Superconductivity typically demands very low temperatures, requiring liquid helium or similar means to bring the temperature down to where electrical resistance is zero. Even the high-temperature superconductors have yet to come anywhere close to room temperature, topping out at approximately 110 degrees C above absolute zero (which is still 163 degrees below freezing). However, physicists have postulated that certain hydrogen-rich compounds may exhibit significantly higher transition temperatures.
A new simulation by Hui Wang et al. suggests that a calcium hydride compound (CaH6) could have a critical transition temperature as high as 235 K (-38° C). The catch: the material must be subjected to pressures of approximately 150 gigapascals (150 GPa, or approximately 1.5 million atmospheres), pressures more typical of geological processes. The key to the pressure-driven transformation is the formation of a clathrate, or cage-like structure in the crystal lattice. The predicted electronic structure may allow the coupling between vibrations of the atoms (phonons) and electrons, leading to superconductivity.
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from Ars Technica