Importance of interlayer H bonding structure to the stability of layered minerals

Abstract

Layered (oxy) hydroxide minerals often possess out-of-plane hydrogen atoms that form hydrogen bonding networks which stabilize the layered structure. However, less is known about how the ordering of these bonds affects the structural stability and solubility of these minerals. Here, we report a new strategy that uses the focused electron beam to probe the effect of differences in hydrogen bonding networks on mineral solubility. In this regard, the dissolution behavior of boehmite (γ-AlOOH) and gibbsite (γ-Al(OH)3) were compared and contrasted in real time via liquid cell electron microscopy. Under identical such conditions, 2D-nanosheets of boehmite (γ-AlOOH) exfoliated from the bulk and then rapidly dissolved, whereas gibbsite was stable. Further, substitution of only 1% Fe(III) for Al(III) in the structure of boehmite inhibited delamination and dissolution. Factors such as pH, radiolytic species, and knock on damage were systematically studied and eliminated as proximal causes for boehmite dissolution. Instead, the creation of electron/hole pairs was considered to be the mechanism that drove dissolution. The widely disparate behaviors of boehmite, gibbsite, and Fe-doped boehmite are discussed in the context of differences in the OH bond strengths, hydrogen bonding networks, and the presence or absence of electron/hole recombination centers.

Visualising early-stage liquid phase organic crystal growthvialiquid cell electron microscopy

“…Delamination of complex hydrogen bonded networks such as hydroxide mineral materials has previously been observed with naturally occurring layered bohemite via LCEM. 33 Delamination of such hydrated hydroxide materials has been theorised to be caused by a number of factors including radiolysis and also disruption of the hydrogen bonding network when a hole is created in place of a hydrogen atom, thus altering the negative charge and hydrogen bonding capability of the layers. Unlike the work done by Conroy et al, 33 in our work, the layers did not experience dissolution upon delamination as the solvent and the material Fig.…”

“…33 Delamination of such hydrated hydroxide materials has been theorised to be caused by a number of factors including radiolysis and also disruption of the hydrogen bonding network when a hole is created in place of a hydrogen atom, thus altering the negative charge and hydrogen bonding capability of the layers. Unlike the work done by Conroy et al, 33 in our work, the layers did not experience dissolution upon delamination as the solvent and the material Fig. 1 Schematic illustrating the bonding characteristics, unit cell conformation, BFDH and Attachment Energy (AE) predicted morphology of form I and form III.…”

Intensive study on structure transformation of muscovite single crystal under high-doseγ-ray irradiation and mechanism speculation

“…As a result, the OH vector is not parallel to the z -direction. The formation of hydrogen bond strengthens the interlayer force within tetrahedron and octahedron sheets [74], shrinking the interlayer space. That means extra hydrogen bond formation might result in shrinking.…”

Electron irradiation induced amorphous SiO2 formation at metal oxide/Si interface at room temperature; electron beam writing on interfaces

“…On the other hand, the radiolytic processes have practically no threshold since because of the multiple interactions nearly any type of excitations can happen. E.g., recently the dissolution of boehmite under the high energy electron irradiation (TEM studies) was explained by the electron-hole pairs created during the electron bombardment 22 . This explanation is rather similar to those developed long time ago for the description of low-energy electron-stimulated desorption (ESD) 23 – 25 which can readily be applied for the explanation of our observations.…”