An inversion domain boundary (IDB) related to an interstitial stacking layer (ISL) was observed on the {0002} planes of the wurtzite (WZ) structure of tin (Sn)-doped ZnO nanobelts. Quantitative STEM analysis confirmed that the ISL was composed of Sn element. Oxygen related to the ISL was in a triangular coordination as determined by analyzing the electron energy-loss spectra. Expansion of the interplanar spacing along the c-axis of a WZ structure was observed near the IDB while that along the a-axis was constrained. Density functional theory calculations were carried out to elucidate the origin of microstructural evolution. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4788812]