An STM study of the initial oxidation of single-crystalline zirconium surfaces

► We present a STM study of the microstructural development of thin ZrO2 films on Zr as grown by thermal oxidation. ► Oxidation proceeds by the fast formation of a dense arrangement of oxide clusters. ► Agglomeration of oxide clusters proceeds with increasing oxidation temperature/time. ► Long-range atomic order develops in these large oxide agglomerates.