June 25, 2007

Practical route to room temperature superconductors

Here is a pdf of a paper "Route to Room-Temperature Superconductivity from a Practical Point of View" by A. Mourachkine of the University of Cambridge

This chapter presents analysis of experimental data which allow one to draw a conclusion about components and the structure of a potential room-temperature superconductor. The two essential components of a roomtemperature superconductor are large organic molecules (polymers, tissues) and atoms/molecules which are magnetic in the intercalated state. This conclusion is fully based on experimental facts known today, and does not require any assumptions about the mechanism of room-temperature superconductivity. This, however, does not mean that to synthesize a room-temperature superconductor is an easy task.

From a technical point of view, superconductors only become useful when they are operated well below their critical temperature—one-half to two-third of that temperature provides a rule of thumb. Therefore, for an engineer, a room-temperature superconductor would be a compound whose resistance disappears somewhere above 450 K. Such a material could actually be used at room temperature for large-scale applications. At the same time, Tc ∼ 350 K can already be useful for small-scale (low-power) applications. Consequently, unless specified, the expression “a room-temperature superconductor” will further be used to imply a superconductor having a critical temperature Tc ≥ 350 K.

The benefits [of room temperature superconductors] would range from minor improvements in existing technology to revolutionary upheavals. All devices made from the room-temperature superconductor will be reasonably cheap since its use would not involve cooling cost. Energy savings from many sources would add up to a reduced dependence on conventional power plants. Compact superconducting cables would replace unsightly power lines and revolutionize the electrical power industry. A world with room-temperature superconductivity would unquestionably be a cleaner world and a quieter world. Compact superconducting motors would replace many noisy, polluting engines. Advance transportation systems would lessen our demands on the automobile. Superconducting magnetic energy storage would become commonplace. Computers would be based on compact Josephson junctions. Thanks to the high-frequency, high-sensitivity operation of superconductive electronics, mobile phones would be so compact that could be made in the form of an earring. SQUID (Superconducting QUantum Interference Device) sensors would become ubiquitous in many areas of technology and medicine. Room-temperature superconductivity would undoubtedly trigger a revolution of scientific imagination. The effects of room-temperature superconductivity would be felt throughout society, including children who might well grow up playing with superconducting toys.

According to the first principle of superconductivity, superconductivity requires electron pairing. Indeed, the electron pairing is the keystone of superconductivity.
Therefore, in quest of compounds that superconduct above room temperature, one should first look at materials which tolerate the presence of Cooper pairs at high temperatures. Fortunately, it is known already for some time that the Cooper pairs exist in some organic compounds at and above room temperature.