Phase switching phenomenon in magnetoelectric laminate polymer composites: Experiments and modeling

Development of magnetoelectric CoFe2O4 /poly(vinylidene fluoride) microspheres

“…In both cases ill-crystallized region arises with lower melting temperature due to the larger energy of the imperfect structures. The degree of crystallinity values (Figure 4b) are in good agreement with the ones obtained in PVDF processed by similar procedures 36 . Additionally, the overall lower degree of crystallinity is slightly lower when the fillers are present in the polymer matrix, which is attributed to hindered crystallization due to the presence of the fillers, which can act as nucleation centers for crystallization, but also hinder spherulite growth 31,35 .…”

Magnetoelectric coupling in Fe 3 O 4 /P(VDF-TrFE) nanocomposites

“…In this way, two main types of ME composites have been elaborated and studied: the particulate composites, which correspond to magnetic particles incorporated in a piezoelectric matrix [7][8][9][10][11] and the layered (laminate) magnetostrictive/piezoelectric composites, made of a 3 superposition of magnetic (magnetostrictive) layer bonded to a piezoelectric one. The direct ME effect is generated through the magnetic field-induced strain of the magnetostrictive particle/layer which is mechanically coupled to the piezoelectric part subjected to stress variations [12][13][14][15][16][17][18][19][20][21]; this latter transduces the stress to a voltage through its electromechanical conversion ability. Thus, the ME coupling is described as an extrinsic product property since neither phase (piezoelectric nor magnetic/magnetostrictive) is magnetoelectric.…”

“…Thus, the ME coupling is described as an extrinsic product property since neither phase (piezoelectric nor magnetic/magnetostrictive) is magnetoelectric. Intrinsic linear ME effect has been observed in single-phase materials (intrinsic ME effect) such as antiferromagnetic Cr2O3 crystal or multiferroic BiFeO3 compound but the associated ME susceptibilities are low compared to those of laminate composites [22][23][24][25][26][27].Among the piezoelectric compounds some specific functional polymers such as Poly(vinylidine Fluoride) (PVDF) polymer and its copolymer Poly(vinylidene fluride/trifluoroethylene) P(VDF-TrFE) have been widely studied and used as organic matrix in magnetoelectric structures for their interesting ferroelectric properties [7,9,10,11,[20][21][22][23][24][25][26][28][29][30][31][32][33][34]. Although the higher ME coefficients have been reported for ceramic composites [35], an advantage of using P(VDF-TrFE) -Fe3O4 composites is the more simple elaboration process in a various range of shapes and the absence of brittleness.…”

Effect of Bias Magnetic Field on Magnetoelectric Characteristics in Magnetostrictive/Piezoelectric Laminate Composites

“…Consequently, ME composite materials can be used as transducers in wireless powering systems, energy harvesting and magnetic field sensors, with the main advantage being that they require no external power to operate. Especially, the ME laminate composite has a relative higher ME voltage coefficient and a simpler fabricating procedure, which has attracted wide concern [2][3][4][5][6][7][8][9][10].…”

“…The traditional ME theories on the basis of the linear constitutive relationships of magnetostrictive material is inappropriate to describe the nonlinear ME response in a broad range of the bias magnetic field. Therefore, some theoretical researches about the influence of bias magnetic field on ME response are reported [5][6][7][8][9]. Liu et al tried to explain the problem by numerical and finite element methods, but it's still not enough to reveal the inherence of the dependence [6].…”