  We show that an electrically soft ferroelectric host can be used to tune the
photoluminescence (PL) response of rare-earth emitter ions by external electric
field. The proof of this concept is demonstrated by changing the PL response of
Eu+3 ion by electric field on a model system Eu-doped
0.94Na1/2Bi1/2TiO3-0.06BaTiO3. We also show that new channels of radiative
transitions, forbidden otherwise, open up due to positional disorder in the
system, which can as well be tuned by electric field.
