High pressure Raman study of DyPO4 at room and low temperatures

The Raman spectra of DyPO4, under variable hydrostatic pressure at room- and low-temperature (110 K), have been studied. Crossing, with increasing pressure, of two modes in the frequency range of the internal-external border, is observed and discussed. At low temperature, the pressure dependence of the three highest-frequency internal modes is monitored, which exhibit a (dω /dP)-slope differing, well beyond the experimental error, from the corresponding room temperature slopes. At room temperature, all the expected modes are observed and are divided in two distinct groups on a ''logarithmic derivative'' vs. ''peak-frequency'' graph. This division is discussed in terms of the internal-external mode-character. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)