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In material science, layered materials are solids with highly anisotropic bonding, in which two-dimensional sheets are internally strongly bonded, but only weakly bonded to adjacent layers. Owing to their distinctive structures, layered materials are often suitable for
In material science, layered materials are solids with highly anisotropic bonding, in which two-dimensional sheets are internally strongly bonded, but only weakly bonded to adjacent layers. Owing to their distinctive structures, layered materials are often suitable for intercalation reaction
In chemistry, intercalation is the reversible inclusion or insertion of a molecule (or ion) into layered materials with layered structures. Examples are found in graphite and transition metal dichalcogenides.
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Examples Graphite
One famous inte ...
s.
One large family of layered materials are metal dichalcogenides. In such materials, the M-chalcogen bonding is strong and covalent. These materials exhibit anisotropic electronic properties such as thermal and electrical conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...
.
Exfoliation
Because the layers bond to each other by relatively weakvan der Waals force
In molecular physics, the van der Waals force is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and th ...
s, some layered materials are amenable to exfoliation, the complete separation of the layers of the material. Exfoliation can be done using sonication, mechanical, hydrothermal, electrochemical, laser-assisted, and microwave-assisted methods.
Typically aggressive conditions are required involving highly polar solvents and reagents. In the ideal case, exfoliation affords single-layer materials
In materials science, the term single-layer materials or 2D materials refers to crystalline solids consisting of a single layer of atoms. These materials are promising for some applications but remain the focus of research. Single-layer materials ...
, such as graphene
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure.
.
Examples
*metal dichalcogenide : 220px, Cadmium sulfide, a prototypical metal chalcogenide, is used as a yellow pigment.
A chalcogenide is a chemical compound consisting of at least one chalcogen anion and at least one more electropositive element. Although all group 16 elements ...
s such as tantalum disulfide
Tantalum(IV) sulfide is an inorganic compound with the formula Ta S2. It is a layered compound with three-coordinate sulfide centres and trigonal prismatic or octahedral metal centres. It is structurally similar to molybdenum disulfide MoS2, and ...
, titanium disulfide
Titanium disulfide is an inorganic compound with the formula Ti S2. A golden yellow solid with high electrical conductivity, it belongs to a group of compounds called transition metal dichalcogenides, which consist of the stoichiometry M E2. ...
, and vanadium disulfide.
*graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
*iron oxychloride
Iron oxychloride is the inorganic compound with the formula FeOCl. This purple solid adopts a layered structure, akin to that of cadmium chloride. The material slowly hydrolyses in moist air. The solid intercalates electron donors such as t ...
*layered double hydroxides
Layered double hydroxides (LDH) are a class of ionic solids characterized by a layered structure with the generic layer sequence cB Z AcBsub>''n'', where c represents layers of metal cations, A and B are layers of hydroxide () anions, and Z are l ...
, ionic solid
In chemistry, an ionic compound is a chemical compound composed of ions held together by Coulomb's law, electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negativ ...
s where intercalated anions are exchangeable.Khan, Aamir I.; O'Hare, Dermot "Intercalation chemistry of layered double hydroxides: recent developments and applications" Journal of Materials Chemistry (2002), 12(11), 3191-3198. {{doi, 10.1039/b204076j
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