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β-Ni(OH)₂; phase transition; infrared absorption; Raman study; high pressure

Infrared absorption and Raman study ofβ-Ni(OH)₂ has been carried out up to 25 GPa and 33 GPa, respectively. The frequency ofA_2u internal antisymmetric stretching O-H mode decreases linearly with pressure at a rate of −0.7 cm⁻1/GPa. The FWHM of this mode increases continuously with pressure and reaches a value of ∼ 120 cm⁻¹ around 25 GPa. There was no discernible change observed in the frequency and width of the symmetric stretchingA_1g O-H Raman mode up to 33 GPa. The constancy of the Raman mode is taken as a signature of the repulsion produced by H-H contacts in this material under pressure. Lack of any discontinuity in these modes suggests that there is no phase transition in this material in the measured pressure range.

Chitra Murli¹ V Sugandhi^{1 2} Nandini Garg¹ Surinder M Sharma¹ S K Sikka¹

1. High Pressure Physics Division, Bhabha Atomic Research Centre, Mumbai - 400 085, India
2. Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai - 400 085, India

Published

March 1998

Manuscript received

4 August 1997