Structure and properties of densified silica glass: characterizing the order within disorder

Abstract

The broken symmetry in the atomic-scale ordering of glassy versus crystalline solids leads to a daunting challenge to provide suitable metrics for describing the order within disorder, especially on length scales beyond the nearest neighbor that are characterized by rich structural complexity. Here, we address this challenge for silica, a canonical network-forming glass, by using hot versus cold compression to (i) systematically increase the structural ordering after densification and (ii) prepare two glasses with the same high-density but contrasting structures. The structure was measured by high-energy X-ray and neutron diffraction, and atomistic models were generated that reproduce the experimental results. The vibrational and thermodynamic properties of the glasses were probed by using inelastic neutron scattering and calorimetry, respectively. Traditional measures of amorphous structures show relatively subtle changes upon compacting the glass. The method of persistent homology identifies, however, distinct features in the network topology that change as the initially open structure of the glass is collapsed. The results for the same high-density glasses show that the nature of structural disorder does impact the heat capacity and boson peak in the low-frequency dynamical spectra. Densification is discussed in terms of the loss of locally favored tetrahedral structures comprising oxygen-decorated SiSi4 tetrahedra.

Structure of disordered materials under ambient to extreme conditions revealed by synchrotron x-ray diffraction techniques at SPring-8—recent instrumentation and synergic collaboration with modelling and topological analyses

“…In this section, we review recent structural studies on the structure of glassy, liquid and amorphous materials by diffraction techniques combined with computer simulations aided by topological analyses [4]. Over the last 20 years, we have been working on the structure of disordered materials, oxide glasses [48,53,[56][57][58][59], amorphous oxide materials [60][61][62], chalcogenide fast phase-change materials [63][64][65][66], metallic glasses [67], water [68], high-temperature oxide melt [69][70][71], densified glass [72], and other functional materials [73,74].…”

“…It is known that the FSDP of silica glass is related to the formation of a random network, as suggested by Zachariasen [75], and the model was extended to silicate glasses, as illustrated in figure 7 of reference [86], by Mei et al It was confirmed that intermediate-range ordering (IRO) arises from the periodicity of boundaries between successive small cages in the network, formed by connected regular SiO 4 tetrahedra with shared oxygen atoms at the corners. The IRO is thus associated with the formation of a ring structure and cavities [48,72]. The second maximum, the PP, reflects the size of the local-network-forming motif, whereas the FSDP indicates the arrangement of these motifs on an intermediate range, according to Zeidler and Salmon [87].…”

Coupling Raman, Brillouin and Nd3+ Photo Luminescence Spectroscopy to Distinguish the Effect of Uniaxial Stress from Cooling Rate on Soda–Lime Silicate Glass

“…This could indicate σ Nd depends on the state of disorder within the network structure. Both, a higher cooling rate as well as higher uniaxial stress, should increase the disorder state of the glass network [58,59]. Data using the σ Nd -parameter as a sensor for cooling rate or uniaxial stress in the elastic regime has not been previously reported.…”

Relationship between diffraction peak, network topology, and amorphous-forming ability in silicon and silica

“…The absence of translational periodicity and symmetry, and the rich structural complexity make it difficult to understand the order within disorder 1 , 2 in disordered materials. The advent of advanced instrumentation and measurement protocols makes it feasible to use quantum beam diffraction (X-ray diffraction (XRD) and neutron diffraction (ND)) techniques to reveal the structure of disordered materials at synchrotron and/or neutron sources 3 – 6 .…”