The phase transition behaviors of the $Pb_{1-x}Ba_x(Yb_{1/2} Nb_{1/2})O_3(PBYN)$ solid solution system (0 ≤ x ≤ 0.30) have been investigated by X-ray diffraction, permittivity and E-P hysteresis loop measurements. In the sold solution, a barium ion replaces a smaller lead ion on substitution.
For x ≤ 0.10, the transition shows a typical first-order paraelectric(PE) - antiferroelectric(AFE) behavior. Its low temperature phase AFE crystal structure is orthorhombic and is quite similar to that of PYN. The B-site ordering is maintained beyond 15mol% composition.
With increasing $Ba^{2+}$ substitution, the initially split fundamental lines of the XRDs merge into single lines and the transition temperature gradually decreases. Also, the emergence of FE phase coincides with the disappearance of $Pb^{2+}$ modulation.
The FE phase tends to consolidate on further $Ba^{2+}$ substitution in the composition range 0.12 ≤ x ≤ 0.14. In the SADP of 14mol% composition, uncommon (100) reflections are found. The (100) reflections are originated from the antiparallel A-site cation displacement which is in turn caused by oxygen octahedral inphase tilting. Therefore, It may be construed that ferroelectricity is influenced by the oxygen octahedral inphase tilting, and the $Pb^{2+}$ antiparallel displacement lines disappear beyond the 14mol% composition. With inphase tilting indicated by (100) reflections, it is now thought that a significantly large polarization is indicated in the solid solution.
On the composition range 0.16 ≤ x ≤ 0.30, a typical relaxor behavior is displayed and the crystal structure is pseudocubic at low temperatures below the transition temperature. In the SADP of 30mol% composition, the (100) reflections disappear again.
