Yanmin Jia

Converse magnetoelectric effect in three-phase composites of piezoceramic, metal cap, and magnet

We report experimentally and theoretically the converse magnetoelectric (CME) effect in a three-phase piezoceramic-metal-cap-magnet composite made by sandwiching a thickness-polarized Pb(ZrxTi1−x)O3 (PZT) disk between two truncated conical brass caps and two thickness-magnetized SmCo disks. The reported CME effect originates from the product of the converse piezoelectric effect in the PZT disk, the mechanical transformation/amplification effect in the brass caps, and the magnetic induction effect in the SmCo disks. The composite exhibits a large CME coefficient (αB) in excess of 2mG∕V with a flat response in the broad frequency range of 0.1–100kHz. The measured magnetic flux density shows an extremely linear relationship to the applied voltage with amplitude varying from 10to100V over a wide range of detection distance of 0.7–6.5mm. This electromechanomagnetically coupled effect enables applications of the composite in coil-free magnetic flux control devices, featuring smaller Joule heating loss, wider operational bandwidth, and greater property-tailorable flexibility compared to conventional electromagnet-based devices.We report experimentally and theoretically the converse magnetoelectric (CME) effect in a three-phase piezoceramic-metal-cap-magnet composite made by sandwiching a thickness-polarized Pb(ZrxTi1−x)O3 (PZT) disk between two truncated conical brass caps and two thickness-magnetized SmCo disks. The reported CME effect originates from the product of the converse piezoelectric effect in the PZT disk, the mechanical transformation/amplification effect in the brass caps, and the magnetic induction effect in the SmCo disks. The composite exhibits a large CME coefficient (αB) in excess of 2mG∕V with a flat response in the broad frequency range of 0.1–100kHz. The measured magnetic flux density shows an extremely linear relationship to the applied voltage with amplitude varying from 10to100V over a wide range of detection distance of 0.7–6.5mm. This electromechanomagnetically coupled effect enables applications of the composite in coil-free magnetic flux control devices, featuring smaller Joule heating loss, wider op...

Converse magnetoelectric effect in laminated composites of PMN-PT single crystal and Terfenol-D alloy

We have found experimentally and theoretically that laminated composites comprising one layer of length-magnetized Tb0.3Dy0.7Fe1.92 (Terfenol-D) magnetostrictive alloy sandwiched between two layers of thickness-polarized, electro-parallel-connected 0.7Pb(Mg1∕3Nb2∕3)O3–0.3PbTiO3 (PMN–PT) piezoelectric single crystal have a large converse magnetoelectric effect characterized by a large magnetic induction in response to an applied ac voltage. The reported converse magnetoelectric effect originates from the product of the converse piezoelectric effect in the PMN–PT layers and the converse magnetostrictive effect in the Terfenol-D layer. Large converse magnetoelectric coefficient in excess of 105mG∕V is obtained in the composites at a low magnetic bias field of 170Oe. The measured magnetic induction has an excellent linear relationship to the applied ac voltage with amplitude varying from 50to160V. These made the composites to be a promising material for direct realization of core-free magnetic flux control de...

Remanent-polarization-induced enhancement of photoluminescence in Pr3+-doped lead-free ferroelectric (Bi0.5Na0.5)TiO3 ceramic

We found that ferroelectric remanent polarization can remarkably enhance the photoluminescence intensity of Pr3+-doped lead-free (Bi0.5Na0.5)TiO3 ceramics. An enhancement in photoluminescence intensity of ∼35% was obtained in the 0.5 mol. % Pr3+-doped sample, attributed to the decrease of crystal symmetry that occurs in poled ferroelectric ceramics. Our results reveal the great potential to enhance the photoluminescence intensity in rare-earth doped ferroelectric ceramics through ferroelectric polarization and to monitor the ferroelectric remanent polarization strength through measuring the photoluminescence spectra. We also found that the threshold of Pr3+ concentration quenching increased in the poled Pr3+-doped lead-free (Bi0.5Na0.5)TiO3 ceramic sample.

Dual-enhancement of ferro-/piezoelectric and photoluminescent performance in Pr3+ doped (K0.5Na0.5)NbO3 lead-free ceramics

A mutual enhancement action between the ferro-/piezoelectric polarization and the photoluminescent performance of rare earth Pr3+ doped (K0.5Na0.5)NbO3 (KNN) lead-free ceramics is reported. After Pr3+ doping, the KNN ceramics exhibit the maximum enhancement of ∼1.2 times in the ferroelectric remanent polarization strength and ∼1.25 times in the piezoelectric coefficient d33, respectively. Furthermore, after undergoing a ferro-/piezoelectric polarization treatment, the maximum enhancement of ∼1.3 times in photoluminescence (PL) was observed in the poled 0.3% Pr3+ doped sample. After the trivalent Pr3+ unequivalently substituting the univalent (K0.5Na0.5)+, A-sites ionic vacancies will occur to maintain charge neutrality, which may reduce the inner stress and ease the domain wall motions, yielding to the enhancement in ferro-/piezoelectric performance. The polarization-induced enhancement in PL is attributed to the decrease of crystal symmetry abound the Pr3+ ions after polarization. The dual-enhancement of...

