S 53 Shein, I. R. First-principles calculations of elastic and electronic properties of tetragonal Th2NiC2 as a parent phase for new superconductors / I. R. Shein, A. L. Ivanovskii // Journal of Alloys and Compounds. - 2013. - Vol. 551. - P338-342 : il. - Bibliogr. : p. 341-342 (36 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): Th2NiC2 -- ELASTIC PROPERTIES -- AB INITIO CALCULATIONS -- INTER-ATOMIC BONDING -- ELECTRONIC PROPERTIES Аннотация: This work reports on the elastic, electronic properties and inter-atomic bonding of the newly discovered superconductor Th2NiC2 as obtained within ab initio calculations. We found that Th2NiC2 is mechanically stable and it will behave as a ductile material exhibiting enhanced elastic anisotropy in shear and a rather low hardness. The inter-atomic bonding in Th2NiC2 is described as an anisotropic mixture of covalent and ionic contributions, where inside [Th2C2] blocks covalent Th–C bonds emerge, and these blocks are bonded with the Ni atomic sheets through directional Ni–C bonds. Additionally, some inter-atomic ionic Th–C interactions occur owing to charge transfer Th → C. Our data reveal that for Th2NiC2 the Fermi level is located in a deep DOS minimum and the experimentally observed increase in TC in the sequence Th2NiC2 → Th1.8Sc0.2NiC2 may be explained by the growth of N(EF). We also speculate that an increase in N(EF) (and, probably, in TC) for Th2NiC2-based materials may be also achieved by an alternative way: by electron doping – for example, by partial substitution of V for Th or Cu for Ni, as well as by partial substitution of N for C with the formation of Th–Ni carbonitrides like Th2NiC2−xNx Полный текст |