Electron Microscopic Study of the Substructure of VO₂ due to the Monoclinic to Tetragonal Phase Transformation

Vanadium dioxide has a monoclinic‐tetragonal phase transformation at about 70 °C. This transformation can be induced in an electron microscope during observation, and the boundaries between the monoclinic and tetragonal phases are observed by the diffraction contrast at the interfaces. When the tetragonal phase is transformed into the monoclinic one, the crystal is broken up into domains according to the different modes of transformation. The interfaces between the domains are revealed as fringe patterns in the electron micrographs. The tetragonal‐monoclinic transformation boundaries and the different types of domain boundaries in the monoclinic phase are studied by electron microscopy.