The Effect of Magneli phase Ti4O7 as an additive in air-sintered TiO2 ceramics

Magneli phases are an important class of transition metal oxides widely utilized in fields such as batteries, electrocatalysis, and photocatalysis. However, there are no reports on the use of Magneli phases as additives in ceramic sintering. In order to explore the impact of the Magneli phase as an additive on the sintering process, self-made Magneli phase Ti4O7 powder was added to the graded mixture of titanium dioxide (TiO2) coarse powder and nanopowder, and sintered under atmospheric conditions in this study. The sintering characteristics, microstructure, and mechanical properties of TiO2 ceramics with different content of Ti4O7 were characterized. The results revealed that the addition of Ti4O7 contributed to the reduction of the densification temperature of TiO2 ceramics. Compared to the undoped sample, the addition of 1 wt% Ti4O7 powder significantly improved the flexural strength and Vickers hardness of TiO2 ceramics by 13.5% and 24.8%. According to the results of thermal analysis, UV-Vis-NIR, and XPS, the mechanism of Ti4O7 in the sintering process of TiO2 ceramics under atmospheric conditions was systematically discussed. This work not only obtained TiO2 ceramics with improved performance but also showed the tremendous potential of Magneli phases in the field of ceramic sintering.