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Understanding the atomistic origin of hydration effects in single and mixed bulk alkali‐silicate glasses
Author(s) -
Baral Khagendra,
Li Aize,
Ching WaiYim
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15917
Subject(s) - alkali metal , silicate , materials science , silicate glass , chemical physics , aluminosilicate , mineralogy , chemistry , composite material , organic chemistry , catalysis
Abstract Silica‐water interaction plays an essential role for the mechanical strength and chemical durability of alkali‐doped‐silicate glasses. A comprehensive study of single and mixed alkali‐silicate glasses with 30% molar content of Li 2 O, Na 2 O, and K 2 O, and half‐half mixture of Li 2 O–Na 2 O, Li 2 O–K 2 O, and Na 2 O–K 2 O in hydrated models is carried out using density functional theory methods. Information on atomic geometry, electronic structure, interatomic bonding, partial charge distribution, mechanical, and optical properties are obtained and compared. It confirms that water in the solvated and confined bulk models can be either dissociated or remains as H 2 O molecule depending on the distribution and specific alkali elements. A quantum mechanical metric, the total bond order density is used to unravel the atomistic origin of the internal cohesion and strength of glasses in different environments. In particular, we show that the mechanical strength of bulk alkali‐silicate glasses is enhanced by hydration with some evidence that mixing of alkali ions tends to degrade the strength of the hydrated glasses. These results are discussed in the context of experimental observations and a few existing simulations using classical molecular dynamics.