Stoichiometry Effects on the Chemical Ordering and Superconducting Properties in TiZrTaNbNx Refractory High Entropy Nitrides

• Published in: Annalen der Physik Vol. 536; no. 5
• Main Authors: Shu, Rui, Zhang, Xiaofu, Tasnádi, Ferenc, Olovsson, Weine, Rao, Smita G., Greczynski, Grzegorz, Febvrier, Arnaud, Magnuson, Martin, Eklund, Per
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-05-2024
• Subjects: Chemical bonds; Coordination numbers; Electronic structure; Entropy; high‐entropy alloy; magnetron sputtering; Nitrides; Stoichiometry; Superconductivity; Superconductors; Thin films; Transition temperature
• ISSN: 0003-3804; 1521-3889; 1521-3889
• DOI: 10.1002/andp.202300470

High‐entropy materials, an exciting new class of structural materials involving five or more elements, are emerging as unexplored ground for superconductors. Here, the effects of nitrogen stoichiometry are investigated on local chemical structure of TiZrNbTa‐based thin films by various X‐ray‐based techniques. Lattice distortion and short‐range order of a set of TiZrNbTaNx samples, including bond lengths of different atomic pairs and coordination numbers of substituting atoms are quantitatively studied. The maximum superconducting transition temperature Tc is found at 10 K for a near‐stoichiometric (TiZrNbTa)N1.08 film, which is >8 K measured for a metallic TiZrNbTa film. The underlying electronic structure and chemical bonding in these high entropy nitrides thus influence the superconducting macroscopic properties.
High‐entropy materials are unexplored ground for superconductors. The effects of nitrogen stoichiometry on local structure, lattice distortion, and short‐range order of TiZrNbTa‐based thin films are investigated. The maximum superconducting transition temperature Tc is found at 10 K for a near‐stoichiometric (TiZrNbTa)N1.08 film. The underlying electronic structure and chemical bonding in these high entropy nitrides influence the superconducting macroscopic properties.