Piezoelectric PZT ceramics have been investigated since 1950's for its high electromechanical properties.
Both PZT and $LaMnO_3$ were known to have perovskite structures. In this study, PZT+$LaMnO_3$ system was selected.
The dielectric and piezoelectric properties of $0.98-x Pb(Zr_{0.54}Ti_{0.46})O_3+0.02 LaMnO_3+x SrO(where \times 0.005, 0.01, 0.02 respectively)$ and $0.98(Pb_{1-x}Sr_x) (Zr_{0.54},Ti_{0.46})O_3+0.02 LaMnO_3$ (where \times 0, 0.03, 0.06, 0.10, 0.15) have been investigated.
The specimen were prepared by calcination and conventional sintering method. The specimen were sintered at 1200, 1225, 1250, 1275 and 1300℃for an hour respectively. All the specimen had been found to have tegragonal structures. In (Pb,Sr)(Zr,Ti)$O_3$-0.02$LaMnO_3$ system, when the content of Sr is 6% axial ratio $(c_o/a_o)$ is maximum.
$0.98(Ph_{1-x},Sr_x)(Zr_{0.54},Ti_{0.46})O_3+0.02 LaMnO_3$ systems seem to undergo liquid phase sintering and we observed domains in the grain by optical microscope and scanning electron microscope.
In the substitution of Sr for Pb in $0.98Pb(Zr_{0.54},Ti_{0.46})O_3-0.02 LaMnO_3$, when 3 mole per cent Sr was doped, dielectric constant after poling was lower than that of unpoled specimen. But in substitution of 6-10 mole per cent Sr, dielectric constant after poling was not lower than that before poling.
In the substitution of Sr, planar coupling factor (kp) seemed to increase with c/a (axial) ratio.