Relation between Fractal Inhomogeneity and In/Nb-Arrangement in Pb(In 1/2 Nb 1/2 )O 3 .

Relaxor ferroelectrics show substantial responses to electric fields. The key difference from normal ferroelectrics is a temperature-dependent inhomogeneous structure and its dynamics. The lead-based complex perovskite Pb(In1/2 Nb1/2 )O3 is an intriguing system in which the inhomogeneous structure can be controlled by thermal treatment. Herein, we report investigations of the phase transitions in single crystals of Pb(In1/2 Nb1/2 )O3 via changing the degree of randomness in which In and Nb occupy the B site of the ABO3 perovskite structure. We studied the dynamic properties of the structure using inelastic light scattering and the static properties using diffuse X-ray scattering. These properties depend on the degree of randomness with which the B site is occupied. When the distribution of occupied In/Nb sites is regular, the antiferroelectric phase is stabilised by a change in the collective transverse-acoustic wave, which suppresses long-range ferroelectric order and the growth of the inhomogeneous structure. However, when the B site is occupied randomly, a fractal structure grows as the temperature decreases below T* ~475 K, and nanosized ferroelectric domains are produced by the percolation of self-similar and static polar nanoregions.