Exploration of the Hydrogen Sulfide−Germanium Sulfide System

Abstract

In the present work, the (x)H2S + (1−x)GeS2 system has been systematically investigated to determine the incorporation of hydrogen into the tetrahedral germanium sulfide network. Reactions between gaseous H2S and glassy-GeS2 have been explored over a range of temperatures and pressures. Reactions for shorter times and lower temperatures (ambient through 250 °C) produced the protonated thiogermanic acid H4Ge4S10 with an adamantane-like microstructure. In contrast, longer reaction times produced the unprotonated lowtemperature three-dimensional α-GeS2 crystal structure. At higher temperatures (750 °C), sublimation reactions produced weakly protonated amorphous materials in the form of spherical particles (100 nm to a few μm). Structural characterizations of the obtained amorphous and crystalline materials have been performed using IR and Raman spectroscopies, thermogravimetric analysis, ac impedance spectroscopy, and SEM. Thermal mass loss measurements and quantitative IR of the S−H stretching region 2500 cm-1 were used to determine the amount of hydrogen incorporated into the GeS2 network. Disciplines

Synthesis and characterization of germanium sulfide aerogels

“…The peaks at 346 and 348 cm À1 are assigned to the Ge-S-Ge A 1 symmetric stretch mode, while that at 374 cm À1 is assigned to the so-called A c 1 companion stretch mode [31][32][33][34]. The band at 415 cm À1 is attributed to GeS À , arising from a possible cleavage of Ge-S-Ge bridges [35,36], while those at 437-440 cm À1 are assigned to the stretching mode of S-S dimers at the surface [32,34]. For the crystalline aerogels, all of these bands are also seen, but there are additional bands at 520, 774 and 881 cm À1 (Fig.…”

“…Stanić et al have also reported a range of stoichiometries for the Ge:S xerogels that vary from 1:1.2 to 1:2.6 for R = 1.32 and 10, respectively [25]. Additionally, non-stoichiometric GeS x glasses are routinely prepared by melting elemental Ge and S in varying ratios [34,35]. Unlike SiO 2 -gels and aerogels, the GeS x materials produced here could not be prepared as monoliths (even at higher concentration of H 2 S, R = 3.6), but instead formed as a fluffy white powder.…”

Tuning the Morphology of GeS2 Hybrid Materials Using Ionic Liquids as Structuring Agents

“…Decomposition of the inorganic part is highly improbable. As a matter of fact, TG analysis of amorphous GeS 2 reported by Sutherland et al18 shows that the compound is stable at least up to 500 °C. The weight loss is therefore attributed to the particle decomposition and loss of its organic moiety.…”

Crystal Growth Kinetics in GeS2 Glass and Viscosity of Supercooled Liquid

“…The relatively low value of Poisson’s ratio (υ = 0.28) for GeS 2 glass indicates an intermediate between the highly cross-linked 3D network and the weakly correlated 2D network. , This is likely also the reason why it is so difficult to prepare pure crystalline β-GeS 2 by crystallization of a glass precursor by a thermal treatment. It seems that the final product is always contaminated by the α-GeS 2 phase, even when the treatment takes place well below the β → α transition range, except the glassy precursor, which has been carefully purified by distillation. , Therefore, for synthesis of high purity β-GeS 2 , the high-pressure hydrothermal synthesis described by Wang and Horn or the hydrogen sulfide synthesis described by Sutherland et al , should be considered.…”

“…It seems that the final product is always contaminated by the α-GeS 2 phase, even when the treatment takes place well below the β → α transition range, except the glassy precursor, which has been carefully purified by distillation. 21,37 Therefore, for synthesis of high purity β-GeS 2 , the high-pressure hydrothermal synthesis described by Wang and Horn 5 or the hydrogen sulfide synthesis described by Sutherland et al 43,44 should be considered. Significantly higher crystal growth velocity of β-GeS 2 in the amorphous thin film vs bulk surface connected with weaker viscous flow dependence clearly indicates that the molecular crystal growth rate and viscosity are probably decoupled; this is discussed further, below.…”