Superconductivity is a set of physical properties observed in superconductors: materials where electrical resistance vanishes and magnetic fields are expelled from the material. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered, even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.
High-temperature superconductivity is superconductivity in materials with a critical temperature above 77 K, the boiling point of liquid nitrogen. They are only "high-temperature" relative to previously known superconductors, which function at colder temperatures, close to absolute zero. The "high temperatures" are still far below ambient, and therefore require cooling. The first breakthrough of high-temperature superconductor was discovered in 1986 by IBM researchers Georg Bednorz and K. Alex Müller. Although the critical temperature is around 35.1 K, this new type of superconductor was readily modified by Ching-Wu Chu to make the first high-temperature superconductor with critical temperature 93 K. Bednorz and Müller were awarded the Nobel Prize in Physics in 1987 "for their important break-through in the discovery of superconductivity in ceramic materials". Most high-Tc materials are type-II superconductors.
Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington.
Palladium hydride is palladium metal with hydrogen within its crystal lattice. Despite its name, it is not an ionic hydride but rather an alloy of palladium with metallic hydrogen that can be written PdHx. At room temperature, palladium hydrides may contain two crystalline phases, α and β. Pure α-phase exists at x < 0.017 while pure β-phase exists at x > 0.58; intermediate values of x correspond to α–β mixtures.
A room-temperature superconductor is a hypothetical material capable of displaying superconductivity above 0 °C, operating temperatures which are commonly encountered in everyday settings. As of 2023, the material with the highest accepted superconducting temperature was highly pressurized lanthanum decahydride, whose transition temperature is approximately 250 K (−23 °C) at 200 GPa.
The Max Planck Institute for Solid State Research was founded in 1969 and is one of the 82 Max Planck Institutes of the Max Planck Society. It is located on a campus in Stuttgart, together with the Max Planck Institute for Intelligent Systems.
Johannes Georg Bednorz is a German physicist who, together with K. Alex Müller, discovered high-temperature superconductivity in ceramics, for which they shared the 1987 Nobel Prize in Physics.
An iron hydride is a chemical system which contains iron and hydrogen in some associated form.
Artem R. Oganov is a Russian theoretical crystallographer, mineralogist, chemist, physicist, and materials scientist. He is known mostly for his works on computational materials discovery and crystal structure prediction, studies of matter at extreme conditions, including matter of planetary interiors.
Yttrium hydride is a compound of hydrogen and yttrium. It is considered to be a part of the class of rare-earth metal hydrides. It exists in several forms, the most common being a metallic compound with formula YH2. YH2 has a face-centred cubic structure, and is a metallic compound. Under great pressure, extra hydrogen can combine to yield an insulator with a hexagonal structure, with a formula close to YH3. Hexagonal YH3 has a band gap of 2.6 eV. Under pressure of 12 GPa YH3 transforms to an intermediate state, and when the pressure increases to 22 GPa another metallic face-centred cubic phase is formed.
Russell Julian Hemley is an American geophysicist, solid-state physicist, and physical chemist. Hemley is especially notable for his work in the theoretical prediction and experimental observation of near room-temperature superconductivity in lanthanum decahydride under high pressure.
A polyhydride or superhydride is a compound that contains an abnormally large amount of hydrogen. This can be described as high hydrogen stoichiometry. Examples include iron pentahydride FeH5, LiH6, and LiH7. By contrast, the more well known lithium hydride only has one hydrogen atom.
Lanthanum decahydride is a polyhydride or superhydride compound of lanthanum and hydrogen (LaH10) that has shown evidence of being a high-temperature superconductor. It was the first metal superhydride to be theoretically predicted, synthesized, and experimentally confirmed to superconduct at near room-temperatures. It has a superconducting transition temperature TC around 250 K (−23 °C; −10 °F) at a pressure of 150 gigapascals (22×10^6 psi), and its synthesis required pressures above approximately 160 gigapascals (23×10^6 psi).
An oxyhydride is a mixed anion compound containing both oxide O2− and hydride ions H−. These compounds may be unexpected as the hydrogen and oxygen could be expected to react to form water. But if the metals making up the cations are electropositive enough, and the conditions are reducing enough, solid materials can be made that combine hydrogen and oxygen in the negative ion role.
In chemistry, a hydridonitride is a chemical compound that contains both hydride and nitride ions. These inorganic compounds are distinct from inorganic amides and imides as the hydrogen does not share a bond with nitrogen, and usually contain a larger proportion of metals.
Metallization pressure is the pressure required for a non-metallic chemical element to become a metal. Every material is predicted to turn into a metal if the pressure is high enough, and temperature low enough. Some of these pressures are beyond the reach of diamond anvil cells, and are thus theoretical predictions. Neon has the highest metallization pressure for any element.
Carbonaceous sulfur hydride (CSH) is a potential superconductor that was announced in October 2020 by the lab of Ranga Dias at the University of Rochester, in a Nature paper that was later retracted. It was reported to have a superconducting transition temperature of 15 °C (59 °F) at a pressure of 267 gigapascals (GPa), which would have made it the highest-temperature superconductor discovered. The paper faced criticism due to its non-standard data analysis calling into question its conclusions, and in September 2022 it was retracted by Nature. In July 2023 a second paper by the authors was retracted from Physical Review Letters due to suspected data fabrication, and in September 2023 a third paper by the authors about N-doped lutetium hydride was retracted from Nature.
Eva Dagmara Zurek is a theoretical chemist, solid-state physicist and materials scientist. As a professor of chemistry at the University at Buffalo, Zurek studies the electronic structure, properties, and reactivity of a wide variety of materials using quantum mechanical calculations. She is interested in high pressure science, superhard, superconducting, quantum and planetary materials, catalysis, as well as solvated electrons and electrides. She develops algorithms to predict the structures of crystals, interfaces them with machine learning models, and applies them in materials discovery.
Ranga P. Dias is a researcher with a primary interest in condensed matter physics. He was an assistant professor in the departments of Mechanical Engineering and Physics and Astronomy at the University of Rochester (UR), and a scientist at the UR Laboratory for Laser Energetics. As of November 19, 2024, he was no longer employed at UR.
