Origin of the giant electro-optic Kerr effect in La-doped 75PMN-25PT transparent ceramics

Transparent ceramics of La-doped Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) x /75/25 are prepared, and the ferroelectric domains, dielectric, and ferroelectric properties of x /75/25 are investigated. A double hysteresis loop and small fingerprint domains with uniform distribution observed for 3/75/25 indicate an intermediate ferroelectric state. The dielectric behavior under dc bias and the evolution of the hysteresis loop with increasing electric field for 3/75/25 indicate an electric field-induced phase transition, and it is proposed that the unstable intermediate ferroelectric state which would experience obvious field-induced phase transition is the origin of the giant electro-optic Kerr effect observed in La-doped PMN-PT 3/75/25.