Advancing the Mechanical Performance of Glasses: Perspectives and Challenges

Abstract

in terms of deciphering structure-property relationships and the nonaffine nature of glass mechanical behavior, of computational and computer-assisted methods for accelerated materials discovery, and of physicochemical insight at glass formation and synthesis in unconventional types of materials. Despite this progress, significant questions remain as to the fundamental role of structural heterogeneity and its consequences for the predictability of mechanical properties underlying the many applications of glass. Today's challenge is to translate new understanding of the physics of disorder, glass chemistry, and surface mechanics into tools that enable future glass products with adapted elasticity, strength, and toughness. We will therefore consider fundamental advances in relation to emerging glass applications. While the aforementioned physical insights have mostly been obtained by computational simulation of model systems, and often through the examination of metallic glasses, we will here focus on glasses suitable for visible transparency, in particular silicate glasses, such as a representative of today's most prolific glass devices, ranging from ultrathin substrates to strong and visually transparent cover materials. We will further consider hybrid glasses and glass-like composite materials as emerging alternatives that may overcome the ubiquitous conflict between strength and toughness. [1] Glasses are materials that lack a crystalline microstructure and long-range atomic order. Instead, they feature heterogeneity and disorder on superstructural scales, which have profound consequences for their elastic response, material strength, fracture toughness, and the characteristics of dynamic fracture. These structure-property relations present a rich field of study in fundamental glass physics and are also becoming increasingly important in the design of modern materials with improved mechanical performance. A first step in this direction involves glass-like materials that retain optical transparency and the haptics of classical glass products, while overcoming the limitations of brittleness. Among these, novel types of oxide glasses, hybrid glasses, phase-separated glasses, and bioinspired glass-polymer composites hold significant promise. Such materials are designed from the bottom-up, building on structure-property relations, modeling of stresses and strains at relevant length scales, and machine learning predictions. Their fabrication requires a more scientifically driven approach to materials design and processing, building on the physics of structural disorder and its consequences for structural rearrangements, defect initiation, and dynamic fracture in response to mechanical load. In this article, a perspective is provided on this highly interdisciplinary field of research in terms of its most recent challenges and opportunities.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202109029.

Vibrational disorder and densification-induced homogenization of local elasticity in silicate glasses

“…Elasticity is a primary design target in modern glass science and technology 1 , 2 . For a variety of applications, it is often desirable to adapt glass formulations for enhanced shear and/or Young’s modulus and, thus, enhanced rigidity or stiffness 3 .…”

Multifunctional metasails for self-stabilized beam-riding and optical communication

“…Although with the current technology one can enable centimeter-scale metasurfaces, larger dimensions could be achieved by assembling and sticking together small scale blocks, which requires advances in thin-lm technology. 16,[64][65][66][67][68] The Starshot program is a long-term project and research on the different aspects of it is currently in progress.…”

Fracture energy of high-Poisson's ratio oxide glasses

“…We note that the use of the load cell of 1 kN or smaller for the three-point bending step is important here, for the reason of precision, since the precracked specimens break mostly when the applied load is below 10 N. The fractured specimen, after the three-point bending test, was then used to measure the fracture surface (as illustrated in Figure 1d and described in detail in Ref. [2]). From the three-point bending test, we also measured the load-displacement curves to obtain the work of fracture (wof, see Section 2.4), and together with the fracture surface (A as in Figure 1e), we calculated the fracture energy (Figure 1e-g).…”

“…However, the brittleness of oxide glasses is the major hindrance for their possible use in various functional applications [1,2]. The theoretical strength of oxide glasses is estimated to be around a hundred times higher than their practical strength.…”