The effect of height on performance of the PZT/Ni cylindrical bilayered magnetoelectric (ME) composites was studied in situ in this paper. Multiple resonant peaks appear between 1 and 300 kHz frequency for cylinders of different heights. The first resonance frequency does not change with the cylinder height decreasing, but the second and the third resonant frequencies increase. The first three resonant modes are attributed to the cylinder radial, first-order height resonance, and second-order height resonance, respectively. The appropriate size and resonance frequency were chosen to obtain the highest ME voltage coefficient when designing cylindrical bilayered magnetoelectric devices. This article provides reference to design cylindrical magnetoelectric devices.

•The behavior of Pb in geopolymer depends on the chemical property of the Pb compound.•Pb participates in the formation of geopolymer network, forming leaded amorphous gel.•Dissolution of lead compounds is a vital step in the formation of leaded geopolymer.•Pb compounds, soluble in alkali, are chemically bonded into the geopolymer gel.•PbS, inert to alkali, is trapped in the geopolymer by physical encapsulation.Geopolymer possesses good immobilization capacity for Pb. There are two rival interpretations regarding the immobilization mechanism of Pb. This research investigates the behavior of 3 Pb compounds in geopolymer and clarifies the immobilization mechanism. When Pb contamination is added in the form, soluble in sodium hydroxide solution, the Pb is converted to an amorphous form and participates in the formation of geopolymer network. Successful immobilization of these species relies on chemical bonding and physical encapsulation. On the contrary, the Pb compound inert to sodium hydroxide solution is segregated from the binder and trapped by physical encapsulation.

•Magnetic warm compaction technology was utilized to prepare bi-layered ME composite.•The ME coefficient of newly prepared composite was enhanced.•Magnetic warm compaction technology is suitable for preparing Terfenol-D composite.•The magnetic field is key factor in the magnetic warm compaction technology.In this paper, bi-layered magnetoelectric (ME) composites laminated with the bonded Tb1−xDyxFe2−y (Terfenol-D) prepared by means of magnetic warm compaction and (Pb(Zr0.52Ti0.48)O3 (PZT-5H) ceramics were developed. The results show that the transverse ME voltage coefficient of ME composite is about 6 V/cm Oe, 3 times of that prepared by traditional room temperature pressure molding, implying that the magnetic warm compaction technology is an promising way to prepare the bonded Terfenol-D laminated ME composites. Additionally, the enhanced ME voltage coefficient is related to the preferred orientation of the Terfenol-D, and the magnetic field is key factor in the magnetic warm compaction technology.

•Ni–P(Ni)/PZT/Ni–P(Ni) cylindrical layered magnetoelectric (ME) composites were prepared.•αE,A dependence on HDC exhibits low Hdc,opt and a good linearity in the Ni–P/PZT/Ni–P composites.•Ni–P/PZT/Ni–P composite with 9.87% phosphorus content has the best comprehensive ME performance.Ni–P(Ni)/PZT/Ni–P(Ni) cylindrical layered magnetoelectric (ME) composites have been prepared with varying phosphorus content. The axial ME voltage coefficient, αE,A, was studied in this paper. The Ni–P/PZT/Ni–P composites show lower optimal magnetic field, Hdc,opt, along with better linearity of the ME voltage coefficient, compared with the Ni/PZT/Ni composite. These effects may be caused by the high permeability of Ni–P layers. This study helps selecting the appropriate phosphorus content to reduce the magnetic field on the premise of the high ME effect.