The hot‐forging technique was used to obtain both the n = 2 (Sr3Ti2O7) and n = ∞ (SrTiO3) members of Ruddlesden‐Popper phase Srn+1TinO3n+1. Pure phase and high density (>95% theoretical) materials were achieved using this technique. These polycrystalline samples were irradiated with 200 keV He ions to a fluence of 2×1021 ion/m2 (corresponding to a peak dose at 5 dpa) at room temperature to study radiation damage effects. Microstructural investigation on pristine and irradiated samples was performed using grazing incidence X‐ray diffraction (GIXRD) and transmission electron microscopy (TEM). Three phenomena are revealed upon comparing prisXtine versus irradiated samples. First, both compounds interplanar lattice spacings increased after irradiation. Second, peak broadening possibly suggests incredibly small grain due to irradiation. Third, experiment results revealed an amorphization in the irradiated Sr3Ti2O7, while no amorphization was observed in irradiated SrTiO3. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)