PZT and lead-lanthane zirconate-titanate PLZT solid solutions

Lead zirconate-titanate (PZT) and lead-lanthane zirconate-titanate (PLZT) solid solutions 

Comparison of different commercially available Zr02 samples in sintering of PZT ceramics has demonstrated that crystallization of PZT occurs in one step only if samples prepared by hydrolysis of alkoxides are used [1697], 

Modification by acetylacetone is a powerful route, that allows precursor solutions to be stabilized. Interaction of titanium alkoxides with acetylacetone was extensively studied and reviewed in [1391,86]. Study ofreactions, occurring on interaction of Zr(OPrn)4 and Ti-Zr alkoxide mixture with acetylacetone, was performed in [1448] and allowed the authors to simplify the technique for preparation of precursor solution for PZT films application and to overcome the requirement of prolonged refluxing, which certainly decreases reproducibility. After dissolution of titanium and zirconium alkoxides in methoxyethanol, acetylacetone is added to form stable zirconium and titanium stock solutions. The introduction of acetylacetone allowed aqueous lead acetate (and lanthanum acetate for PLZT films) solutions to be added to mixed titanium and zirconium solutions. No reaction steps involving elevated temperatures or distillation or long reaction times are required. The solution could be used both immediately on mixing or after storage for several months. Such solutions were successfully used for application of ferroelectric films. 

Another approach to sol-gel PZT precursors involves the reaction of alkoxide mixture with glacial acetic acid [1442, 1790], Lead acetate and titanium 

Solutions prepared by any of the above-described techniques are spun onto the rotating substrate and dried at the temperature ranging from 150 to 450°C. Spin coating and drying are usually repeated several times. The coated films are finally annealed at 650°C for crystallization. Rapid thermal annealing (RTA) is frequently used for crystallization, demonstrating a positive impact on per-ovskite phase crystallization. It was also demonstrated by numerous workers that excess of lead (about 10% over stoichiometry) has to be introduced to compensate for the partial evaporation of volatile PbO during thermal treatment. This also allows the formation ofpyrochlore admixtures, which represents the major obstacle in the course of PZT films crystallization, to be overcome. 

---