Phase evolution and formation of λ phase in Ti3O5 induced by magnesium doping

λ-Ti3O5 is a promising phase-transition metal oxide for the application in rewritable data storage, heat storage and smart optoelectronic devices due to its bistable metal-semiconductor transition (MST) characteristics between λ and β phase. However, λ-Ti3O5 is a room-temperature metastable phase and it's synthesis has been a great challenge. This paper presented a magnesium (Mg)-doping strategy for phase control of Ti3O5 to obtain the λ-Ti3O5 via carbothermal reduction method. The results revealed that Mg-doping induced a crystal-structure modification in Ti3O5 by tuning the Mg-doping content. Particularly, it suggested that the phase-transition temperature (Tc) of β–λ was reduced efficiently by increasing the Mg additive amount, and the λ phase was stabilized at room temperature eventually. Electrical resistivity measurement demonstrated a remarkable decrease in resistivity of Ti3O5, indicating a β–λ–α phase evolution induced by Mg-doping. In-situ temperature-dependent XRD was also employed to confirm the phase evolution and phase-transition characteristic of Ti3O5. This work offered considerable insights into a controllable crystal-structure modification for Ti3O5 by a doping strategy and the mechanism to the stabilization of metastable λ-Ti3O5.