In the present study, the electronic, phonon, and electron-phonon interactions of titanium suboxide structures including TiO, ${\mathrm{Ti}}_2{\mathrm{O}}_3,$ ${\mathrm{Ti}}_3{\mathrm{O}}_5,$ ${\mathrm{Ti}}_4{\mathrm{O}}_7,$ and ${\mathrm{Ti}}_5{\mathrm{O}}_9$ were investigated in the framework of density-functional theory. The mechanism of superconductivity in these materials seems to be phonon mediated, probably with participation of paramagnetic spin fluctuations. The influence of pressure on the superconducting transition temperature $\left(T_C\right)$ of cubic TiO and ${\mathrm{Ti}}_4{\mathrm{O}}_7$ could be explained by this mechanism. Our calculations predict a low $T_{\mathrm{C}}$ of ∼3.5 K for ${\mathrm{Ti}}_5{\mathrm{O}}_9$. It implies that ${\mathrm{Ti}}_5{\mathrm{O}}_9$ would be a superconductor lying in the weak coupling regime.

• Received 16 August 2021
• Revised 9 November 2021
• Accepted 9 November 2021

DOI:https://doi.org/10.1103/PhysRevB.104.224101