Structural, compositional and piezoelectric properties of the sol-gel Pb(Zr0.56Ti0.44)(0.80)(Mg1/3Nb2/3)(0.20)O-3/Pb(Zr0.56Ti0.44)O-3 composite films

A 750 nm-thick PZT-PMN/PZT composite film was prepared by sequential multip le spin-coatings. First, a 375 nm-thick sol-gel Pb(Zr0.56Ti0.44)O-3 (PZT) l ayer was prepared on a Ti/Pt/Ti bottom electrode and then a 375 nm-thick Pb (Zr0.56Ti0.44)(0.80)(Mg1/3Nb2/3)(0.20)O-3 (PZT-PMN) layer was prepared on t he PZT layer. The structural, compositional and piezoelectric properties of the composite film were investigated by using X-ray diffraction, scanning electron microscopy, cross-sectional transmission electron microscopy and s econdary ion mass spectrometry and by measuring the piezoelectric charge co nstant d31, the piezoelectric voltage constant g31 and the relative permitt ivity epsilon. The composite film retains the tetragonal perovskite structu re with columnar grains. The lattice of the PZT-PMN layer smoothly connects to that of the PZT layer without forming any interfacial structure. Howeve r, the atomic composition, mainly in Mg and Nb, differs between PZT-PMN and PZT layers. The composite film has a higher piezoelectric charge constant d31 as compared with the PZT-PMN and PZT single films. The value of d31 is independent of the sequence of the PZT-PMN and PZT layers. (C) 1999 Elsevie r Science S.A. All rights reserved.