Phasic and microstructural developments of Pb(Ni1/3Nb2/3)O3 prepared by the columbite precursor process
Journal
Ceramics International
Journal Volume
22
Journal Issue
5
Pages
373-379
Date Issued
1996
Author(s)
Abstract
The phasic and microstructural developments of perovskite Pb(Ni1/3-Nb2/3)O3 during reaction processes using NiNb2O6 columbite precursor were investigated. Increasing the purity of NiNb2O6 in specimens efficiently enhanced the yield of the perovskite phase. Heating 1000°C-calcined NiNb2O6 with PbO at 880°C resulted in 97.5% perovskite phase. When NiNb2O6 was over-calcined, the grains of formed Pb(Ni1/3Nb2/3)O3 tended to grow significantly. The formation processes of Pb(Ni1/3Nb2/3)O3 were elucidated to be a reaction between PbO and NiNb2O6 to form a pyrochlore phase with a small amount of NiO at above 600°C. Then the pyrochlore phase partially decomposed to generate a trace of PbO from 700°C, and rapidly transformed to a perovskite phase at above 880°C. Pure Pb(Ni1/3Nb2/3)O3 was unable to synthesize when no excess of starting materials was added. However, adding excess 1 wt% NiO and 5 wt% PbO induced the generation of the monophasic Pb(Ni1/3Nb2/3)O3 perovskite. The excess amount of PbO not only increased the grain size markedly, but also enhanced the structural stability of the perovskite phase at elevated temperatures. © 1996 Elsevier Science Limited and Techna S.r.l.
Type
journal article