Magnéli phase Ti4O7 powder from carbothermal reduction method: formation, conductivity and optical properties

Magnéli phase Ti₄O₇ was prepared by carbothermal reduction of TiO₂ in vacuum. The products synthesized in different carbon black content and heated temperature were investigated by X-ray diffraction, scanning electron microscopy, and ultraviolet–visible (UV–Vis) spectra of products were tested also. The results show that the pure Ti₄O₇ powder is obtained with carbon black content of 4 wt% at 1,025 °C for 2 h in vacuum, their average particle size and BET surface area are about 6.10 μm and 4.107 m² g^?1, respectively. The resistivity of the samples is up to 0.11 Ω cm, and UV–Vis spectra shows the optical absorption bands cover the full range of visible-light wave lengths and extend into near-infrared region.