High magnetoelectric effect at low magnetic basing in heterostructure rod of magnetostrictive fibers, piezoelectric tube, and epoxy binder

A three-phase heterostructure rod of 35 mm length and 8 mm diameter is developed by embedding 18 pieces of length-magnetized Tb_0.3Dy_0.7Fe_1.92 magnetostrictive continuous fibers in a wall-thickness-polarized Pb(Zr, Ti)O₃ piezoelectric long-thin tube using an epoxy binder in order to study its magnetoelectric (ME) effect for passive sensing of axial magnetic fields. The heterostructure rod exhibits a high non-resonance ME voltage coefficient (α_V) of 38 mV/Oe for frequencies up to 10 kHz and an ultrahigh resonance α_V of 680 mV/Oe at 32 kHz, both under a reasonably low magnetic bias field (H_Bias) of 120 Oe. The simultaneously high axial ME responses at the reasonably low H_Bias, as confirmed theoretically and experimentally, can be ascribed to the realization of the relatively true magnetostrictive 33-mode and piezoelectric 31-mode of operation in the magnetostrictive continuous fibers and piezoelectric long-thin tube, respectively, as well as the reduction in the effect of demagnetization fields in the high aspect-ratio magnetostrictive continuous fibers.