Analysis of the conditions favoring the onset of long-range order in disordered relaxors of different types

The possibility of realizing a stable relaxor behavior in PbSc1/2Nb1/2O3 (PSN) compounds and the conditions favoring the formation of a phase with long-range order in PbZn1/3Nb2/3O3 (PZN) are studied using optical methods. It is found that the replacement of only 6% of Pb ions with Ba ions (PBSN-6) freezes the relaxor state in PSN compounds, while adding even 7% of PbTiO3 to the PZN relaxor (PZN-7PT) leads to the formation of a phase with long-range order and a phase transition occurring at T.,,x, through the percolation mechanism. Common features in the formation and destruction of the Ion-range order phase in relaxors of difC ferent types are revealed. The differences associated with the presence of spontaneously polarized ferroelectric regions in the cubic nonpolar matrix of PSN-type compounds are determined.