We investigated changes in the structural and electronic properties of single-crystalline $\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$ films across temperature-induced phase transitions. Based on resistivity and synchrotron x-ray diffraction measurements, we determined the phase diagram of $\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$. The characteristic properties of $\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$ 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 $\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$ originate from similar atomic conformations of the λ and α phases. Our findings provide guidelines for controlling multiple phase transitions in $\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$ polymorphs using external stimuli, which is crucial for optoelectronic and heat-storage applications of $\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$.

• Received 19 September 2023
• Accepted 26 February 2024

DOI:https://doi.org/10.1103/PhysRevMaterials.8.035002