  Eu modified Na1/2Bi1/2TiO3 (NBT) was investigated for electric-field induced
Eu+3 photoluminescence (PL) and structural changes. Detailed analysis revealed
that below a critical Eu composition electric field irreversibly suppresses the
structural heterogeneity inherent of the host matrix NBT and brings about a
long range ferroelectric state with rhombohedral (R3c) distortion. PL study
revealed that structural disorder on the nano-scale opens new channels of
radiative transitions which can be suppressed by electric field. This study
suggests that Eu+3 luminescence can be used to probe the relative degree of
field induced structural ordering in relaxor ferroelectrics and also in high
performance piezoelectric alloys where electric field couples very strongly
with the lattice and structural degrees of freedom.
