In¯uence of PZT template layer on pulsed laser deposited Pb(Mg1/3Nb2/3)O3 thin ®lms

Lead magnesium niobate (PMN) thin ®lms were prepared by pulsed laser deposition technique on different substrates. Because of the ®t of the unit cell structure and lattice constant with PMN, lead titanium zirconate (PZT) template layers have been deposited on top of the bottom electrodes, while another set of samples has been prepared by directly depositing PMN on metallized substrates. The use of PZT layer favored the obtaining of an oriented crystalline PMN ®lm with a minor pyrochlore content at relatively low temperature (5008C). The room temperature small-signal dielectric constant of the ®lms has been measured on structures with 1mm 1mm evaporated Au top electrodes, by using an impedance analyzer. The obtained values of the dielectric constant have been found to be much smaller than that of bulk PMN, due to the presence of a very thin transition layer with low dielectric constant at the electrode/®lm interface, which highly decreases the effective dielectric constant of the samples. The measurement of the piezoelectric properties evidenced the rather surprising presence of a relatively strong piezoelectric effect in PMN ®lms in the absence of a bias electric ®eld. # 2000 Elsevier Science B.V. All rights reserved.