AbstractThe binary Ru4Si3 remained the only compound in its structure type for more than 60 years. Herein, we report the synthesis and crystal structure of the first ternary silicide (Ir4−xCuSi2) in the Ru4Si3-type structure, which can be derived from RuSi by unit cell twinning. According to single-crystal X-ray diffraction, Ir vacancies exist along the twin boundary. Ir4−xCuSi2 exhibits a distorted structure compared to Ru4Si3, as the larger Cu selectively replaces Si on only one of three possible sites, leading to zigzag chains with short Cu–Cu distances. Furthermore, DFT calculations show that the rigid band approximation does not apply to this structure type, but the similarities of electronic structures of the ideal binary and ternary compositions suggest that this structure type can accommodate a large variety of elemental substitutions without a significant change of its electronic structure if a similar valence electron count is maintained, hinting at a potentially rich substitutional chemistry.
The new ternary silicide Lu3Ni11.74(2)Si4 was synthesized from the elements by arc-melting and its crystal structure was determined by the single-crystal X-ray diffraction. The compound crystallizes in the Sc3Ni11Ge4-type: Pearson symbol hP37.2, space group P63/mmc (No. 194), a = 8.0985(16), c = 8.550(2) Å, Z = 2; R = 0.0244, wR = 0.0430 for 244 reflections. The silicide Lu3Ni11.74(2)Si4 is new member of the EuMg5.2-type structure family.
The new ternary silicide Dy3Ni11.83(1)Si3.98(1)was synthesized from the elements by arc-melting and its crystal structure was determined by X-ray single-crystal diffraction. The compound crystallizes in a Sc3Ni11Ge4-type structure: Pearson symbolhP38, space groupP63/mmc(No. 194),a= 8.1990(7),c= 8.6840(7) Å,Z= 2;R= 0.0222, wR= 0.0284 for 365 reflections. The structure belongs to a large family of structures related to the EuMg5.2type, with representatives among ternary aluminides, silicides, germanides,etc.
An ab initio method, based on the plane wave pseudopotential and the generalized gradient approximation (GGA), is performed to investigate the physical properties such as structural, elastic, electronic and bonding properties of newly synthesized Li2RhSi3 and predicted Li2OsSi3 ternary silicide superconductors for the first time. Both of these compounds are mechanically stable and are brittle in nature. They also have good machinability. Electronic band structures reveal that these compounds have metallic characteristics. They possess complex bonding nature (metallic, covalent and ionic). According to theoretical Vickers hardness, Li2RhSi3 is softer than Li2OsSi3.
Crystal and electronic structures of the new ternary silicide Sc12Co41.8Si30.2