Electronic structures and physical properties of Na2O doped silicate glass

Abstract

Ab initio molecular dynamics has been applied to construct seven sodium silicate glass models with Na2O concentration ranging from 0 to 50 mol. %. The structures of the simulated (Na2O)x(SiO2)1-x glasses are critically analyzed and validated by comparing with available experimental data. Because the initial seed model is based on a near-perfect continuous random network model for amorphous SiO2 with periodic boundaries, the structures of these silicate glasses are highly reliable. The electronic structure, interatomic bonding, and the mechanical and optical properties of seven models are calculated using the first-principles density functional method. In particular, a single quantum mechanical metric, the total bond order density (TBOD), is used to characterize the internal cohesion of sodium silicate glass. This is a significant step beyond the traditional analysis of glasses based purely on the geometric parameters. The TBOD value is found to decrease with increasing Na content, indicating the destruction of silica network connectivity. The calculated mass density and refractive index increase with x are in good agreement with experiment. The elastic coefficients and bulk mechanical properties exhibit a nonlinear variation in the series and depend greatly on the internal bonding and cohesion of the glass. The calculated Poisson's ratio indicates that the glass becomes more ductile with the addition of Na2O. Our results indicate that sodium silicate glass tends to be unstable for x greater than 0.4 due to the total destruction of the SiO2 network.

First‐principles study in an inter‐granular glassy film model of silicon nitride

“…The method and approach we suggested and successfully implemented can be applied to systems that are not restricted to traditional structural ceramics. For example, it can be used to explore the role of alkali doing or mixed doping in silicate glasses, strengthening of Ni‐based super alloys, Inconel740 and Haynes282 by strategic inclusion of precipitate phases, or even organic or biological elements such as peptides in conjunction with crystalline calcium carbonate crystals as part of nature inspired materials, insertion of crystallites of metallic alloys in bulk metallic glasses etc. The opportunities are unlimited.…”

“…The OLCAO method uses atomic orbitals for the basis function expansion and is particularly effective for the electronic structure of large complex systems. The combination of VASP for structural optimization and OLCAO for properties evaluation has been successfully demonstrate in many crystalline and noncrystalline materials, and also in complex biomolecular systems . In the present calculation, the basis consists of 1s, 2s, 2p, 3p, and 3d orbitals for Si and 1s, 2s, 2p orbitals for N and O.…”

Complex interplay of interatomic bonding in a multi-component pyrophosphate crystal: K2Mg (H2P2O7)2·2H2O

“…This approach for mechanical properties has been successfully used by us in many different inorganic crystals and glasses [44,53–57]. …”

Predicting properties of MgO·nAl2O3 by first‐principles calculation combined with bond valence models

“…[16][17][18][19][20][21][22] However, it is troublesome to describe the structures of disordered solid solutions by first-principles calculation. [16][17][18][19][20][21][22] However, it is troublesome to describe the structures of disordered solid solutions by first-principles calculation.…”

“…It is well-known that first-principles calculation has been widely applied to predict structures and properties of materials owing to its reasonable accuracy and high-computational efficiency. [16][17][18][19][20][21][22] However, it is troublesome to describe the structures of disordered solid solutions by first-principles calculation. So far, some techniques, such as special quasirandom structure (SQS) [23][24][25] and virtual crystal approximation (VCA) 26 , etc.…”