Dynamical Bond Formation in KNi2Se2. Issue 15 (20th April 2022)

• Record Type: Journal Article
• Authors: Neilson, James R.; Fry‐Petit, Allyson M.; Drichko, Natalia; Stone, Matthew B.; Llobet, Anna; Balasubramanian, Mahalingam; Suchomel, Matthew R.; McQueen, Tyrel M.
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 648:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-20
• Subjects: emphansis -- metal-metal bonding -- pair distribution function -- raman scattering -- diffraction; Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.202200042
• Languages: English
• ISSNs: 0044-2313

Abstract

Abstract: Emphanisis, or the appearance out of nothing, has been used to describe the phenomena of spontaneous atom off‐centering and dipole formation at elevated temperatures in lead chalcogenides. Here, we provide spectroscopic evidence of spontaneous formation of metal‐metal bonds above T ∼50 K in the layered metal KNi2 Se2 . These bonds form zig‐zag chains that lower the local symmetry from tetragonal to monoclinic. Energy‐resolved pair distribution function measurements exclude a pure phonon origin of our observations, and instead imply the existence of extra, slowly fluctuating, Ni−Ni bonds above T =50 K. Density functional theory calculations support this lower symmetry configuration as an instability of tetragonal KNi2 Se2 . We thus demonstrate that the phenomena of emphansis is not limited to local electric dipole formation, but can also be driven by the formation of metal‐metal bonds. Abstract :