Temperature dependent Raman spectra of the ordered and disordered phases of Ag2HgI4 and Cu2HgI4

Abstract

Raman spectra of Ag2HgI4 were collected over the temperature range 8–470 °K. The ordered phase of Ag2HgI4 exhibits strong temperature dependent damping of the 85 cm−1 mode. The reduced Raman spectra of the disordered phases of both Ag2HgI4 and Cu2HgI4 are found to be temperature dependent. This unusual temperature dependence is attributed to the combined influence of anharmonicity, multiphonon processes, and the correlation time for ion hopping. An estimate of the latter was obtained from the line broadening data. Based on polarized scattering data obtained on very small crystals, symmetry assignments are made for some of the Raman bands of Ag2HgI4.

Roles of phonon amplitude and low-energy optical phonons on superionic conduction

“…48 In the Raman spectra of RbAg 4 I 5 , the broadening of the peaks near 20 and 30 cm Ϫ1 appears suddenly at T c . [49][50][51] This is also evidence for the incorporation.…”

Solvent dynamics in a glass-forming liquid from 300K to 3K: What photon echoes can teach us

“…It has been established that this concept of evaluating hydrodynamic and thermodynamic functions of the solvent can be used to describe the solute-solvent coupling [81,82]. The linear character of temperature dependence has been observed in Raman spectra of amorphous metal solids [83], and in IR pumpprobe studies on the temperature-dependent vibrational relaxation times of carbonyls solutes in various liquids [84,85]. Although this evidence is indirect, it indicates that the linear temperature dependence of the vibrational relaxation in the experiments presented here is reasonably realistic.…”

Origin of the low-energy mode in superionic conductors

“…The crystal structure of the ␤ phase has four units with ZB structure under slightly deformed atomic arrangements. [55][56][57] Since this structure allows the possibility for long-range periodicity, we can predict many phonon bands by folding the B zone. The LEO phonon and the many bands are clearly observed at two separated frequency regions.…”

“…The LEO phonon and the many bands are clearly observed at two separated frequency regions. [55][56][57] …”