Evidence of Multiple Crystallization Pathways in Lithium Disilicate: A Metadynamics Investigation.

Metadynamics simulations driven by using two X-ray diffraction peaks identified three alternative crystallization pathways of the lithium disilicate crystal from the melt. The most favorable one passes through the formation of disordered layered structures undergoing internal ordering in a second step. The second pathway involves the formation of phase-separated structures composed of nuclei of β-cristobalite crystals surrounded by lithium-rich phases in which metasilicate chains are formed.

Biasing crystallization in fused silica: An assessment of optimal metadynamics parameters.

Metadynamics (MetaD) is a useful technique to study rare events such as crystallization. It has been only recently applied to study nucleation and crystallization in glass-forming liquids such as silicates, but the optimal set of parameters to drive crystallization and obtain converged free energy surfaces is still unexplored. In this work, we systematically investigated the effects of the simulation conditions to efficiently study the thermodynamics and mechanism of crystallization in highly viscous systems.

Disclosing crystal nucleation mechanism in lithium disilicate glass through molecular dynamics simulations and free-energy calculations.

Unraveling detailed mechanism of crystal nucleation from amorphous materials is challenging for both experimental and theoretical approaches. In this study, we have examined two methods to understand the initial stage of crystal precipitation from lithium disilicate glasses using molecular dynamics simulations. One of the methods is a modified exploring method to find structurally similar crystalline clusters in the glass models, enabling us to find three different embryos, such as LiSiO (LS), LiSiO (LS) and LiPO (LP), in the 33LiO·66SiO·1PO glass (LSP1), in which PO is added as a nucleating agent.

Structural origins of the Mixed Alkali Effect in Alkali Aluminosilicate Glasses: Molecular Dynamics Study and its Assessment.

The comprehension of the nonlinear effects provided by mixed alkali effect (MAE) in oxide glasses is useful to optimize glass compositions to achieve specific properties that depend on the mobility of ions, such as the chemical durability, glass transition temperature, viscosity and ionic conductivity. Although molecular dynamics (MD) simulations have already been applied to investigate the MAE on silicates, less effort has been devoted to study such phenomenon in mixed alkali aluminosilicate glasses where alkali cations can act both as modifiers, forming non-bridging oxygens and percolation channels, and as charge compensator of the AlO units present in the network. Moreover, the ionic conductivity has not been computed yet; thus, the accuracy of the atomistic simulations in reproducing the MAE on the property is still open to question.