Mn-doped 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 pyroelectric crystals for uncooled infrared focal plane arrays applications

3mol%Mn-doped 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single crystals were grown by a modified Bridgman technique. The pyroelectric properties and thermal stability of the crystals were investigated. Mn substitution resulted in an enhanced pyroelectric coefficient and a lower dielectric loss, which led to the improvement of the detectivity figure of merit of doped crystals by about a factor of 4 at 50Hz compared with that of pure crystals. Moreover, the thermal stability was enhanced by Mn substitution. The mechanism of doping effect is explained by the fact that the domain walls are pinned by the dopant dipolar defects, which optimizes the pyroelectric performance of 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 for uncooled infrared focal plane arrays applications.

High magnetoelectric effect in laminated composites of giant magnetostrictive alloy and lead-free piezoelectric ceramic

Magnetoelectric (ME) laminated composites with all phases environmentally friendly were prepared by sandwiching one layer of thickness-polarized (Bi1∕2Na1∕2)TiO3-(Bi1∕2K1∕2)TiO3-BaTiO3 lead-free piezoelectric ceramic disk between two layers of thickness-magnetized Tb0.3Dy0.7Fe1.92 giant magnetostrictive alloy disk along the thickness direction. The composites exhibited the maximum ME voltage coefficient of 40.7 mV/Oe with a flat response in the measured frequency range of 0.1−20 kHz under a dc magnetic bias of 5 kOe. The induced ME voltage showed an extremely linear relationship to the applied ac magnetic field with amplitude varying from 3×10−5 to 10 Oe over a broad range of dc magnetic bias of 0−5.5 kOe. The high ME effect was analyzed and found to be comparable to most major lead-based ME composites. The present study opens up possibilities for developing green ME devices.

Effects of Mn doping on dielectric and piezoelectric properties of 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single crystals

The dielectric and piezoelectric properties of the Mn-doped 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 (PMNT) crystals oriented along ⟨001⟩ and ⟨110⟩ directions, respectively, have been investigated. The investigations have shown that 3at.% Mn substitution results in (i) a large increment of coercive field at the cost of piezoelectric response, (ii) an increased Curie temperature and an enhanced stability of the ferroelectric rhombohedral phase, which enable a wider operation temperature range, and (iii) enhanced linearity in electric field induced strain with lower hysteresis. The hardened PMNT crystals favor their applications in high power transducers.

Piezoelectrically induced mechano-catalytic effect for degradation of dye wastewater through vibrating Pb(Zr0.52Ti0.48)O3 fibers

Hydrothermally synthesized piezoelectric Pb(Zr0.52Ti0.48)O3 fibers were used as a mechano-catalyzer to degrade acid orange 7 dye wastewater via the mechano-catalytic effect, which was achieved as a product of the piezoelectric effect and the electro-catalytic effect. When subjected to mechanical vibration, the Pb(Zr0.52Ti0.48)O3 fibers bend, which in turn induces electric charges on the surfaces of the fibers via the piezoelectric effect. The piezoelectrically induced electric charges induce chemical degradation reactions in the dye wastewater through the electro-catalytic effect. A high mechano-catalytic degradation ratio of ∼80% was achieved for the acid orange 7 solutions (∼30 μmol/l). The piezoelectrically induced mechano-catalytic effect thus provides a highly efficient and reusable technology for dye wastewater degradation applications.

Additional dc magnetic field response of magnetostrictive/piezoelectric magnetoelectric Laminates by Lorentz force effect

We have discovered that traditional long-type magnetoelectric laminate composite of magnetostrictive Tb1−xDyxFe2−y and piezoelectric materials possesses additional ability of detecting dc magnetic field, using the product effect of the Lorentz force effect from Terfenol-D metal strips in dc magnetic field applied with an ac electrical current and the piezoelectric effect from piezoelectric material. The output voltage between the two faces of piezoelectric (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystal shows a good linear response to applied dc magnetic field of 100–1200Oe under different ac electrical current inputs (0.4–200mA). The magnetoelectric coefficient is about ∼64.1mV∕TA. The additional dc magnetic field response of magnetostrictive/piezoelectric magnetoelectric laminates driven by Lorentz force makes this composite hopeful for application in coil-free ac/dc magnetic-sensitive sensors. At the same time, for this composite, the additional ability will not affect the primal ability for detecting ac ...

Electrical impedance dependence on the direct and converse magnetoelectric resonances in magnetostrictive/piezoelectric laminated composites

We fabricated two kinds of sandwiched magnetostrictive/piezoelectric composite and studied their magnetoelectric and electrical impedance properties. It was found that the electrical impedance resonance (fr) and anti-resonance (fanti−r) frequencies were, respectively, corresponded to the converse and direct magnetoelectric resonance ones. An equivalent circuit was developed to explain this phenomenon. The experimental result may be helpful in designing the magnetoelectric transducers.