We present concrete evidence for the formation of ferroelectric domain
gratings induced by photorefractive space-charge electric fields in t
op-seeded solution-grown barium titanate crystals. These domain gratin
gs are not destroyed by light and, by applying a field, can be reconve
rted into photorefractive gratings that diffract much more light than
the photorefractive gratings that create them, as much as 67% of an in
cident beam.