SPECTROSCOPIC STUDY OF BETA-NI(OH)(2) UNDER PRESSURE

Infrared absorption and Raman study of beta-Ni(OH)(2) has been carried out up to 25 GPa and 33 GPa, respectively. The frequency of A(2u) int ernal antisymmetric stretching O-H mode decreases linearly with pressu re at a rate of -0.7 cm(-1)/GPa. The FWHM of this mode increases conti nuously with pressure and reaches a value of similar to 120 cm(-1) aro und 25 GPa. There was no discernible change observed in the frequency and width of the symmetric stretching A(1g) O-H Raman mode up to 33 GP a. The constancy of the Raman mode is taken as a signature of the repu lsion produced by H-H contacts in this material under pressure. Lack o f any discontinuity in these modes suggests that there is no phase tra nsition in this material in the measured pressure range.