Temperature-induced structural and electronic phase transitions in λ-phase $T{i}_3{O}_5$

We investigated changes in the structural and electronic properties of single-crystalline $T{i}_3{O}_5$ films across temperature-induced phase transitions. Based on resistivity and synchrotron x-ray diffraction measurements, we determined the phase diagram of $T{i}_3{O}_5$. The characteristic properties of $T{i}_3{O}_5$ were classified into three temperature regions: the insulating λ phase at $T$ ≤ 350 K, the conductive λ phase at 350 K ≤ $T$ ≤ 460 K via the metal-insulator transition, and the metallic α phase at $T$ ≥ 460 K. Detailed crystallographic analysis revealed that the monoclinic λ phase exhibited a second-order structural phase transition to the orthorhombic α phase, accompanied by a gradual deformation of the monoclinic angle. These results suggest that unusual temperature-induced changes in $T{i}_3{O}_5$ originate from similar atomic conformations of the λ and α phases. Our findings provide guidelines for controlling multiple phase transitions in $T{i}_3{O}_5$ polymorphs using external stimuli, which is crucial for optoelectronic and heat-storage applications of $T{i}_3{O}_5$.