The lattice location of three rare‐earth ions (Pr3+, Ho3+, Yb3+) in LiNbO3is investigated using Rutherford backscattering spectrometry/channeling techniques. All of them are found to occupy the Li+octahedron but shifted from the Li+regular position by different amounts (−0.45 A˚ for Pr3+, −0.38 A˚ for Ho3+, and −0.3 A˚ for Yb3+) as previously reported for other rare‐earth ions. The amount of displacement is directly related to the variation of the ionic radius of the rare‐earth ion, oppositely to transition metal ions which are not shifted. A simple model based on electronic configuration is given to account for this behavior. ©1995 American Institute of Physics.