Investigation of magnetoelectric effect in lead free K0.5Na0.5NbO3-BaFe12O19 novel composite system

Abstract

Lead-free magnetoelectric composites (1 ̶ x)K 0.5 Na 0.5 NbO 3 -(x)BaFe 12 O 19 (x = 30, 40, and 50 wt%) are synthesized using solid state reaction method. X-ray diffraction (XRD) patterns confirm formation of diphase composites. Field emission scanning electron microscopy (FE-SEM) gives information about grain size, connectivity, and microstructure of constituent phases. Dielectric parameters of composite samples are studied as a function of temperature and the transition temperatures corresponding to both the constituent phases are observed in the composite samples. Dielectric constant has been found to decrease with addition of ferrite. Room temperature multiferroic behaviour has been confirmed using P-E and M-H hysteresis loops and magnetoelectric measurement. Polarization is found to decrease; however, magnetization increases with ferrite weight percentage. The highest α ME of 4.08 mV/(cm⋅Oe) is obtained for x = 30 wt% composite and it is realized that ferrite content significantly affects magnetoelectric behaviour.devices [6]. Large scale applications of ME composites given their higher ME coupling than that of single phase materials make them a beguiling research concern. ME coupling in the composites is basically a product property arising due to combination of magnetostrictive (magnetic/mechanical) phenomena in ferrite and piezoelectric (meachanical/electrical) phenomena of ferroelectric phases [7]. ) x [12], etc. are studied in the previous years. Generally for fabrication of good ME composites, the piezoelectric and magnetostrictive coefficients of constituent ferroelectric and ferrite phases should be high respectively. Furthermore high resistivity is equally desirable for avoiding leakage of charges [13]. K 0.5 Na 0.5 NbO 3 (KNN) has been considered as a bright prospect as a ferroelectric constituent for fabrication of lead-free ME composites. KNN exhibits reasonably well ferroelectric, piezoelectric, and dielectric characteristics. It exhibits high piezoelectric charge constant (d 33 ≈ 80-416 pC/N) and a high planar coupling coefficient (k P ≈ 45%) [14][15][16]. It also exhibits large remnant polarization and coercive field (P r = 21 μC/cm 2 , E c = 7.2 kV/cm, P r = 20 μC/cm 2 , and E c = 8 kV/cm) [14,17]. The M-type hexaferrites are widely studied materials due to their unique physical properties. The hexagonal ferrites including BaFe 12 O 19 (BHF) have magneto-plumbite structure. The crystal structure of BHF and diamagnetically doped BHF may be described by two space group viz. P6 3 /mmc (No. 194) and P6 3 mc (No. 186). The latter one is a non-centrosymmetric space group and is generally used to describe the crystal structure in order to explain the existence of non-zero spontaneous polarization [18,19]. These ferrites are usually termed as hard ferrites because of their high electrical resistivity, saturation magnetization, coercivity, and mechanical hardness [20]. At higher frequencies, hexaferrites have low-eddy current losses and high resistivity as compared to other magnetic materials [21]. ...

Development of novel piezo-ionic/magnetostrictive composites for energy generation systems

“…This trend is expected to continue until frequencies close to 100 MHz, where the slowest and largest relaxation processes of the ionic liquid appear [41,49]. The MI coefficient obtained values are comparable, and even higher, than others obtained with recent composites based on multiaxial molecular-ionic ferroelectric/magnetostrictive materials [28] or ME composites [50,51], where values up to 186 mV cm −1 .Oe have been reported. Thus, our flexible and low cost developed structures based on non-polarized piezo-ionic/magnetostrictive materials open new perspectives in the development of advanced and functional composites for novel energy generation devices.…”

A neutron diffraction investigation of high valent doped barium ferrite with wideband tunable microwave absorption

“…BaM-based cationic substitutions for Fe 3+ are used to modify the dielectric and magnetic parameters, which play an important role in RL calculation. The substitutions for Fe 3+ of BaM-based can be divided into two main approaches: covalent cation substitution, such as Ga 3+ , In 3+ ; and Er 3+ and hetervalent cationic combination, such as Co 2+ -Ti 4+ , Co 2+ -Zr 4+ , and Ni 2+ -Ti 4+ [22][23][24][25][26]. However, recent studies have shown that the introduction of high-valence ions destroys the valence state equilibrium of barium ferrite, resulting in multiple absorption peaks, which can increase the bandwidth of electromagnetic wave absorption of the material [27][28][29].…”

Component fraction effect on microstructure and properties of CoFe2O4−K0.5Na0.5NbO3 composites

“…3 So far, there were only limited numbers of studies on the CFO−KNN particulate composites, although pure or doped KNN and CFO have each been used frequently for making ME composites with other counterparts. 3,6,[11][12][13][14][15] Recently, computer simulation revealed that the composites made of KNN-based ferroelectrics and CFO-based ferrimagnets may potentially have high ME coefficients. 15…”