Many researchers have studied the powder preparation of PZT by coprecipitation. But little attention has been given to the effect of dewatering method of the coprecipitated hydroxides on sintered properties. In present work, the aqueous solution of starting materials such as lead nitrate, zirconium oxychloride and titanium chloride was mixed and consequently precipitated in the form of a complex-hydroxide gel by the addition of $NH_4OH$. under 50℃, pH9 condition. After water washing, the precipitated gel was washed by two dewartering method-open oven drying, ATA (acetone-toluene-acetone) washing-which made PZT powders different characteristics.
The PZT powders from coprecipitated complex hydroxide began to be synthesized at low calcination temperature (400℃, 3h), The powder produced by oven drying, had strong agglomerates, which must be crushed by grinding or ball milling, and of which primary particles were not identified. In the powders produced by ATA washing, the agglomerates appeared to be friable and the primary particles in the agglomerates were identified and showed as round shape. TEM micrographs of the state of powders in various solvents showed that the precipitated gel slightly flocculated in the water, but both in acetone and in toluene, the particles of gels were heavily agglomerated. The conclusion from this result was that drying conditions had more influence on agglomerates than dispersion state in solvents. Because agglomerates of ATA washed powders are weak and easily deagglomerated, they had fine particles and narrow particle size distribution, and ATA washed specimen had nearly reached to theoretical density at 1150℃, while oven dried specimen had shown 95.5% theoretical density. The dielectric and piezoelectric properties of ATA washed specimen were superior to oven dried specimens.
