The Rietveld analysis of powder X-ray and neutron diffraction for SBT and Pb
xSr
1-xBi
2Ta
2O
9 revealed that Pb ions were substituted at the perovskite
A-site, and the disordering of Pb and Bi ions in Bi
2O
2 layers was not confirmed. The pure solid solutions with the SBT structure were obtained for the samples with
x≤0.6, and the unit cell volume slightly increased by Pb substitution. With increasing Pb content (
x), parameter
c grew while
a-b plane was reduced in spite of larger ionic radius of Pb
2+ than Sr
2+. These structure changes resulted in a higher
Tc for Pb-SBT. Polarization hysteresis measurements using dense ceramics revealed that
Ec increased with
x while 2
Pr at 250kV/cm practically remained constant at around 14μC/cm
2. The incorporation of Pb into SBT resulted in a higher tilt angle of TaO
6 octahedra along the
a-axis (α
x), which is partly responsible for the higher
Ec observed for Pb-SBT.
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