Acid Precursor Method
Journal of Superconductivity and Novel Magnetism, 2012
An investigation of the synthesis of BaFe 12 O 19 powders by the organic acid precursor method is reported by acidic and neutral media. X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM) are utilized to study the effect of organic precursor type and annealing temperature on the crystal structure, crystallite size, microstructure and magnetic properties of the formed powders. The XRD analysis showed that the crystalline BaFe 12 O 19 phase was obtained at 1200°C for 2 h using different carboxylic acids in acidic medium. However, pure BaFe 12 O 19 was achieved at low annealing temperature 1000°C in neutral medium. SEM micrographs showed that the particles were strongly influenced by type of carboxylic acid and the annealing temperature. VSM study indicated that the saturation magnetization was increased with increasing annealing temperature to 1200°C as the result of formation of single barium hexaferrites phase. High saturation magnetization (M s = 66.5 emu/g) was achieved for the formed powders in neutral medium using tartaric acid as organic precursor. Wide coercivities of the formed powders (H c = 259-5114 Oe) were obtained.
Current Applied Physics, 2019
We have investigated the correlation between structural and magnetic properties of M-type BaFe 12 O 19 thin films (~ 1.4 m ) with Co-Ti (magnetic/non-magnetic) and Co-Ni(magnetic/magnetic) substitution, as BaFe 12-2x Co x Ti x O 19 and BaFe 12-2x Co x Ni x O 19 (0 ≤ x ≤ 1). With structural properties sensitively related to the magnetic properties, where ferro-ferri phase transition is involved, it has been found that magnetic properties can be substantially controlled by substitution concentration. .