Chemists from Moscow State University have discovered new semiconductors from rhenium, gallium and germanium. These compounds - intermetallic compounds - can be used in microelectronics. This was reported by Inorganic Chemistry and Chemical Communications. The study was supported by the Russian Science Foundation .
Scientists call intermetallic compounds metallic compounds whose crystalline structure does not repeat the structures of their constituent metals. In this they differ from alloys. Researchers were interested in the presence of completely different properties in intermetallic compounds, which allow them to be conductors, insulators, superconductors, magnets, and even substances with a shape memory, such as nitinol, consisting of nickel and titanium.
Special attention of chemists was attracted by intermetallic compounds with semiconductor and thermoelectric properties. These rare compounds are mainly used to create thermoelectric devices capable of converting thermal energy into electrical energy, and vice versa.
For the synthesis of such compounds, three metals and semimetals were selected as part of the study: rhenium, gallium, and germanium. The existence of these elements was predicted by Dmitry Ivanovich Mendeleev. Researchers have dedicated the publication of their discovery with Mendeleev’s metals to the 150th anniversary of the periodic table, which is celebrated in 2019.
“Employees ... under the guidance of Professor, Doctor of Chemistry Andrei Shevelkov discovered previously unexplored intermetallic compounds in the rhenium-gallium-germanium system,” said the acting Dean of the Faculty of Chemistry of the University, Corresponding Member of the Russian Academy of Sciences Stepan Kalmykov.
In total, scientists discovered four intermetallic compounds, and two of them - ReGaGe2 and ReGa0.4Ge0.6 - devoted separate scientific works. Among the compounds obtained, chemists noted one of the unusual intermetallic compounds, which turned out to be a brittle powdery substance with semiconductor properties. Experts studied the electronic structure of compounds on a supercomputer at Moscow State University.
“According to the results of calculations, we found a strong localization of electron density between certain atoms, which is not typical for most intermetallic compounds, in which usually the electron density is equally distributed between all atoms, as in metals,” commented one of the authors, MSU graduate student Maxim Likhanov.
Further research will focus on related compounds based on other transition metals such as molybdenum, tungsten and tantalum. Moscow chemists also plan to study the thermoelectric properties of new compounds in the high-temperature region.