Relationship between dielectric properties and structural long-range   order in (x)Pb(In1/2Nb1/2)O3:(1-x)Pb(Mg1/3Nb2/3)O3 relaxor ceramics
  The dielectric and structural order-disorder properties of as-sintered complex perovskite (x)Pb(In1/2Nb1/2)O3:(1-x)Pb(Mg1/3Nb2/3)O3 ceramics are highly influenced by the quantity of Pb(In1/2Nb1/2)O3 (PIN). High PIN quantity causes the relative permittivity maxima to decrease and the temperature (Tmax) to increase. Also, strong frequency dispersion is dominant in the relative permittivity plotted against the temperature. In the ferroelectric hysteresis loop measurements, the maximum values of electric displacements (Dmax) decrease with increasing PIN. The ceramics in the composition range x = 0.1 to 0.8 behave as ferroelectric relaxors and exhibit very slim hysteresis loops for all these compositions. Transmission electron microscopy (TEM) studies show that the size of the 1:1 structural ordered domains is influenced by the PIN quantity. The relationship between the dielectric properties and the long-range 1:1 order in these relaxors appear to be in conflict with the commonly accepted order-disorder behavior in complex perovskite ferroelectrics, in which large structural domains correspond with the tendency to depart from the relaxor state. TEM observations show that individual 1:1 ordered domains in (x)PIN:(1-x)PMN ceramics are composed of numerous nano-sized ordered domains, separated by fine antiphase boundaries. 
C. W. Tai and K. Z. Baba-Kishi
cond-mat.mtrl-sci