Recently, a Chinese research team achieved a major breakthrough in rare earth chemistry. Researchers from Soochow University, in collaboration with those from Tsinghua University, successfully synthesized a rare earth triple-bond compound, long considered a "forbidden zone" in scientific research. This achievement challenges traditional understanding of rare earth elements' bonding capabilities, with the findings published in Nature Chemistry.
Rare earth elements include scandium, yttrium, and the 15 lanthanide elements. Due to their unique magnetic, optical, electrical, and catalytic properties, rare earth compounds have significant applications across various fields. For instance, neodymium-iron-boron rare earth permanent magnets, with their high magnetic energy product and stability, are core components in motors (for new energy vehicles, household appliances, and wind power) and zoom motors (for phone cameras). Adding rare earth oxides like Y?O? and La?O? enhances the sintering performance of structural ceramics such as Al?O?, Si?N?, and ZrO?, improving strength and heat resistance. Erbium-doped fiber amplifiers (EDFAs) are essential in optical communication devices. Cerium oxide serves as an additive in the glass industry, a material for plate glass grinding, and an anti-UV agent in cosmetics.
In rare earth compounds, chemical bonds are predominantly ionic, stemming from the elements' large atomic radii and low electronegativity, which favor electrostatic interactions. The contraction of the 4f orbital and the high energy of the 5d orbital limit rare earth elements' ability to participate in orbital hybridization, significantly restricting their capacity to form covalent bonds, especially multiple bonds.
According to the study, China research team innovatively utilized the spatial confinement and protective effects of fullerene molecular cages, employing an improved arc discharge technique to successfully prepare the first triple-bond compound of cerium and carbon encapsulated in a fullerene. This achievement stabilizes the cerium-carbon triple bond. The research not only opens new avenues in the study of rare earth chemical bonds but also holds significant implications for the preparation of rare earth compounds and new materials.
