Search

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. more...

The high purity γ-Ti3O5 thin films deposited on single-crystal SiO2 substrates are firstly prepared via sol–gel method combined with hydrogen reduction processing. In this reported work, the influences of reduction of temperature, hydrogen flow rate and holding time on the reduced phases are investigated. The as-prepared materials are characterized by glancing incident angle X-ray diffraction, scanning electron microscopy. Based on the results of single factor and orthogonal tests, the optimum condition for synthesizing high purity Ti3O5 thin films are as follows: the hydrogen gas flow rate is 0.8 L min−1, the reduction temperature is 1150 °C and the holding time is 1 h. Temperature dependence of PXRD patterns and electrical conductivity (σ) variation demonstrates that the temperature of phase transition between monoclinic I2/c crystal structure of γ-Ti3O5 thin film and monoclinic P2/a crystal structure of δ-Ti3O5 thin film was 225 K. The four-point probe test shows that the room-temperature conductivity of γ-Ti3O5 thin film is 202.1 S m−1. more...

λ-Ti3O5 is an intriguing phase-transition material that has been proposed to be metastable and has emerged at room temperature only in the form of nanocrystals. In this work, λ-Ti3O5 was stabilized to room temperature in the form of microcrystals by aluminum (Al)-ion doping. Al entered the Ti3O5 lattice in the substitutional mode, which reduced the threshold temperature (Tc) of the β-λ phase transition in Ti3O5 and maintained a λ-phase Ti3O5 at room temperature. Al doping caused a significant decrease in resistivity of Ti3O5, which corresponds to a semiconductor-metal transition that is induced by Al-ion doping. We have developed a mechanism to fabricate λ-Ti3O5 by ion doping and have provided a fundamental foundation for a more available application of λ-Ti3O5 in smart optoelectronic devices. more...