Interlayer bonding energy of layered minerals: Implication for the relationship with friction coefficient

Abstract

The frictional strength of layered minerals is an important component of fault slip physics. A low‐friction coefficient of these minerals has been attributed to the interlayer bonding energy (ILBE) of their weak interlayer bonding. The ILBE used for discussing the friction coefficient is based on a simple electrostatic calculation; however, the values should be revisited by precise calculations based on quantum mechanics. In this study, the ILBEs of layered minerals were calculated by using the density functional theory (DFT) method with van der Waals correction. The ILBEs calculated by the simple electrostatic method for hydrogen‐bonding minerals such as kaolinite, lizardite, gibbsite, and brucite strongly overestimated the reliable energies calculated by the DFT method. This result should be ascribed to the inaccurate approximation of the point charges at the basal plane. A linear relationship between the experimentally measured friction coefficients of layered minerals and the ILBEs determined by the simple method was not confirmed by using the reliable ILBEs calculated by our DFT method. The results, however, do not remove the possibility of a relationship between interlayer bonding energy and the friction coefficient because the latter, used for comparing the former, was obtained through experiments conducted under various conditions.

Frictional strength of wet and dry montmorillonite

“…Morrow et al . [], Moore and Lockner [], and Behnsen and Faulkner [] found that the dry frictional strength of the 2:1 sheet silicate minerals is correlated with the strength of their calculated interlayer, (001), bonds [ Giese ; Sakuma and Suehara ]. The (001) bond strength is a function of the layer charge and whether or not the mineral is dioctahedral or trioctahedral [ Giese ].…”

“…Frictional strength of montmorillonite and its dependence on normal stress are strongly dependent on whether the sample is dry or wet and, if wet, are functions of saturation state. Morrow et al [2000], , and Behnsen and Faulkner [2012] found that the dry frictional strength of the 2:1 sheet silicate minerals is correlated with the strength of their calculated interlayer, (001), bonds [Giese 1978;Sakuma and Suehara 2015]. The (001) bond strength is a function of the layer charge and whether or not the mineral is dioctahedral or trioctahedral [Giese 1978].…”

Effects of humidity and interlayer cations on the frictional strength of montmorillonite

“…Moore and Lockner (2004) suggested that the (001) bonding strength is a primary factor controlling frictional coefficient of the sheet silicates; however, recent experiments by Behnsen and Faulkner (2012) found the friction coefficient of various clay minerals were deviated significantly from the value predicted from the electrostatic separation energy. Sakuma and Suehara (2015) calculated interlayer bonding energy using the first-principles based density functional theory without using the empirical approximation of charge distributions in minerals, and they showed that there is no clear correlation with the frictional strength for layered minerals. Experiments using a single crystal of muscovite showed a markedly lower shear resistance than those using powder sample, suggested that the sliding does not necessarily occur only on the basal plane in the clay-bearing gouges (Kawai et al 2015).…”

Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

“…Especially, surfaces and interlayers of phyllosilicate were studied by DFT calculations [13][14][15]. The quantum chemical calculations can identify the most steady state by comparing the total energies of different structures, and analyzing the interaction between V and oxygen in the lattice, which further affects the related physical and chemical properties of muscovite.…”