X-ray diffraction of polycrystalline Ti4O7

X-ray powder diffraction of powder and sintered EBONEX (nominally Ti₄O₇) is reported. The patterns show clearly the existance of another Magneli phase (Ti₅O₉) in both forms of the material. Its concentration was determined from the integrated intensity ratios of the (101) vs. (101) the (121) vs. (121) and the (206) vs. (208) lines of Ti₄O₇ vs. Ti₅O₉, respectively. For samples taken from one batch, the powder form of EBONEX contains ca. 25±5 a% of Ti₅O₉ while the sintered form contains about twice as much. Samples from another batch, prepared under improved process control, showed ca. 10a% of Ti₅O₉ in the powder form of the material. Both forms contain small traces of other phases as well, e.g., Ti₃O₅ in the powder and Ti₆O₁₁ in the sintered material. These results agree with recently reported ESR line-broadening measurements. We also observed aging effects such as gradual oxidation in the sintered material.