See cell parameters.

See zeolite.

For phyllosilicates, a layer (see Fig. 1) contains one or more tetrahedral sheets and an octahedral sheet. There are two types of layers, depending on the ratios of the component sheets: a “1:1 layer” has one tetrahedral sheet and one octahedral sheet, whereas a “2:1 layer” has an octahedral sheet between two opposing tetrahedral sheets. Quot Guggenheim et al. (2006).
See references therein.
Cf., plane, sheet, tetrahedral sheet, octahedral sheet

In phyllosilicates, the “layer charge”, “net layer charge”, or “permanent layer charge” is the total negative charge deviation from an ideal, unsubstituted dioctahedral or trioctahedral composition. In addition, phyllosilicates may have other charge effects on their surface, commonly referred to as the “variable layer charge”. For example, for an R³⁺-rich dioctahedral 2:1 layer, the layer composition is ideally: R₂Si₄O₁₀(OH)₂. In muscovite mica where R = Al and there is an Al substituted Si site, the layer composition is: Al₂(Si₃Al)O₁₀(OH)₂ and because an Al³⁺ substitutes for an Si⁴⁺, there is an unsatisfied residual charge on the layer that results, a layer charge of -1. In muscovite, this residual charge is compensated by an interlayer cation, K⁺, so that the structure is charge neutral. Because of the anion framework of O₁₀(OH)₂, layer charges are always negative, but may be reported in the literature as either a positive or a negative value. A negative layer charge results from either a solid solution where a cation of lesser positive charge substitutes for a cation of greater charge or by a vacancy (no charge) substitution for a cation. Anion substitutions [e.g., O for (OH)] are also possible but uncommon. The location and size of the substitution has a profound effect on the physical properties of clays. The layer charge is used in the classification scheme for phyllosilicates. The variable layer charge depends on the pH of the suspension. Assuming a simple pK model, low pH values lead to protonation of the surface species OH⁰ group located at the edges or the surface and hence, to a positive variable layer charge of OH₂⁺. Increasing pH values may lead to deprotonation and hence, to a negative variable charge of O^–. The pH point where the net charge of the entire particle is zero (e.g., for a clay mineral, the positive variable change is equal to the negative permanent charge) is called “point of zero charge” (pzc).
See point of zero charge.

The sum of the intralayer displacement plus the interlayer displacement, which defines the total relative displacement between adjacent layers, as shown in Figure 1. For 2:1 layers, the layer displacement is measured from the geometric center of the ditrigonal ring. The “intralayer displacement” is the shift that originates from the octahedral slant within one layer and is measured from the geometric center of the ditrigonal ring from the lower to the upper tetrahedral sheet of that layer (Figure 1). Layer displacement should be used instead of “interlayer shift”.
Cf., interlayer, layer

See double metal hydroxides.

Composites produced on nearly any substrate, including textiles, where the composite is fabricated by successive dipping/rinsing/drying of the substrate in two different solutions, one solution containing a clay, usually montmorillonite, and the second solution containing a complimentary polymer (e.g., any polycationic polymer). These composites are typically transparent, and generally 40 to 50 bilayers thick. Layer-by-layer composites lower flammability substantially and improve gas barrier properties.
See flame retardancy

See double metal hydroxides.

See fat clay.

A poorly defined material, possibly interstratified biotite and vermiculite.