The sintering phenomena and piezoelectric properties of $(1-X)Pb(Zr,Ti)O_{3-x} LaMnO_3$ (where, x=0.02, 0.05, 0.1), 0.98 $Pb(Zr,Ti)O_3-0.02 LaCrO_3$, and 0.98 $Pb_{0.95}Sr_{0.05}(Zr_{0.54}Ti_{0.46})O_3+0.02 LaMnO_3$ have been investigated.
The specimens were prepared by the conventional ceramics preparation method. The specimens were sintered respectively at 1200℃, 1225℃, 1250℃, 1275℃, and 1300℃ for 1hour in $O_2$ atmosphere. $Pb(Zr,Ti)O_3-LaMnO_3$ solid solution thus obtained had tetragonal structure with c/a=1.035 and the theoretical density of 8.0 g/㎤ in $0.98Pb(Zr_{0.54}Ti_{0.46})O+0.02 LaMnO_3$.
When the content of $LaMnO_3$ increased, the density also increased with increasing sintering temperature, but the Curie temperature decreased. The $Pb(Zr,Ti)O_3-LaMnO_3$ system seemed to undergo liquid phase sintering, and the liquid phase could be observed by optical microscope and presumably the compound of $Pb(Zr,Ti)O_3$ and $LaMnO_3$.
The substitution of 5 mole % Sr for Pb in 0.98 $Pb(Zr_{0.54}Ti_{0.46})O_3+0.02 LaMnO_3$ effected to lower the Curie temperature and the grain size, but caused to increase the dielectric constant and made considerable improvement in planar coupling factor $k_p$.
The sintered density, dielectric constant, and planar coupling factor $k_p$ in $0.95Pb(Zr_{0.54}Ti_{0.46})O_3+0.05 LaMnO_3$, were almost independent of sintering temperature, and this system is considered to be out of the morphotropic phase boundary.
The mechanical quality factor $Q_M$ of the materials studied had the broad value range about 50-200.