Crystallographic investigations of the phase transition of VO₂

The phase transition of VO₂ was examined by the X-ray method for the single-crystal whiskers of VO_2.00 and VO_2.07. Attention was directed mainly towards the different behaviour in the different specimens at the premonitory stage of the monoclinic tetragonal transition. Appearance of a triclinic twin at this stage in VO_2.07 indicated a larger degree of monoclinic distortion than in VO_2.00.