First‐ and second order Raman scattering in Sb and Bi at high pressure

Abstract

Sb and Bi were investigated by high-pressure Raman spectroscopy in their low pressure phases. One-and two-phonon spectra were measured in the stability field of the A7 structure. The optical zone-centre modes of monoclinic Bi-II were obtained for the first time and have been monitored over an extended pressure range. The pressure response of the observed phonon modes, which is qualitatively similar for both substances, is discussed within the context of the anisotropic bonding properties and their gradual lowering under compression. At ambient conditions in both substances the contributions to the temperature shift of both Raman modes due to thermal expansion are much smaller than the explicit contributions. In contrast to Bi-I, there is evidence that in Sb-I both phonon -phonon-and electron -phonon interactions significantly increase with the application of pressure.

Lattice Dynamics Study of Elemental Bismuth under High Pressure

“…In the case of the Bi-I, Bi-II and -Bi, pressure has little effect on the acoustical branches, especially at the vicinity of the Brillouin zone center. In the case of Bi-I, the frequencies of the optical modes around the Brillouin zone center decrease with increasing pressure, meaning that they have negative Grüneisen parameters, in agreement with the prior Raman experiments 58 and our own Raman scattering experiments (see below). For the other phases, the frequencies of the optical modes increase with pressure, as expected for positive Grüneisen parameters.…”

“…43,44 The phonon density of states has been calculated for the Bi-II phase very recently. 45 From the experimental point of view, the study of different Bi phases by Raman spectroscopy have already been performed for the low-pressure phases Bi-I [55][56][57][58] and Bi-II. 58 H. Olijnyk et al 58 measured for the first time the Raman spectrum of Bi-II at pressure up to 2.7 GPa, two peaks were observed around 40 cm -1 and 80 cm -1 .…”

High-Pressure Studies of Bi2S3

“…39 Even though the low-frequency A g (1) mode of Bi 2 S 3 lies suspiciously close with the A 1g band of Bi−I, the two features exhibit opposite pressure dependence. 39 In addition, Bi can also oxidize and form the a-Bi 2 O 3 phase under laser irradiation. 51 Given, however, that the strongest Raman features of a-Bi 2 O 3 reside in the 300−500 cm −1 frequency range, 53 we can also exclude its presence in our Raman spectra (Figure 5a).…”

Spectroscopic Investigations of Bourdichon Miniatures: Masterpieces of Light and Color

“…This band is identified with the first overtone band of the A 1g fundamental of bismuth (phase I) at 97.9 cm À1 . 49,50 No oxidation of the metallic bismuth was noted with the laser energies employed, as made evident by a complete lack of bands associated with bismite in the spectra of any of the bismuth grains. 51 Bismuthinite is steel-gray with a metallic luster and forms in elongated ''needle-like'' crystals, often with an acicular habit.…”