Pressure Raman spectra of LiK0.8(NH4)(0.2)SO4

Raman spectra of LiK0.8(NH4)(0.2)SO4 were obtained as a function of applied pressure. The measurements were carried out using a microscope to focus th e light into a spot size of 2 mum, in order to avoid probing a multi-domain sample. With increasing pressure, many of the Raman peaks are shifted towa rds higher wavenumbers. At certain pressures the number of peaks changes an d the (v) over tilde vs P plots are discontinuous. These effects occurring at P = 0.9 and 2.5 GPa were interpreted as structural phase transitions. Th e pressure coefficients are given for modes derived from the pure E-2 and A (LO) symmetries of a-phase. Copyright (C) 2001 John Wiley & Sons, Ltd.