Diffractive electro-optics of electrically-induced spatially periodic texture patterns (namely, wide-formed stationary parallel stripes) in planarly-aligned films of the nematic liquid crystal 4-n-pentyl-4-cyanobiphenyl (5CB) is examined under static electric field in view of its practical application. The longitudinal textural domains electrically-induced with well defined threshold and spatial period have flexo-dielectric nature and differ from the usual flexoelectric stripe distortion, as well as from the electroconvective domains of frequency-dependent morphology. The low-voltage-controlled grating effect through the flexo-dielectric domains can be useful for nematic diffractive optics.