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Temperature and Pressure Dependence of Raman Scattering in Amorphous GeS 2
Author(s) -
Perakis A.,
Kotsalas I. P.,
Pavlatou E. A.,
Raptis C.
Publication year - 1999
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199901)211:1<421::aid-pssb421>3.0.co;2-f
Subject(s) - raman spectroscopy , amorphous solid , raman scattering , materials science , opacity , phase (matter) , ambient pressure , melting point , condensed matter physics , tetrahedron , scattering , molecular physics , optics , crystallography , chemistry , thermodynamics , composite material , physics , organic chemistry
The evolution of the Raman spectrum of amorphous GeS 2 is reported over wide temperature (300 to 1075 K) and pressure (0 to 10.8 GPa) ranges. The temperature dependence shows that a‐GeS 2 turns gradually crystalline above T g , first to the 3D‐phase and then to the layered (2D)‐phase, with the latter one being retained up to the melting point and upon normal cooling to 300 K. The evolution of the A c 1 companion band of a‐GeS 2 into the crystalline phases indicates that this band is due to the symmetric stretch of S atoms in bridges of edge‐sharing Ge(S 1/2 ) 4 tetrahedra. The Raman bands of a‐GeS 2 harden with increasing pressure, indicating a continuous decrease of the Ge–S bond length, while the material remains amorphous throughout the pressure range. Above 10 GPa, the material becomes almost opaque, thus making difficult the observation of Raman scattering. All these pressure induced effects are reversible after bringing the sample to ambient pressure.