Local structure investigation of β-Ni(OH)2 under pressure using combined Raman and Ni K-edge extended x-ray absorption fine structure studies. Issue 1 (2nd January 2017)

• Record Type: Journal Article
• Authors: Marini, C.; Joseph, B.; Caramazza, S.; Capitani, F.; Bendele, M.; Kantor, I.; Lotti, P.; Mathon, O.; Pascarelli, S.; Postorino, P.
• Is Part Of: High pressure research. Volume 37:Issue 1(2017)
• Page Start: 1
• Page End: 10
• Publication Date: 2017-01-02
• Subjects: High pressure -- RAMAN -- EXAFS; High pressure (Science) -- Periodicals; High pressure (Technology) -- Periodicals; 536.41
• DOI: 10.1080/08957959.2016.1269174
• Languages: English
• ISSNs: 0895-7959

Abstract

ABSTRACT: We present a combined high pressure Ni K-edge x-ray absorption and Raman spectroscopic investigation of β-Ni(OH) 2 . Extended x-ray absorption fine structure analysis reveals a progressive shrinking of the Ni–O and Ni–Ni bond distances with pressure. As pressure is increased, Raman data show a continuous hardening of the phonon modes associated with the vibration of Ni–O sublattice, whereas a systematic frequency softening is displayed by the hydroxyl (O–H) symmetric stretching mode. This contrasting behavior implies a gradual development of a lattice instability with pressure in nickel hydroxide. Under pressure hydrogen bonds become increasingly unstable mainly due to the displacement of H atoms around the Ni–O axis inducing a local-lattice instability may explain the structural, Raman and x-ray absorption results.