Effects of additives (NiO, $MnO_2$) on the dielectric, piezoelectric and polarization-reversal properties of ($Pb_{0.936}La_{0.064}$) $(Zr_{0.60}Ti_{0.40})O_3$ ceramics have been investigated.
The specimens were prepared by the mixed oxide technique and atmosphere sintering method. The specimens were sintered at 1050℃ for 1 hour, 2 hours, and 3 hours in $O_2$ atmosphere. All the specimens thus obtained had tetragonal structures.
The dielectric constant and dissipation factor decreased with the addition of NiO or $MnO_2$. They had broadened maxima and their peak temperatures were not same.
The frequency dependence of Curie temperature was not observed. However, Curie temperature increased with the addition of NiO, but decreased with the addition of $MnO_2$.
The planar coupling factor was improved by addition of NiO and also increased with increasing sintering time. Addition of $MnO_2$ yielded a markedly high mechanical quality factor.
The space-charge field decreased with the addition of NiO, but increased with the addition of $MnO_2$.
The planar coupling factor and space-charge field showed same dependence on the additives.
The tetragonality, Curie temperature and planar coupling factor of ($Pb_{0.936}La_{0.064}$) $(Zr_{0.568}Ni_{0.032}Ti_{0.40})O_3$ were higher than those of ($Pb_{0.936}La_{0.064}$) $(Zr_{0.568}Ni_{0.032}Ti_{0.40})_{0.984}O_3$, but the grain size, lattice parameter, dielectric constant, dissipation factor, mechanical quality factor and space-charge field of the former were lower than those of the latter.
The planar coupling factor did not always decrease by the polarization-reversal field. This phenomenon cannot be explained by the space-charge model proposed by Okazaki et al.
