Spectroscopic evidence of coexistence of clusters based on low (α) and high temperature (β) GeS2 crystalline phases in glassy germanium disulfide matrix

Technologically modified g-GeS
₂
(TiVj) glasses prepared by melt quenching from different temperatures (T
_i
) and with different cooling rates (Vj) were studied using Raman spectroscopy and model calculations. Differential Raman spectra {I
_R
GeS
₂
(T
_i
V
₁
)-I
_R
GeS2(T
₂
V
₁
)} showed the splitting of the main, most intensive wide-band, centered at 340 cm
^-1
. The position of the peaks found in the differential Raman spectra near 340 and 360 cm
^-1
and position of the main vibrational modes in the ordinary Raman spectra of low- and high-temperature crystalline phases (α-, β-GeS2) were found to be in good agreement. Vibrational spectra of 4- and 6-member ring fragments selected from crystalline structure of β-GeS
₂
were also determined using model calculations. Based on rings composed of GeS
₄
tetrahedrons connected by corners and edges the structural interpretation of the vibrational bands of g-GeS
₂
(TiVj) at 360, 370 and 433 cm
^-1
in their Raman spectra was performed. The existence of homopolar Ge-Ge and S-S “defect” bonds in the structure of germanium disulfide glasses was proved by formation of 5-member rings. Formation of fragments of both low- and high-temperature α-, β-GeS
₂
crystalline phases in the structure of g-GeS
₂
(TiVj) glasses indicates the existence of mixed medium-range ordering in g-GeS
₂
.