Dielectric properties of smectite clays

Kaviratna, Padmananda D.; Pinnavaia, Thomas J.; Schroeder, P. A.

doi:10.1016/s0022-3697(96)00076-5

Cited by 110 publications

(92 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Diffraction patterns along the (OOL) direction show that three stable hydration states are found in Na-fluorohectorite, as has been reported previously [4]. From the dehydrated ,tatewith basal spacing c = 9,7~( Fig.1, dashed line), the lattice spacing swells to 12.4w hen the temperature is reduced to the range 30-60"C, depending on how much water vapor is available (Fig.…”

Section: Resultssupporting

confidence: 76%

Synchrotron x-ray study of hydration dynamics in the synthetic swelling clay Na-fluorohectorite

DiMasi¹,

Fossum²,

Dasilva³

2003

2001. A Clay Odyssey

View full text Add to dashboard Cite

We present time-resolved synchrotronsx-ray diffraction from the swelling clay Na fluorohectc)rite during controlled hydration and dehydration. A comparison of bulk and surface scattering reveals that the time dependence of basal Bragg peak positions and intensities has two components, which come into play at distinct temperatures. Intercalation of water into the crystal structure commences at a temperature of about 60"C, on a time scale on the order of 1 hour. By contrast, percolation of water into the porous medium has a characteristic time constant of 3-4 h. This is the rate limiting process for hydration of the interior of the clay for T > 40°C. We suggest that the temperature-dependent percolation step may account for some of the hysteresis reported in earlier diffraction studies of the hydri~tion of similar systems.

show abstract

Section: Resultssupporting

confidence: 76%

Synchrotron x-ray study of hydration dynamics in the synthetic swelling clay Na-fluorohectorite

DiMasi¹,

Fossum²,

Dasilva³

2003

2001. A Clay Odyssey

View full text Add to dashboard Cite

show abstract

“…Fluorohectorite has a rather large surface charge of 1.2 e-/unit cell, as compared to synthetic smectites such as laponite (0.4 e-/unit cell) [20]; this high surface charge explains why clay stacks stay intact when suspended in water, unlike laponite or the natural clay montmorillonite. The natural smectite illite, on the other hand, behaves much like fluorohectorite in this respect [21].…”

mentioning

confidence: 99%

Intercalation-enhanced electric polarization and chain formation of nano-layered particles

et al. 2006

View full text Add to dashboard Cite

ray scattering (including small-angle scattering). PACS. 82.70.Dd -Colloids. PACS. 83.80.Gv -Electro-and magnetorheological fluids.Abstract. -Microscopy observations show that suspensions of synthetic and natural nanolayered smectite clay particles submitted to a strong external electric field undergo a fast and extended structuring. This structuring results from the interaction between induced electric dipoles, and is only possible for particles with suitable polarization properties. Smectite clay colloids are observed to be particularly suitable, in contrast to similar suspensions of a nonswelling clay. Synchrotron X-ray scattering experiments provide the orientation distributions for the particles. These distributions are understood in terms of competing (i) homogenizing entropy and (ii) interaction between the particles and the local electric field; they show that clay particles polarize along their silica sheet. Furthermore, a change in the platelet separation inside nano-layered particles occurs under application of the electric field, indicating that intercalated ions and water molecules play a role in their electric polarization. The resulting induced dipole is structurally attached to the particle, and this causes particles to reorient and interact, resulting in the observed macroscopic structuring. The macroscopic properties of these electrorheological smectite suspensions may be tuned by controlling the nature and quantity of the intercalated species, at the nanoscale.In this letter we study colloidal suspensions of electrically-polarizable particles in nonconducting fluids. When such suspensions are subjected to an external electric field, usually of the order of 1kV/mm, the particles become polarized, and subsequent dipolar interactions are responsible for aggregating a series of interlinked particles that form chains and columns parallel to the applied field. This structuring occurs within seconds, and disappears almost instantly when the field is removed [1][2][3][4][5]. It coincides with a drastic change in rheological properties (viscosity, yield stress, shear modulus, etc.) of the suspensions [6], which is why they are sometimes called electrorheological fluids (ERFs). This makes the mechanical behavior readily controllable by using an external electric field [1][2][3][4][5][6][7]. Particle size has a quite diverse impact on the behavior of ERFs [8]. The nature of the insulating fluid and of the colloidal particles determines the electrorheological behavior of the suspensions. The mechanism is not fully understood yet, but it is mainly triggered by the so-called interfacial polarization, EDP Sciences

show abstract

“…In Na-FH clay there is, order of magnitude, 1 unit electron charge per nm 3 of material [17]. Here, the typical plate aggregates have a volume of order of magnitude 10 6 × 10 7 × 10 7 nm 3 = 10 20 nm 3 , giving a total order of magnitude 10 C charge associated with physically bound charge compensating ions in our plate aggregate.…”

Section: Plate Ratiomentioning

confidence: 86%

Electric Alignment of Plate Shaped Clay Aggregates in Oils

et al. 2016

View full text Add to dashboard Cite

We experimentally investigate the rotation of plate shaped aggregates of clay mineral particles immersed in silicone oil. The rotation is induced by an external electric field. The rotation time is measured as a function of the following parameters: electric field strength, the plate geometry (length and width) and the dielectric properties of the plates. We find that the plates always align with their longest axis parallel to the direction of the electric field (E), independently of the arrangement of individual clay mineral particles within the plate. The rotation time is found to scale as E −2 and is proportional to the viscosity (η), which coincides well with a model that describes orientation of dipoles in electric fields. As the length of the plate is increased we quantify a difference between the longitudinal and transverse polarizability. Finally, we show that moist plates align faster. We attribute this to the change of the dielectric properties of the plate due to the presence of water.

show abstract

Dielectric properties of smectite clays

Cited by 110 publications

References 29 publications

Synchrotron x-ray study of hydration dynamics in the synthetic swelling clay Na-fluorohectorite

Synchrotron x-ray study of hydration dynamics in the synthetic swelling clay Na-fluorohectorite

Intercalation-enhanced electric polarization and chain formation of nano-layered particles

Electric Alignment of Plate Shaped Clay Aggregates in Oils

Contact Info

Product

Resources

About