Electrical, magnetic and microwave absorption properties of multiferroic NiFe₂O₄-BaTiO₃ nanocomposites

Abstract

Multiferroic nanocomposites of xNiFe2O4/(1-x)BaTiO3 (x = 0, 0.1, 0.2, 0.3, and 0.4) (denoted as NFO-BTO) with the particle size about of 70 nm were prepared by the high energy mechanical milling combined with the thermal annealing methods. The X-ray diffraction patterns show a presence of NiFe2O4 (NFO) and BaTiO3 (BTO) phases. The values of the characteristic parameters of nanocomposites such as the coercive field (E c), the residual polarization (P r), the remanent magnetization (M r), the saturation magnetization (M s), and the coercive force (H c) increase gradually with an increase in NFO concentration. For an applied electric field below 10 kV/cm, the values P r and E c are found to be 0.004-0.038 µC/cm2 and 0.7-2.0 kV/cm, corresponding x = 0.1-0.4, respectively. Changes in electrical and magnetic properties of composites depend heavily on the NFO content, which will be studied specifically. Additionally, the ability to absorb microwave at room temperature of a representative sample with x = 0.3 mixed in acrylic paint (denoted as NFO-BTO-AP) in a frequency range of f = 12-18 GHz has also been investigated. It shows a large negative reflection loss (RL) with RL = -39.8 dB occurring at around 16.8 GHz corresponding to the absorptivity of over 99.9% for an absorbing layer with thickness of 5.5 mm. This suggests that NFO-BTO nanocomposites could be considered as a potential material in the field of absorbing and shielding electromagnetic waves.

Enhanced ferroelectric and ferromagnetic properties of xNiFe2O4/(1–x)Ba0.94Ca0.06Ti0.975Zr0.025O3 nanocomposites

“…This feature is consistent with published reports on BTO-based materials [39][40][41]. BTO is a ferroelectric material with a narrow and curved P(E) hysteresis loop [23]. Co-doping of Ca and Zr to the A and B sites of BTO slightly improved the ferroelectric properties, as shown in figure 6(a).…”

“…The comparison of magnetic and electrical properties of BTO/NFO-based composites is presented in table 1. Considering ferroelectric property, BCTZ/NFO composites in this work had higher P max , P r , and E c values than xNiFe 2 O 4 /(1-x)BaTiO 3 prepared by the same method [23]. This could be attributed to the difference in particle shape and size.…”

“…The diffraction peaks of the NFO phase were marked by open triangle symbols, whereas solid triangle symbols were for the BCTZ phase. The x = 0 sample showed only diffraction peaks of the BCTZ phase, which were crystallised into a tetragonal structure with the Pbmm space group [23]. The peak intensity of the NFO phase was increased with respect to the increase in NFO concentration in the composites.…”

“…The peak intensity of the NFO phase was increased with respect to the increase in NFO concentration in the composites. With x = 0.1-0.4, the diffraction peaks of the NFO phase could be observed, which crystallised into a cubic spinel structure with the Fd-3m space group [23]. The lattice parameters of the x = 0 sample (only BCTZ phase) were calculated using the Bragg law equation, which showed the values of a = 4.026 Å and c = 4.063 Å.…”

“…Multiferroic properties of BCTZ/NFO nanocomposites and some BTO/NFO-based composites with different compositions and fractions of ferroelectric and ferromagnetic phases.Magnetisation obtained at the highest external applied field of 30 kOe.Considering ferromagnetic properties, the BCTZ/NFO nanocomposites of this work significantly enhanced magnetic properties by improving the M s values compared to xNiFe 2 O 4 /(1-x)BaTiO 3 composites prepared by solid-state reaction[48] and high-energy ball milling[23] methods. Not only composites of a pure phase of NFO and BTO but also BCTZ/NFO composites in this work had higher M s values compared to composites of xNiFe 2 O 4 /(1-x)Ba 0.9 Sr 0.1 Ti 0.9 Zr 0.1 O 3 prepared by the mechanochemical activation technique[26] and xCoFe 2 O 4 /(1-x)Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 composites fabricated by the sol-gel method[49].…”