The dielectric properties and the phase transition behavior of $(1-x)Pb(Yb_{1/2}Nb_{1/2})O_3-xPb(Mg_{1/2}W_{1/2})O_3$ pseudobinary system have been investigated by X-ray diffraction, transmission electron microscopy, dielectric properties and E-P hysteresis loop measurements.
From the XRD and TEM measurements, the structure has been found to change from orthorhombic like pure PYN to orthorhombic like pure PMW via pseudocubic. As the composition of PMW increases, the transition temperature has been found to decrease gradually. From x=0.25, relaxor behavior has been found, even though the B-site ordering exists. For this relaxors, the hysteresis loops have changed from slim loop to linear type as the temperature is lowered. This may be interpreted that the local symmetry of nano polar region is antiferroelectric. In addition, the coexistence of antiferroelectric and relaxor phase has been observed in the crossover region of x=0.22.
