X-ray diffraction study of metallic VO2

Refinement of the crystal structure of V${\mathrm{O}}_2$ at 360 and 470 K in the metallic rutile phase shows that both the vanadium and oxygen thermal displacements are larger than those found in rutile phases of Ti${\mathrm{O}}_2$ and Cr${\mathrm{O}}_2$ or monoclinic phases of V${\mathrm{O}}_2$ or ${\mathrm{V}}_{0.976}$ ${\mathrm{Cr}}_{0.024}$ ${\mathrm{O}}_2$. The vanadium-vanadium distance along the rutile ${\mathrm{V}}_{0.976}{\mathrm{Cr}}_{0.024}{\mathrm{O}}_2$ axis is anomalously short when compared with neighboring rutile phases while the other nearest-neighbor metal-metal and metal-oxygen distances vary smoothly across the series. A comparison of Debye temperatures calculated from heat-capacity and x-ray data suggests the presence of low-lying vibrational modes in metallic V${\mathrm{O}}_2$.