Role of Fluorite Formation in Orientation Selection in Sol-Gel Derived Pb(Zr,Ti)O 3 Films on Pt Electrode Layers G. J. Norga 1‡ , L. Fè 1 , F. Vasiliu 2 , D. J. Wouters 1 , O. Van der Biest 3 1 IMEC vzw, Kapeldreef 75, B-3001 Leuven, Belgium 2 National Institute of Materials Physics, PO Box MG-7, R-76900, Bucharest-Magurele, Romania 3 KU Leuven, MTM Department, Kasteelpark 44, B-3001 Leuven, Belgium ABSTRACT We present evidence that the microstructure of the metastable fluorite phase Pb 2 (Zr,Ti) 2 O 6 , which forms during the pyrolysis treatment of sol-gel PZT layers by homogeneous nucleation throughout the film, has a larger impact on orientation selection than has previously been realized. Elaborate TEM studies demonstrate that by varying the pyrolysis time, temperature and duration, the crystallinity of the transient fluorite phase can be greatly influenced. Pyrolysis at 350°C leads to the formation of a well crystallized fluorite phase with a cubic structure (Fd3m space group) and a= 10.5-10.6 Å. Rapid crystallization of the transient fluorite phase is attributed to the low oxygen partial pressure conditions, prevailing during burnoff of acetate groups originating from the lead starting compound. A possible connection between the fluorite formation kinetics and orientation selection in the layers is discussed. INTRODUCTION While the sol-gel method has been shown to be suitable for the production of high-quality, oriented PZT films, the exact mechanisms governing orientation selection on different electrode layers remain still under debate. Many authors have attributed the observed dependence of film orientation on pyrolysis conditions to the formation of transient interfacial compounds, which could seed the nucleation of grains with fixed out-of-plane orientation during the crystallization treatment [1-3]. In earlier publications [4,5], we have presented evidence based on AR-FTIR (absorption-reflection-FTIR) measurements, showing that the chemical structure of the pyrolysed film can vary significantly depending on the details of the pyrolysis treatment. In turn, orientation selection during the crystallization step is drastically affected by the chemical structure (OH and residual organic content) of the pyrolysed film. The increase in the (111) texture component obtained by N 2 crystallization, which was especially pronounced for thinner films, identified however the oxygen partial pressure during crystallization as the single dominant factor controlling orientation selection [6]. To elucidate the detailed structural cause behind the chemical effects observed earlier, we report here on TEM investigations of films pyrolysed under different conditions (temperature, duration, number of pyrolysis steps). A fuller account of the results obtained will be given in a forthcoming paper [7]. ‡ Present address: IBM Research, Zurich Research Laboratory, Säumerstrasse 4, CH8803 Rüschlikon, Switzerland. Mat. Res. Soc. Symp. Proc. Vol. 688 © 2002 Materials Research Society C1.2.1