
163Experiments
5.2.7 Three-Phase High-μ
Composites [41, 42]
In prior chapters, we have seen that two-phase magnetostrictive/
piezoelectric laminates or composites exhibit large ME coupling
only near an optimum dc magnetic bias H
dc,opti
dλ/dH) of the magnetostrictive layers
is maximum [22, 38]. Typical values of H
dc,opti
for L–T and L–L ME
laminates are about 500 Oe, whereas those operated in T–T modes
may have H
dc,opti
as high as 4000 Oe [17, 24]. These relatively high H
dc,opti
are due to the low magnetic permeability μ
r
of the magnetostrictive
materials that