Irradiation- vs. vitrification-induced disordering: The case of 𝜶-quartz and glassy silica

Abstract

Irradiation and vitrification can both result in the disordering of minerals. However, it remains unclear whether these effects are comparable or if the glassy state represents an upper limit for irradiation-induced disordering. By reactive molecular dynamics simulations, we compare the structure of irradiated quartz to that of glassy silica. We show that although they share some degree of similarity, the structure of irradiated quartz and glassy silica differs from each other, both at the short- (<3 Å) and the medium-range (>3 Å and <10 Å). In particular, the atomic network of irradiated quartz is found to comprise coordination defects, edge-sharing units, and large rings, which are absent from glassy silica. These results highlight the different nature of irradiation- and vitrification-induced disordering.

Rate controls on silicate dissolution in cementitious environments

“…In a different albeit related context, at a constant composition, external stimuli ("shock") in the form of temperature and pressure impositions, and irradiation can alter the network topology of a solid, e.g., from the crystalline to increasingly disordered states [26,32,49]. This nature of alterations which may occur, e.g., when minerals are exposed to radiation in the form of neutrons in nuclear power plants, can alter the chemical durability of the mineral(s), and in turn, the surrounding concrete due to the potential onset of ASR in even otherwise unreactive aggregates [32,[66][67][68][69][70].…”

“…3a) elevates by up to 20x following irradiation, the dissolution rate of quartz elevates by up to 500x following irradiation, broadly for pH levels greater than 10 (pH units). Herein, it should be noted that although the atomic structure of terminally irradiated minerals differs from that of its compositionally equivalent glass (e.g., see [49]), radiation exposure does indeed result in the irradiated mineral and its equivalent glass featuring similar dissolution rates (e.g., see Fig. 3b for dissolution rates of glassy silica and irradiated quartz).…”

“…MD simulations of irradiation-induced structural alterations in albite and α-quartz were carried out following the methodology of Wang et al [24,49]; e.g., see Fig. 1(b) for irradiation induced disordering of α-quartz.…”

“…This enables the system to equilibrate its density following irradiation. This process is repeated iteratively with different knock-on atoms, until the system exhibits saturation in terms of its enthalpy and density [49]. A Buckingham potential parameterized by Teter and splined with the Ziegler-Biersack-Littmark (ZBL) potential was used to ensure realistic short-range repulsive interactions during the ballistic cascades [52].…”

Rock-Forming Minerals Radiation-Induced Volumetric Expansion – Revisiting Literature Data

“…(α-SiO 2 ) is a simple binary oxide and predominantly a covalent-bond material. As such, its simple structure, unique within the silicates family, has led to an abundant literature on the effects of varied irradiation, e.g., (Frondel 1945;Wittels and Sherrill 1954;Primak 1958;Mayer and Lecomte 1960;Weissmann and Nakajima 1963;Grasse et al 1981;de Goer 1986;Inui et al 1990;Bonnet et al 1994;Harbsmeier and Boise 1998;Lebedev et al 2007;Ibragimova et al 2014;Krishnan et al 2017a). "The displacement of atoms in quartz causes a reduction of long-range periodicity at the expense of forming rearranged and distorted polyhedra in order to maintain the short-range bonding requirements."…”