No abstract

No abstract

The effect of lead zirconate titanate (PZT) powder loading in the slurry on wall thickness of PZT microtubes formed by dip coating on vermicelli of diameters about 500 and 1000 mm has been reported. The vermicelli of 1000 mm diameter withstand longer dipping time (8 min) compared to vermicelli of diameter 500 mm (2 min). The wall thickness of the PZT microtubes formed by dip coating increased with both slurry loading and dipping time. The PZT microtubes by dip coating on vermicelli of 1000 mm diameter have thicker walls than that obtained with vermicelli of diameter y500 mm due to higher water absorption capacity of the former. Microtubes of PZT with wall thickness in the ranges of about 125 to 280 mm and about 220 to 480 mm could be prepared by dip coating of slurries of PZT powder loading in the range of 40?2 to 46?5 vol.-% on vermicelli of diameters 500 and 1000 mm respectively.

PZT microtubes have been fabricated by dip coating of aqueous PZT powder slurry on vermicelli, followed by burnout of the vermicelli and sintering. The water-absorbing character of the vermicelli made a thin layer of PZT slurry to gel on its surface during dip coating. Thickness of the gel on the surface of the vermicelli depends on the dipping time. The green PZT layer thickness in the range of 140-190 lm could be achieved for a dipping time of 30-120 s. Microtubes having an inner diameter of nearly 500 lm with wall thickness in the range of 120-160 lm could be prepared by this process.M. Kuwabara-contributing editor

No abstract

No abstract

Powder compaction and sintering characteristics of the PMN-PT powder prepared by the partial oxalate route have been studied. The PMN-PT powder achieved 60% of theoretical density during compaction by pressing at 100 MPa. The powder compacts were sintered to > 99% TD at 1270 • C for 2 hours. Microstructure of the sintered ceramic showed an average grain size of 6.1 µm. Absence of any pyrochlore phase in the sintered PMN-PT ceramics has been established through XRD analysis. The piezoelectric characteristics of the sintered PMN-PT ceramics have been evaluated. The polarization and strain behaviour of the PMN-PT ceramics has been evaluated and the results are discussed. The PMN-PT ceramics prepared by the partial oxalate route showed d 33 (750 pC/N) and k p ( 0.62.) values higher than that reported for the same prepared by solid state route.

Preparation of monodisperse nanocrystalline yttria doped ceria powder by the oleate complex route has been reported. Y(III) and Ce(III) oleate complexes have been prepared by the reaction between YCl 3 , Ce(NO 3 ) 3 and sodium oleate at the interface of hexane rich and water rich conjugate layers of water-ethanol-hexane ternary liquid system. Cubic yttria doped ceria crystallises when the waxy solid containing Y(III) oleate and Ce(III) oleate complexes was heat treated at 400uC. The powder after planetary ball milling contains monodisperse near spherical particles of 0?2 mm. These particles contain monodisperse nanocrystallites of size ,10 nm. The yttria doped ceria powder pellets were sintered to .98% theoretical density at 1450uC. The sintered ceramic showed an ionic conductivity of 0?0623 S cm 21 at 800uC and activation energy of 1?0 eV.