The phase transition behaviors of $(1-x)Pb(Yb_{1/2}Ta_{1/2})O_3-xPbZrO_3$ [(1-x)PYT-xPZ] solid solution system(0.0≤x≤0.40) have been investigated by dielectric permittivity, X-ray diffraction pattern, E-P hysteresis, and transmission electron microscopy(TEM) measurements. A highly ordered complex perovskite oxide, PYT shows two successive phase transitions, in which the first one is a normal-type paraelectric-antiferroelectric transition at 310℃ and the other is a frequency-dependent antiferroelectric-ferroelectric transition near 186℃. As the composition of PZ increases, the dielectric response of (1-x)PYT-xPZ system is classified into two groups. But macroscopic structural changes in XRD patterns are not observed so the structure of (1-x)PYT-xPZ system remains monoclinic at room temperature.
For x≤0.10, the phase transition behavior is similar to that of pure PYT. However, the temperature decrease of the secondary transition with frequency dispersion is more rapid than that of the PE-AFE primary transition. As $Zr^{4+}$ ion concentration increases, antiferroelectricity becomes predominant below the secondary transition and higher-order incommensurate superlattice reflections are obtained from selected area electron diffraction patterns(SAEDP). This may be interpreted as either strong coupling of antiferroelectric and ferroelectric domains as in PZST or randomly interacting dipole as in RADP system.
In the composition range of 0.15≤x≤0.40, only the primary transition emerges, where the dielectric constant maximum increases and its temperature, $T_m$ decreases. For x=0.25, the transition becomes broad and it coincides with the disappearance of superlattice lines of B-site cation ordering ($Yb^{3+}$, $Ta^{5+}$, and $Zr^{4+}$ ions) in XRD patterns. But their behaviors are different from those of relaxors.
