Oxides over 77 K

This document presents theoretical proposals for achieving room-temperature superconductivity (above 300 K) at ambient pressure by engineering specific oxide materials with controlled oxygen deficiency. Two primary material systems are proposed. The first is an intermetallic electride with the formula (Ti0.8Nb0.2)4O(Ti0.8Nb0.2)4O, conceptualized as a sub-oxide with an anti-perovskite crystal structure. Its predicted high critical temperature (Tc ~ 310 K) is theorized to arise from a combination of an electride state—creating a flat electronic band with high density of states—and strong electron-phonon coupling facilitated by the rattling vibration of isolated oxygen atoms within a heavy metal lattice. Synthesis would require non-equilibrium techniques like rapid quenching to stabilize this metastable structure. The second proposal focuses on modifying existing high-temperature superconductors. It suggests that introducing a controlled oxygen deficit (δ≈0.2−0.3δ≈0.2−0.3) in the reservoir layers of a triple-layer cuprate (Bi22Sr22Ca22Cu33O10−δ10−δ) or in layered nickelates (e.g., LaNiO2−δ2−δ) could enhance Tc to room temperature. The proposed mechanism involves amplifying the proximity effect between superconducting planes, stabilizing a "nodal metallic" state with a large persistent energy gap, and modifying the phonon spectrum to reinforce Cooper pair coupling. Both proposals are theoretical and emphasize the critical role of precise, non-stoichiometric oxygen control through non-equilibrium or reducing-atmosphere synthesis. Key challenges identified include achieving reproducible material synthesis, ensuring thermodynamic metastability, and requiring experimental validation of the proposed superconducting properties.