The crystal structures of Ti2O3, a semiconductor,and (Ti0.900V0.100)2O3, a semimetal

The crystal structures of the semiconductor Ti₂O₃ and the semimetal (Ti_0.900V_0.100)₂O₃ were determined from X-ray diffraction data collected from single crystals. The compounds are isostructural with Al₂O₃ of rhombohedral unit cell dimensions of a = 5.4325(8) Å and α = 56.75(1)° for Ti₂O₃, and a = 5.4692(8) Å and α = 55.63(1)° for the doped system. The effect of substitution of V⁺³ is to increase the metal-metal distance across the shared octahedral face from 2.579 Å in Ti₂O₃ to 2.658 Å in (Ti_0.900V_0.100)₂O₃, while decreasing the metal-metal distance across the shared octahedral edge from 2.997 to 2.968 Å. The metal-oxygen distances exhibit only small changes. These structural changes are consistent with the band theory proposed by Van Zandt, Honig, and Goodenough (9) to explain changes in electrical and other properties with increasing vanadium content in (Ti_1?xV_x)₂O₃.