Ce–Dy substituted barium hexaferrite nanoparticles with large coercivity for permanent magnet and microwave absorber application

Abstract

M-type barium hexaferrites (BaM) with the substitution of Ce–Dy ions were synthesized using the sol-gel auto-ignition method. The prepared materials were explored for their application as a permanent magnet and microwave absorbing material. The structural properties, phase evaluation, micro-strain, morphological analysis, magnetic behaviour, microwave absorbing properties and optical properties were studied by employing various techniques. The structural parameters and phase identification obtained by Rietveld refinement confirmed the formation of an M-type hexaferrite structure for pure BaM, whereas Ce–Dy substitution induced secondary phases of cubic CeO2 and ortho DyFeO3. Crystallite size obtained from Williamson–Hall plots increased from 27.1 nm to 30.8 nm with the introduction of Ce–Dy ions in BaM. The nanocrystalline nature of the prepared samples was confirmed using scanning and transmission electron microscopy techniques. Fourier transform infrared spectra of all the samples were recorded in the wavenumber range of 400–4000 cm−1 and also supported the x-ray diffraction findings by confirming the formation of samples with hexaferrite structures. Coercivity of the BaM hexaferrites improved from 4430 to 5721 Oe with the Ce–Dy substitution. A Ce–Dy substituted BaM hexaferrite sample of 3 mm thickness showed a maximum reflection loss of −16.3 dB around 16.7 GHz. Permittivity and permeability studies were carried out to understand the microwave absorption behaviour.

Excellent Microwave Absorbing Properties of Nd3+‐Doped Ni–Zn Ferrite/PANI Nanocomposite for Ku Band

“…The RL was calculated from complex permittivity and permeability data. The RL is a function of the coefficient of reflection of wave and can be represented by the following equation [ 11,15 ] where Z 0 is the impedance of free space, is the impedance of the absorber, and are the complex relative permittivity and permeability of free space, respectively, f is the EM wave frequency, t is the thickness of the absorber, c is the velocity of microwaves in free space, and μ r and ε r are the measured relative complex permeability and complex permittivity, respectively.…”

“…The RL was calculated from complex permittivity and permeability data. The RL is a function of the coefficient of reflection of wave and can be represented by the following equation [11,15] Reflection loss ¼ 20 log…”

“…[13,14] Therefore in the recent years, high-frequency electromagnetic wave absorbing materials attracted the researcher. [15][16][17] In aerospace science, the development of the lightweight absorbing materials in a broad range of frequencies is an essential part of the electromagnetic wave absorption technology to minimize the microwave reflection. [18] An excellent EAM required considerable conductive properties, high magnetic loss, and dielectric properties to achieve the requirements for large bandwidth and maximum absorbing capability.…”

Effect of cation distribution on structural and mechanical properties of Y3+ substituted Co-Zn spinel ferrites nanoparticles.

“…Magnetic oxides, in particular spinel ferrites with nano-size dimension have been comprehensively studied due their distinctive physical properties such as high magnetocrystalline anisotropy, high coercivity, very high chemical and mechanical stability, moderated saturation magnetization, low losses of eddy currents and low conductivity [1][2][3][4][5]. Such unique properties of nano-ferrites make them suitable for various medical and technological applications like waste water treatment [6], treatment for hyperthermia [7], drug delivery carriers [8], magnetic, humidity and biosensors [9][10], microwave devices, high density data storage devices, magnetic recording media, computer memory chips and high frequency devices [11][12]. Even after several years of their discovery, the unique combination of magnetic and electrical properties, ferrites have drawn much attention to the scientific society and still growing the interest [13].…”

Williamson-Hall and Size-strain plot based micro-structural analysis and evaluation of elastic properties of Dy3+ substituted Co-Zn nano-spinels

“…These nano-ferrites also applicable in biomedical applications such as hyperthermia treatments, magnetic carrier in drug delivery, biological dealings etc. [6][7][8]. They are also usable in gas/humidity sensors, waste water processing, catalysis process etc.…”