Electrical and Electromechanical Properties of Bi4-xLnxTi3O12 Ceramics

Ferroelectric Bi
4
Ti
3
O
12
and $\mathrm{Bi}_{4-\mathrm{-}} \mathrm{Ln}_{\mathrm{x}} \mathrm{Ti}_3 \mathrm{O}_{12}(\mathrm{x}=$ $0.75, \mathrm{Ln}=\mathrm{La}$ or Nd) ceramics were fabricated by solid state reaction. Additive compounds of La and Nd deteriorated sinterabilities of the ceramics. Ceramic samples were prepared by normal sintering, but were oriented with the c-axis perpendicular to the disk. The La and Nd additions reduced the leakage component and resulted in a well-saturated polarization hysteresis loop. Compared to the disk samples, the cross-sectional samples exhibited larger polarizations and electric field-induced strains. From the slope of the strain loops, the effective $d_{33}$ are estimated to be $12.5 \mathrm{pm} / \mathrm{V}, 10.6$ $\mathrm{pm} / \mathrm{V}$ and $6.3 \mathrm{pm} / \mathrm{V}$ for $\mathrm{Bi}_4 \mathrm{Ti}_3 \mathrm{O}_{12}, \mathrm{Bi}_3 .25 \mathrm{La}_{0.75} \mathrm{Ti}_3 \mathrm{O}_{12}$, and Bi
3.25
Nd
0.75
Ti
3
O
12
, respectively.