The grain boundary of nanocrystalline films was investigated by using the X-ray absorption fine structure technique. With the advantage of a predominant grain boundary volume fraction, the grain boundary structure was found to be neither simply gas-like nor similar to that of a coarse-grained phase, but instead experienced a transition from a modestly ordered innermost coordination shell around centered atoms, to a partly disordered second coordination shell, and then to completely disordered higher coordination shells.

Structure of Grain Boundaries in Nanostructured ZnO. Z.Wu, Y.Zhou, X.Zhang, S.Wei, D.Chen: Applied Physics Letters, 2004, 84[22], 4442-4