A New Method to Increase the Magnetoelectric Voltage Coefficients of Metglas/PVDF Laminate Composites
- PDF / 313,633 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 19 Downloads / 168 Views
1199-F06-08
A New Method to Increase the Magnetoelectric Voltage Coefficients of Metglas/PVDF Laminate Composites Zhao Fang1,2, Shengguo Lu2, Ninad Mokhariwale1,2, Mario El Tachchi3, and Qiming Zhang1,2 Department of Electrical Engineering and 2Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, U.S.A. 3 LPA-GBMI, Faculty of Sciences II, Department of Physics, Lebanese University, P.O. Box 90656, Jdeidet, Lebanon
1
ABSTRACT The magnetic flux density inside a Metglas sheet is much higher than that of the applied external magnetic field due to its high magnetic permeability, which is known as the magnetic flux concentration effect. Magnetic flux concentration of Metglas as a function of its sheet aspect ratio (width/length) was investigated for Metglas/Polyvinylidene fluoride (PVDF) laminar composites. Both the simulations and experimental results suggest that the magnetic flux concentration effect is markedly enhanced when the aspect ratio of a Metglas sheet is reduced. Consequently the magnetostriction of Metglas and the magnetoelectric (ME) voltage coefficients of the laminar composites are enhanced. The ME voltage coefficient for a laminar composite with a 1 mm wide and 30 mm long Metglas sheet (25 µm thick) is 21.46 V/cm·Oe, which is much higher than those reported earlier in similar laminar composites without making use of the flux concentration effect. The results demonstrate an effective means to significantly enhance the sensitivity of the magnetostrictive/piezoelectric composites as weak magnetic field sensors. INTRODUCTION The magnetoelectric (ME) effect [1-5] is the appearance of an electrical signal upon applying a magnetic field H and/or the appearance of a magnetic signal upon applying an electric field E. Although the ME effect was first observed in single phase materials [2] (e.g., Cr2O3), the laminate composites of magnetostrictive layer (e.g. Terfenol-D and Metglas) and piezoelectric layer [e.g., Pb(ZrTi)O3 (PZT) and polyvinylidene fluoride (PVDF)] have attracted much attention due to the strong coupling effect between the magnetostrictive and piezoelectric layers, which derive large ME coupling coefficients at room temperature and have potential to be used as high sensitivity magnetic sensors, electrical current sensors, and other devices [4-10]. Among the ME laminates which exhibit large ME coupling, the ones with Metglas are attractive due to their low saturation magnetization field. Consequently a relatively low dc bias magnetic field (< 20 Oe) is required to induce a large ME coupling in Metglas based ME composites, which is highly desirable for high sensitivity magnetic field sensors. Indeed, a sensitivity of 2×10-11 T/Hz1/2 at 1 Hz has been reported [11]. THEORY
For magnetic materials with very large permeability such as Metglas (µr>45,000), the magnetic flux concentration effect, a well known phenomenon, can be quite significant [12,13].
Illustrated in figure 1(a) is a two-dimensional demonstration of the flux concentration effect for a Metglas (
Data Loading...
