Percolation processes and anomalous light scattering in ferroelectrics having a broad phase transition

The temperature dependences of small-angle light scattering were determined for lead scandotantalate and scandoniobate crystals characterized by low and high degrees of ion order (s). Scattering peaks were observed and the number of these peaks depended on s. A broad phase transition in these disordered crystals was accompanied by percolation-type processes. An analysis was made of the theoretical aspects of the interpretation of low-angle multiple scattering