EFFECT OF THE ANNEALING TEMPERATURE ON STRUCTURAL AND PIEZOELECTRIC PROPERTIES OF THE SOL-GEL PB(ZR0.56TI0.44)(0.90)(MG1 3NB2/3)(0.10)O-3 FILMS/

Sol-gel Pb(Zr0.56Ti0.44)(0.90)(Mg1/3Nb2/3)(0.10)O-3 (PZT-PMN) films 1 mu m thick were prepared onto the Ti/Pt/Ti bottom electrodes by six la yer spin-coatings. After the first triple layer coatings, a pre-anneal ing was carried out by rapid thermal process (RTP) with a step pattern of 600 degrees C/5 min to 725 degrees C/1 min. Finally, after the lat er triple layer coatings, the films were heat-treated by RTP with a st ep pattern of 650 degrees C/5 min to 900 degrees C/1 min (low-temperat ure annealing) or 650 degrees C/5 min to 1050 degrees C/1 min thigh-te mperature annealing). The structural and piezoelectric properties of t he films were investigated by scanning electron microscopy (SEM), cros s-sectional transmission electron microscopy (XTEM), and by measuring the piezoelectric charge constant d(31), the piezoelectric voltage con stant g(31) as well as the relative permittivity epsilon. The films re tain the tetragonal perovskite structure independent of the final anne aling temperature. The interlayer caused at the middle depth of the fi lm by the pre-annealing prevents the columnar grain growth through the film. Many fine grains are grown in the interlayer to be rich in Zr a nd deficient in Pb. The fine grains rich in Zr and deficient in Pb are also formed on the surface of the film. The growth of such the Zr-ric h and Pb-deficient phase is effectively suppressed at the low temperat ure annealing rather than at the high temperature annealing. Thus, the piezoelectric films 1 mu m thick with high d(31), g(31) and epsilon a re successfully obtained with the low- temperature annealing. (C) 1998 Elsevier Science S.A.