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Holographic gratings were recorded in a ferroelectric bismuth titanate crystal. Refractive index as well as absorption gratings contribute to the recording process with modulation amplitudes ⌬nϭ1.8ϫ10 Ϫ5 and ⌬␣ϭ0.8 cm Ϫ1 , respectively. The dominating charge transport mechanism for the formation of the spacecharge field in the crystal is diffusion. The dependence of the photorefractive gain on the writing crossing angle and thus the effective photorefractive charge density of our sample was determined by beam-coupling experiments.