Ab-initio molecular dynamics simulations of the structure of liquid aluminates

Molecular Dynamics Simulations of the Structure and Properties of Low Silica Yttrium Aluminosilicate Glasses

“…With increasing silica content, the percentage of six‐coordinated yttrium ions increases and the percentages of seven‐ and eight‐coordinated yttrium ions decrease. The Y–O bond length in aluminosilicate glasses from diffraction studies ranges from 2.20 to 2.26 Å, 18 and the yttrium coordination number ranges from 6.5 to 7.3, depending on the cutoff distance 33 . The decrease of the yttrium coordination number with increasing silica content can be understood by the decrease of the total available oxygen ions in the system when yttria is substituted by silica and by the stronger ability of silicon cation (higher field strength) to attract oxygen ions.…”

“…MD simulations of alkali 28,29 and alkali earth 30,31 aluminosilicate glasses have been reported. The yttrium and lanthanum aluminate glasses have been studied using classical MD simulations to understand the polyamorphism in these systems, 32,33 and we have recently reported using MD simulations to interpret the diffraction data of lanthanum aluminate glasses, 34 but there are no reported simulations on the ternary rare earth aluminosilicate systems. In this paper, we present MD simulations of a series of low silica yttrium aluminosilicate glasses.…”

Molecular simulations of silicate melts doped with sulphur and nitrogen

“…The five-coordinated silicon atoms, SiO 5 , were found to be responsible for the formation and annihilation of S-O-Si bonds. The SiO 5 species were experimentally identified by 29 Si MAS-NMR in rapidly cooled glasses. They are the intermediates of oxygen diffusion and viscous flow [23,41].…”

“…Recently, the ab initio molecular dynamics has been used to study the structure and properties of many oxide glasses including silica [19], silicate [20][21][22][23] phosphosilicate [24], oxynitride [25,26], and aluminate glasses [27][28][29]. The chemical processes in the hydrous silica melt (3.84 wt.% H 2 O) at 3000 K and 3500 K [30] were simulated by the ab initio Car-Parrinello MD with 102 atoms, the PBE exchange-correlation functional, norm-conserving pseudopotentials, and plane-wave cut-off energy of 650 eV.…”

The coordination number calculation from total structure factor measurements

“…It is necessary to be careful when this method is used for distances beyond 3-4 Å, and in most of cases a comparison with numerical simulations is necessary [18].…”