Abstract
Domain patterns visible in reflected polarized light on surfaces of vanadium dioxide are described. Several x‐ray reflection techniques and analysis of the reflected polarized light are used to investigate the domain structure of the low‐temperature monoclinic phase of VO2. This is shown to be due to transformation twinning in which the monoclinic unit cell is rotated into successive ninety‐degree positions about the a‐monoclinic axis.