Perovskite phase formation and microstructural evolution of lead magnesium tungstate-lead titanate ceramics
Journal
Journal of Materials Science
Journal Volume
31
Journal Issue
3
Pages
699-705
Date Issued
1996
Author(s)
Abstract
The perovskite phase formation and microstructural evolution in the Pb(Mg 0.5 W 0.5 )O 3 -PbTiO 3 system have been investigated in this work. During the solid-state reaction of Pb(Mg 0.5 W 0.5 )O 3 , only PbWO 4 and Pb 2 WO 5 are formed as intermediate phases at low temperature range. Moreover, the perovskite phase Pb (Mg 0.5 W 0.5 )O 3 begins to form at 600¢XC and is complete at 850¢XC. As Pb(Mg 0.5 W 0.5 )O 3 is doped with PbTiO 3 , the formation of the perovskite phase becomes sluggish and the temperature for the complete reaction to take place increases up to 1000¢XC. The doping of the Pb(Mg 0.5 W 0.5 )O 3 with PbTiO 3 apparently induces the formation of a small amount of liquid phase, which is possibly attributed to a reaction with residual Pb 2 WO 5 . This liquid phase not only accelerates the densification of specimens through a liquid phase sintering mechanism, but also causes abnormal grain growth, thereby forming an inhomogeneous microstructure. The dielectric permittivity of Pb(Mg 0.5 W 0.5 )O 3 does not depend on frequency, and a sharp phase transformation from the antiferroelectric to the paraelectric state occurs at around 40¢XC. In contrast, the dielectric properties and broad phase transformation temperatures of Pb(Mg 0.5 W 0.5 ) 0.9 Ti 0.1 O 3 and Pb(Mg 0.5 W 0.5 ) 0.6 Ti 0.4 O 3 strongly depend on frequency. This dependency would imply that the PbTiO 3 addition to Pb(Mg 0.5 W 0.5 )O 3 alters the order arrangement of B-site cations to a disordered state and induces relaxor-ferroelectric characteristics. ? 1996 Chapman & Hall.
Type
journal article