Effect Of The Piezoelectric Phase On The Magnetoelectric Performance Of Magnetoelectric Laminated Composites

The layered ME composites prepared by electroless deposition possess a large ME effect, and thecylindrical laminated composites have attracted much attention because of their superior MEproperties at room temperature, particularly. To further enhance the ME properties and investigate thefactors which affect the ME effect both structures and piezoelectric materials were optimized. Theeffect of piezoelectric phase on the ME performance of ME laminated composites have beeninvestigated.This thesis first proves that with the radial polarized piezoelectric cylinders the ME compositespossess better ME coupling. On this foundation, effects of height and wall-thickness of thepiezoelectric cylinder on the ME performance for FeCo/PZT/FeCo cylindrical laminated compositeshave been taken into consideration. It was shown that when the wall-thickness is the same, as thecylinder height increases the ME coefficient increases while the resonance frequency graduallydecreases for FeCo/PZT/FeCo cylindrical laminated composites. When the cylinder height is the same,as the wall-thickness increases the ME coefficient of FeCo/PZT/FeCo laminated composites decreaseswhile the resonance frequency gradually increases.The ME performances of FeCo/PMN-PT/FeCo laminated composites have also beeninvestigated. It suggests that the piezoelectric crystal orientation have no effect on the FeCo alloyfilms prepared by electroless deposition. For the square FeCo/PMN-PT/FeCo sample, six obviousresonance peaks can be observed for the ME coefficient αEdue to the complex vibration mode. Thefirst and the second resonant peaks around170kHz are mainly attributed to the bending resonancemode, and the third to the sixth resonance peaks around300kHz are dominated by the planar acousticresonance mode. In addition, the ME composites comprised with three different crystal cuts ofPMN-PT piezoelectric substrates have been prepared. It reveals that theFeCo/<001>L×<0(1|-)1>W×<011>TPMN-PT/FeCo composites possess the largest ME coefficient, whilethe FeCo/<0(1|-)1>L×<100>W×<011>TPMN-PT/FeCo composites possess the largest resonantfrequency.