THESIS
2016
xix, 219 pages : illustrations ; 30 cm
Abstract
Piezoelectric and magnetostrictive materials have attracted a great attention from researchers due to their excellent sensing properties and successful applications in intelligent structure in past decades. In this study, a new magnetoelectric (ME) composite by incorporating these two phases together into cement matrix is successfully developed with satisfactory properties for the first time in the world. This new composite exhibits a brand new ME behavior: the strain of the magnetostrictive phase caused by the magnetic field induces a stress on the piezoelectric phase, then an electric field is generated for the measurement.
Considering its prior key ME characteristics, cement-based 2-2 laminate ME composite composed of lead zirconate titanate (PZT) layer sandwiched between two ceme...[
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Piezoelectric and magnetostrictive materials have attracted a great attention from researchers due to their excellent sensing properties and successful applications in intelligent structure in past decades. In this study, a new magnetoelectric (ME) composite by incorporating these two phases together into cement matrix is successfully developed with satisfactory properties for the first time in the world. This new composite exhibits a brand new ME behavior: the strain of the magnetostrictive phase caused by the magnetic field induces a stress on the piezoelectric phase, then an electric field is generated for the measurement.
Considering its prior key ME characteristics, cement-based 2-2 laminate ME composite composed of lead zirconate titanate (PZT) layer sandwiched between two cement-based Tb
1-xDy
xFe
2 alloy (Terfenol-D) layers is chosen for systematical investigation on the overall performance. This composite shows excellent dielectric and piezoelectric properties with equivalent permittivity to pure PZT. The ME property of composites is strongly dependent on the applied magnetic field H
dc and H
ac, frequency, connectivity, composition proportion and the magnetic field orientation. At 1 kHz, the ME composite with the intermediate PZT volume fraction of 0.44 exhibits the maximum ME response
αE31 of 1315 mV/cm·Oe. This giant ME response can be considered as the best ME performance ever found, and is much superior to that of other polymer-based composites (just about 200-300 mV/cm·Oe) reported. Such great ME coupling sensitivity can be attributed to the giant magnetostriction induced in Terfenol-D layer, and strong mechanical coupling interaction among different phases because that cement matrix functioned not only as particles binder, but also as the transmission medium with higher transfer efficiency. Such superior properties and excellent performance made this novel ME composite be a strong potential candidate for engineering applications as sensors, actuators and other smart transducers.
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