Lead Zirconate-Lead Titanate (PZT) Ceramics from Organic-Derived Precursors
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Lead Zirconate-Lead Titanate (PZT) Precursors
Ceramics From Organic-Derived
R. G. Dosch, Sandia National Laboratories, New Mexico 87185
P.
0. Box 5800,
Albuquerque,
ABSTRACT Organic-derived precursors can facilitate the preparation of PZT ceramics, particularly in the areas of processing and batch reproducibility. The use of partially alkoxide-derived precursors and completely organic-derived precursors has been studied. Two methods of alkoxide hydrolysis were evaluated for preparing zirconia which included direct hydrolysis in water and hydrolysis of alkoxide-base reaction products in acetone-H2 0 mixtures. The chemistry of these methods is discussed along with pertinent aqueous surface chemistry of the hydrated zirconia products. This work suggests that alkoxide-derived precursor properties are related to the solution chemistry used in their preparation.
INTRODUCTION The use of chemical preparation techniques for making ceramic precursors is generaly stimulated by specific requirements which cannot be readily met by conventional ceramic processing methods. Examples encountered in our laboratory have included needs for improved batch reproducibility, homogeneous distribution of trace constituents, reduction of processing complexity, and for amorphous ceramic compositions. The
former is of particular interest for lead zirconate-lead titanate (PZT) materials as batch variation in physical and electrical properties has been a recurring problem over the years.
A number of options are apparent in applying organic-derived precursors to PZT fabrication. The composition Pb. 9 9 Nb.o2 (Zr. 9 6 Ti. 0 4 ).9803 (PNZT) is of particular interest and precursor routes investigated have included the use of metal alkoxide-derived Zr0 2 and ZrO2 - TiO2 - Nb2 05
mixtures in combination with the appropriate commercially available oxides and also a completely organic-derived precursor prepared via a non-aqueous reaction of alkoxide mixtures with lead lactate. The properties and processing characteristics of PNZT materials prepared using these precursor options have been reported elsewhere(l). Work in our laboratory has shown that one of the most important variables relative to PZNT properties is the characteristics of the Zr02 raw maerial. 2 Similar observations have been reported for other PZT compositions( ). In this paper an attempt is made to relate differences in properties of the Zr02 powders and the PZNT prepared from them to the solution chemistry used in the ZrO2 preparation.
*This work performed at Sandia National Laboratories supported by the U.S. Department of Energy under contract number DE-AC04-76DP00789.
Mat.
Res.
SOc.
Syrp.
Proc. Vol.
32 (1984)
Published by Elsevier Science Publishing Co., Inc.
200
Experimental Two hydrous Zr0 2 precursors were prepared from tetra-n-propyl zirconate, TPZ, (28.79% ZrO2 equivalent) as follows: For Zr0 2 -I, TPZ 3 ( 55g) was added to 2 liters of boiling water. After stirring 15 minutes, the solids were separated by filtration, washed with acetone, and dried 0 34 at 22
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