*Colóquio ministrado em inglês.
**Este colóquio faz parte da programação do Curso de Verão 2025 do IFUSP.
During the 20th century, the formation of compounds between metals or nonmetals and hydrogen was thought to be limited to covalent and molecular-ionic compounds with a composition determined by the element's usual valence. For example, calcium forms the hydride CaH2 with a maximum hydrogen content of 2, and lanthanum forms LaH3, with a maximum H-content of 3. The record for the atomic hydrogen content was held by the CH4 molecule, which is critical for energy industry. Numerous attempts to build a hydrogen battery using lithium, magnesium, nickel etc. hydrides have still not reached the level of efficiency that the methane molecule has. But at high pressure of hundreds of thousands and millions of atmospheres, the situation changes dramatically. Many metals react with hydrogen to form stable polyhydrides containing four (ThH4), six (YH6), eight (UH8), nine (PrH9), ten (CeH10), twelve (BaH12), or even more hydrogen atoms per each metal atom. In 2015, the discovery of superconductivity at 200 K in the high-pressure sulfur hydride H3S led to a surge in theoretical and experimental research in the field of polyhydrides. After discovery of superconductivity in LaH10 (Tc = 250 K) in 2018, it was expected that room-temperature superconductivity would be found very soon. However, despite the past 5 years, this has not happened.
Dr. Dmitrii Semenok received his PhD for research on superhydrides in 2022 at Skolkovo Institute of Science and Technology (Skoltech, Russia). He received two MSc degrees in 2018 from Moscow Institute of Physics and Technology (MIPT) and Skoltech after defense of his MS thesis devoted to computer modeling of superconducting hydrides of transition metals, lanthanides and actinides under high pressure. Currently, he holds the position of advanced postdoc at the Center for High Pressure Science & Technology Advanced Research, Beijing, China. Dmitrii has participated in the discovery and study of most of the metal polyhydrides known today, including ThH10, YH6, CeH9, PrH9, NdH9, EuH9, BaH12, SrH22, SnH4, La4H23, (La, Y)H10, (La, Nd)H10 etc.
