Structure from glass to melt: a case study along the MgSiO 3 –CaSiO 3 join using neutron and X-ray diffraction

Abstract

Glass and melt structures are inherently complex and disordered with significant changes expected to occur with temperature. In the present paper, a comparison of the structure of glasses and liquids along the MgSiO 3 -CaSiO 3 join is carried out using neutron and X-ray diffraction (XRD). Empirical Potential Structure Refinement (EPSR) simulations were used to fit the experimental data. The average coordination number (CN) and site distribution is obtained for Mg and Ca showing distinct sites between the two cations and higher coordinated sites in the liquids. The major glass to melt modifications is observed at the scale of intermediate range order (IRO) by rearrangement of the (Ca,Mg)-Si and (Ca,Mg)-(Ca,Mg) connections. The structural evolution with temperature, especially concerning the cationic environments, illustrates the differences between glass and melt organization. These changes highlight the important contribution of cations to thermodynamical properties, diffusion and glass forming ability.

Structural Analysis of Si-Doped Amorphous In2O3: Insights from Quantum Beam Measurements and Computer Simulations

“…In contrast, in the NIn-O without SiO4 tetrahedra, the addition of Si led to broader peaks and decreased coordination numbers. This phenomenon is similar to that observed in amorphous materials 23,26 .…”

“…In addition, the combination of quantum beam measurements and computer simulations is a well-known approach for elucidating atomic structures in greater detail. Classical molecular dynamics (CMD) and density functional theory (DFT) are commonly used for modeling inorganic materials 26,27 , offering methods for generating three-dimensional structures and understanding various features such as atomic distances, bond angles, and electronic states. Previous studies have employed simulation techniques to investigate a-In2O3 28,29 .…”

Atomic and Electronic Structure in MgO–SiO2

“…The average CN Mg–O of DF–MD model of g -MgSiO 3 shows 5.0 and the distribution of the value CN Mg–O gives [4] Mg (21.6%), [5] Mg (55.9%), and [6] Mg (22.5%) using the cutoff distance 2.60 Å. The previous results obtained by neutron diffraction, RMC, and empirical potential structure refinement (EPSR) show CN Mg–O around 4.50, 4.50, and 4.48, respectively. Our DF–MD model has higher CN Mg–O than those because a lot of [5] Mg exist.…”

The structure of CaO–MgO–Al2O3–SiO2 melts and glasses doped with FeOX–NiO

“…These densities are in good agreement with previous studies on similar systems. 8,34 Structural models for the glasses and the liquids were derived from the diffraction data using EPSR. 35,36 This method generates a box of atoms based on the atomic composition of the sample, then refines the model to agree with the data.…”

“…The exception was the parameters for Ca due to the propensity of its first coordination shell to distort, such that different starting EPSR parameters have been suggested. 8,38 Here, the Ca Lennard-Jones potential (labeled Ca1) was empirically fitted for CMAS-2 and CMAS-3 to provide the best agreement to the data. The Ca1 parameters were also used to model the CMAS-1 data, but the agreement was worse due to a combination of both long and short bonds in its first coordination shell.…”