Preparation And Properties Of PZT-Ni Magnetoeletric Composites Film

Multiferroic magnetoelectric?ME?materials can not only display ferroelectric and ferromagnetic properties,but also couple the charge and spin order together to form new effects,such as ME effect.They exhibit enormous potential applications in transducers,sensors,memeries,and so on.Among them,ME composites have been attracting particular interests due to their ease in the miniaturization and low-power consumption.The present work in this dissertation focuses on the fabrications of film-on-metal ME structures at low temperatures and the characterization of direct ME effect of PbZr_0.52Ti_0.48O₃?PZT?/Ni and PZT/PbO/Ni composites with different thickness and orientations of PZT.By directly depositing PZT films on ferromagnetic Ni substrates,the film-on-metal ME structures were prepared at low temperatures with different thickness of PZT films.It effectively avoided the atomic inter-diffusion and reactions between two phases,as well as the micro-cracks due to thermal-expansion mismatch at high temperatures.PZT/Ni ME composites exhibites good magnetoelectric coupling.With a thickness of 250 nm,the PZT/Ni composites reaches a maximum?_E value of 102.9mV/cm·Oe at room temperature,which appears at a low H_dc.In addition,magnetoelectric coupling coefficients of PZT/Ni composites tracked the same bias-dependent trend as the piezomagnetic coupling coefficient of Ni substrates.It thus demonstrted that the coupling between PZT and Ni were dominated by the strain-mediated“magnetic-mechanical-electric”coupling.The PZT/PbO/Ni composites with[100]oriented PZT thin films were obtained by introducing the PbO seed layer.Different PZT film thicknesses can be achieved by modulating the cycles of the PZT/PbO spin-coating.The introduction of PbO seed layer changes the PZT film greatly.When the thickness of PZT is 325 nm,the maximum?_E value of PZT/PbO/Ni composites reaches as high as 421.4mV/cm·Oe,which is 4.1 times lager than that of PZT/Ni composites.