Relaxor ceramics for multilayer capacitor application
Relaxor ferroelectrics, lead magnesium niobate (PMN) and lead zinc niobate (PZN) and their solid solution with lead titanate (PT) and barium titanate (BT) were studied. Unlike lead magnesium niobate, the pyrochlore-free material for lead zinc niobate could not be prepared by reaction between lead niobate and ZnO below 1000°C. However, some improved composition was obtained when lead zinc niobate (85%) and a mixture of lead titanate (10%) and barium titanate (5%) sintered at 950°C. XRD examination of the samples revealed that lead magnesium niobate prepared by us contained 9.9% pyrochlore phase, whereas the solid solution between 90% lead magnesium niobate and 10% lead titanate was completely free from the same phase. The dielectric constant for PZN-PT-BT (85:10:5) ternary system was 4000, whereas the same for lead magnesium niobate and its solid solution with 10% lead titanate was 4100 and 6000 respectively. The comparatively low value obtained for PZN-PT-BT solid solution was probably due to the presence of appreciable amount of pyrochlore phase. The grain diameter for PMN and PMN-PT (90:10) solid solution was 1.37/μM and 2.34μM respectively.
Volume 43, 2020
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