Abstract
The change in the shape and size of a material under a magnetic field is called "magnetostriction". The magnetostrictive materials can convert magnetic energy to mechanical energy. When a stress is applied onto a piezoelectric material, the material will produce a voltage proportional to the stress. This research studied a hybrid device consists of magnetostrictve and piezoelectric materials. It can convert from magnetic energy to mechanical energy then to electrical energy. The device was expected to output a distinguished voltage signal as an AC magnetic field is applied. TbFe2, which has giant saturated magnetostriction as magnetostrictive film, is deposited on a PZT ceramic substrate about 50μm thickness by magnetron sputtering. By tuning sputtering conditions the dynamic strain constant in low field can be improved to obtain high sensitity to AC field, and the film was found to be suitable for the device. In this study, the films sputtered for over 20 minutes showed perpendicular anisotropy and higher coercive force. This is not good for measuring magnetoelectric signals in plane. The films sputtered for 10 minutes had better magnetostriction. Better magnetoelectric conversion was resulted in the latter case although the thickness of the magnetostrictive film compared to piezoelectric substrate is only 1:150. The device has the best magnetoelectric conversion factor when biased at a magnetic field higher than 6kOe. The magnetoelectric signals suffered from aging and decaying after poling. The device with a film sputtered for 10 minutes and aging for 25 days after poling led to the best data, 10.31mV, under a bias field about 6kOe. The magnetoelectric conversion factor, ?E/?H, is 65.9mV/cm·Oe (82.8mV/A). The signal waveforms of the magnetoelectric devices were also elucidated. The devices were found to be applicable in practice.