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.
Local structure investigation of β-Ni(OH)2 under pressure using combined Raman and Ni K-edge extended x-ray absorption fine structure studies / C. Marini, B. Joseph, S. Caramazza, F. Capitani, M. Bendele, I. Kantor, P. Lotti, O. Mathon, S. Pascarelli, P. Postorino. - In: HIGH PRESSURE RESEARCH. - ISSN 0895-7959. - 37:1(2017 Jan), pp. 1-10. [10.1080/08957959.2016.1269174]
Local structure investigation of β-Ni(OH)2 under pressure using combined Raman and Ni K-edge extended x-ray absorption fine structure studies
P. Lotti;
2017
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.File | Dimensione | Formato | |
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