Molecular simulations of silicate melts doped with sulphur and nitrogen

Modeling Solubility of Fe-Ni Sulfides in Basaltic Magmas: The Effect of Nickel

“…This study concluded that "reduced sulfur is associated with network modifiers and does not replace bridging oxygen in substantial amounts," and that "free S 2− is not relevant in silicate melts" (Wilke et al, 2011, p. 52 and p. 73). This is also supported by a molecular simulation study (Machacek et al, 2010). Based on a thorough spectroscopic study of hydrous glasses, Klimm et al (2012) demonstrated that both SH − and H2S are present in Fe-free silicate systems, whereas in the presence of iron both these forms are absent so that only Fe-S complexes exist in the melt.…”

A Raman calibration for the quantification of SO42−groups dissolved in silicate glasses: Application to natural melt inclusions

“…This width value has been chosen in the light of the SO4 2group dissolution mechanisms. Recent works suggest that SO4 2dissolves in the silicate melt structure either by scavenging non-bridging oxygen (Morizet et al 2013a(Morizet et al , 2015b or possibly in a similar way to CO3 2groups by forming free M n+ ..SO4 2clusters (Brooker et al 2001b;Machacek et al 2010;Morizet et al 2015b;Moussallam et al 2016) where M n+ is a charge balancing cation of different nature (e.g. Ca 2+ or Mg 2+ ).…”

The effect of sulphur on the glass transition temperature in anorthite–diopside eutectic glasses

“…In fact the formation of the Si-O-S is strong enough to change the 29 Si NMR spectral signature so as to mimic a polymerization effect of SO 2 dissolution onto the melt structure. In other words, the shift of -3 ppm in the 29 Si peak maximum witnessing the apparent increase in melt polymerization only reflects the consumption of non-bridging oxygen by SO 2 molecules to form SO 4 2molecular groups (Manara et al, 2007;Machacek et al, 2010). Consequently, the dissolution of SO 2 molecules in silicate melts does not induce the formation of Si-O-Si bonds, which should be accompanied by an increase in glass transition temperature which is related to the kinetic rate of forming/breaking of Si-O-Si bonds (Liu et al, 1988;Moynihan, 1995).…”

“…The potential slight decrease in Tg with increasing S evidenced by fit parameters of Eq. 2 is more difficult to explain as it implies that Si-O-Si molecular bonding are broken upon S dissolution which is unlikely (Machacek et al, 2010). If S dissolution does induce major changes on the silicate network structure, an alternative explanation is that the dissolution of S as SO 4 2induces slight geometrical changes (Si-O bond length and/or angle).…”