Broadband micro-brillouin scattering study of 0.7Pb(Sc1/2Nb1/2)O3-0.3PbTiO3 crystals

The critical behavior of a relaxor ferroelectric 0.7Pb(Sc
_1/2
Nb
_1/2
)O
₃
-0.3PbTiO
₃
(PSN-0.3PT) crystal is studied by the broadband micro-Brillouin scattering. Remarkable and continuous elastic anomaly is observed in the vicinity of the Curie temperature T
_C
=500 K. The integrate intensity of a central peak obeys the Curie-Weiss law. The relaxation length of strain fluctuations on nanometer scale, l =Vτ
_CP
, increases markedly below the intermediate temperature T*=560 K, indicating the start of a rapid growth in the size of PNRs at T*.