Design and Discovery of High‐Temperature Superconducting Ternary Hydrides: From High Pressure to Ambient Conditions

ABSTRACT The pursuit of high‐temperature superconductors at ambient pressure represents one of the foremost challenges in contemporary condensed matter physics, particularly within the realm of hydride materials. This review presents recent theoretical breakthroughs and experimental advances in binary/ternary hydrides and boron–carbon/boron–nitrogen clathrates, highlighting their emergence as candidates for superconductivity. We establish an analytical framework examining the critical relationship between hydrogen content, crystal structure, and electron–phonon coupling, illuminating how some ternary systems circumvent the extreme pressure requirements of their binary counterparts through chemical diversity and lattice stabilization. We introduce a new superconducting quality factor that serves as a metric correlating critical temperatures with stability pressures, providing a unified basis for comparative evaluation across material systems. Hydride superconductors achieve elevated transition temperatures through strong electron–phonon coupling facilitated by hydrogen atoms incorporated within metallic lattices or metallic host frameworks, though many require high pressures for stabilization. Boron–carbon/boron–nitrogen compounds serve as hydride substitutes, with clathrates offering exceptional tunability through their cage‐like frameworks, while both systems potentially provide high‐temperature superconductivity under more accessible conditions. We systematically address persistent challenges in thermodynamic stability and critical temperatures, ultimately aiming to accelerate the discovery of practically viable superconducting hydrides and clathrates by establishing clear structure‐property relationships and identifying pathways for future investigation.