Electrooptic effect for cold neutrons in photorefractive materials

First experimental evidence for the existence of an electrooptic effect fur cold neutrons in (LiNbO3)-Li-7 is reported and discussed. The effect is ba sed on the fact that in certain photorefractive crystals a light-induced sp ace-charge field can be generated which causes a modulation of the density via the inverse piezoelectric effect. From such density structures, induced by the internal electric field, cold neutrons can be diffracted.