Кристаллохимия и магнитные свойства гексаферрита BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- при гетеровалентном замещении железа цирконием

Samples of BaFe12O19 M-type barium hexaferrite with partial iron substitution by zirconium ions (concentration up to 10 at.%) have been synthesized and investigated. Studies of crystal features, phase composition, and magnetic properties were carried out using X-ray diffraction, Mössbauer spectroscopy, and VSM respectively. The presence of limited heterovalent isomorphism by the 2Fe3+ → Zr4+ + Fe2+ mechanism was shown. The limit of heterovalent isomorphic substitution by zirconium ions in barium hexaferrite (x = 0.6) was established. It was noted that additional sextets in the Mössbauer spectra of barium hexaferrite can be formed during the localization of Zr4+ ions predominantly in the 12k and 4f2 positions due to the frustration of the magnetic structure. The correlation between the chemical composition (concentration of zirconium ions), impurity phase formation, the peculiarities of the distribution of substituents over oxygen coordination, and the magnetic properties was established.

Synthesis and characterization of permanent magnetic oxide system Ba1-x-yLaxCeyFe12O19 system doped with La-Ce metal using wet mechanical milling method

The development of permanent magnet-based rare earth metals becomes a serious problem if the raw materials are difficult to find. The solution chosen is to utilize an oxide-based permanent magnet with little substitution of rare earth metals. In this study presented a permanent magnetic synthesis of barium hexaferrite-based oxides that were doped with La and Ce atoms. The synthesis of this material uses the wet mechanical milling technique to obtain the single phase permanent magnet system Ba1-x-yLaxCeyFe12O19 (x = 0, 0.02, 0.04 and y = 0. 0.05, 0.1). The precursor is weighed according to stoichiometric composition and is milled for 5 hours then compressed at a pressure of 7000 Psi. Sintering temperature for the formation of the barium hexaferrite phase at 1200oC for 2 hours. All samples after sintering were characterized using XRD and EDS. A single phase is obtained on all sample compositions with a hexagonal P63/mmc structure and is supported by elemental analysis data that each substituted sample contains elements La and Ce. Lattice parameters a, b, and c appear to decrease with increasing concentrations of La and Ce doping ions with a ratio of c/a in the range of 3.93-3.94.

Barium hexaferrite/muscovite heteroepitaxy with mechanically robust perpendicular magnetic anisotropy

Recent advances in the design and development of magnetic storage devices have led to an enormous interest in materials with perpendicular magnetic anisotropy (PMA) property. The past decade has witnessed a huge growth in the development of flexible devices such as displays, circuit boards, batteries, memories, etc. since they have gradually made an impact on people’s lives. Thus, the integration of PMA materials with flexible substrates can benefit the development of flexible magnetic devices. In this study, we developed a heteroepitaxy of BaFe12O19 (BaM)/muscovite which displays both mechanical flexibility and PMA property. The particular PMA property was characterized by vibrating sample magnetometer, magnetic force microscopy, and x-ray absorption spectroscopy. To quantify the PMA property of the system, the intrinsic magnetic anisotropy energy density of ~2.83 Merg cm−3 was obtained. Furthermore, the heterostructure exhibits robust PMA property against severe mechanical bending. The findings of this study on the BaM/muscovite heteroepitaxy have several important implications for research in next-generation flexible magnetic recording devices and actuators.

In-Plane Current Induced Nonlinear Magnetoelectric Effects In Single Crystal Films of Barium Hexaferrite

This report is on the observation and analysis of nonlinear magnetoelectric effects (NLME) for in-plane currents perpendicularly to the hexagonal axis in single crystals and liquid phase epitaxy grown thin films of barium hexaferrite. Measurements involved tuning of ferromagnetic resonance (FMR) at 56-58 GHz in the multidomain and single domain states in the ferrite by applying a current. Data on the shift in the resonance frequency with input electric power was utilized to estimate the variations in the magnetic parameter that showed a linear dependence on the input electric power. The NLME tensor coefficients were determined form the estimated changes in the magnetization and uniaxial anisotropy field. The estimated NLME coefficients for in-plane currents are shown to be much higher than for currents flowing along the hexagonal axis. Although the frequency shift of FMR was higher for the single domain resonance, the multi-domain configuration is preferable for device applications since it eliminates the need for a large bias magnetic field. Thus, multidomain resonance with current in the basal plane is favorable for use in electrically tunable miniature, ferrite microwave signal processing devices requiring low operating power.