Field-induced sharp ferroelectric phase transition was observed in Sr0.66Ba
0.34Nb2O6 single crystals. The peaks of the real and imaginary parts of die
lectric permittivity arise upon cooling under weak dc bias electric fields
and subsequently heating under zero fields or upon cooling under zero field
s and subsequently heating under weak electric fields. The applied electric
field cancels the random fields that destroy the phase transition and give
rise to low temperature domain state if E=0. These results strongly sugges
t that the SBN system belongs to the random field Ising universality class,
a rare case among structural phase transitions. (C) 2001 American Institut
e of Physics.