Tailoring structure and properties of silica glass aided by computer simulation
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By using a combination of experiments and molecular dynamics simulations, our studies show that the elastic response of silica glass to initial compression gradually changes from abnormal to normal with increasing quench pressure, helium content or alkali modifier added in the glass matrix. We uncovered the structural origin of the elastic anomaly in silica glass as localized structural transitions between motifs of different stiffness that are similar to those found in its crystalline counterparts. Pressure-quenching, helium-stuffing, or alkali-modifying plays a different role in changing the structure of silica glass, but all of the resulting structures reduce the propensity for such local structural transitions to take place, thus the degree of elastic anomaly. Our studies demonstrate that by processing in ways that gradually eliminates the elastic anomaly, the degree of silica glass to undergo irreversible densification can be eventually eradicated. This provides a solid foundation for the bottom-up design of new glasses with tunable structure and properties. Dr. Liping Huang is an Associate Professor of Materials Science and Engineering at Rensselaer Polytechnic Institute in Troy, New York, USA. She obtained her Ph.D. degree from the University of Illinois at Urbana–Champaign. After several years of postdoctoral research experience at the University of Michigan and North Carolina State University, she joined RPI in 2008. Her primary research interest is to investigate the structure–property relationships at the atomic level in amorphous materials by using a combination of in-situ light scattering techniques and multiscale computer simulation methods. Among other awards, she was honored with the Norbert J. Kreidl Award from the Glass and Optical Materials Division in the American Ceramic Society in 2003. She was a recipient of the Young Investigator Award from the Defense Treat Reduction Agency in 2009, and the NSF CAREER award from the Ceramics Program in 2013. She was recently selected as one of the two inaugural Gordon S. Fulcher Distinguished Scholars to conduct her sabbatical research at Corning Incorporated in Fall 2015.
Liping Huang
I. INTRODUCTION
Characterizing the disordered structure of glass at the atomic level remains a grand challenge. On the macroscopic level, glass is structurally homogenous and isotropic; only two independent elastic constants are needed to characterize its elasticity. Elastic constants are simple to define and easy to measure/calculate, and are directly related to the interatomic forces and potentials, embodying the local structure and bonding information.1,2 Therefore, perturbing the glass with thermal or mechanical agitation (e.g., temperature, pressure, or strain) and measuring the changes in elastic moduli can be used as a probe to gain insights into the atomic level structure of glass.
Contributing Editor: Himanshu Jain a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.397
Elastic moduli and their dependence on temperature, press
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