Unified Theory of Low and High-Temperature Superconductivity

Superconductors hold immense potential for various applications and could have a profound impact on humanity. Despite extensive research, a room-temperature superconductor of practical value has yet to be achieved. The BCS theory cannot account for high-temperature superconductors. This issue may arise from the traditional model inaccurately attributing resistance to particle collisions of electron flow in conductors. This research proposes an alternative theory. The electrical resistance state of the same substance can vary from being an insulator to a conductor or a superconductor at different pressures and temperatures. These states are primarily determined by electron tunnels, which develop through molecular interactions. Within electron tunnels, electrons can move across molecules at the same potential level, resulting in currents. In conductors, electrons are confined to their molecules below the energy level of electron tunnels; energy is needed to elevate them into these tunnels to produce currents, causing electrical resistance. The resistance of a conductor can be decreased by compressing molecular spacing, as it minimizes the gap between valence orbitals and electron tunnels. With additional pressures, the gap can be further reduced to zero in superconductors, resulting in the intersection between valence orbitals and electron tunnels. Therefore, electrons can enter the tunnels without lifting energy, leading to zero resistance. This explains the inverse relationship between resistivity and pressure and why many high-temperature superconductors are achieved under high pressures. Molecular spacing decreases at low temperatures, as electrons move to lower orbitals. It reduces the pressure between molecules, mimicking the compressing effect. This elucidates the correlation between resistivity and temperature and why conventional superconductors are observed at low temperatures. In insulators, the electron tunnels are disconnected due to the large molecular spacing. This spacing can be reduced with high pressures, thereby joining these tunnels. This is why some ceramics become superconductors under high pressures. This theory unifies insulators, conductors, and superconductors as dynamic resistance states of matter at different pressures and temperatures. The distinction between these states lies in the extent and connectivity of electron tunnels and the gaps between the tunnels and valence orbitals. A crucial insight from this theory for synthesizing room-temperature superconductors is the need to compress molecular distances. The significant barrier is the repulsion between molecules. Overcoming this repulsion with external pressures, as currently done to achieve most high-temperature superconductors, is impractical for most applications. An alternative approach may involve engineering molecular structures to leverage molecular attractions between certain molecules to overcome the repulsion.