Texture

Graphite powders typically consist of polycrystalline particles having the shape of platelets, which are agglomerates of intergrown single crystals. The graphite texture describes the orientation of the single crystal in the particle (mosaicity). Two extreme cases of graphite textures are schematically illustrated in Fig. 4. The first case contains few, relatively large, single crystals, which are aligned along the platelet plane and give rise to relatively strong anisotropic material properties. Such types of textures typically can be found in graphites with flaky or anisometric particle shapes. The second case contains many relatively small single crystals that are randomly oriented in the particle, giving rise to more isotropic properties. Such types of textures typically can be found in graphite materials with isometric particle shapes.

The specific (BET) surface area, which is measured by nitrogen adsorption (ISO 9277:2010), consists of surface area fractions contributed by the geometrical surface area, by the surface roughness and surface defects, as well as by the mesopores. Most of the internal porosity in the graphite particle is created by the interspaces between the crystalline domains. Smaller crystalline domains usually result in a higher porosity. The geometric surface area is related to the particle dimensions. It increases with decreasing particle size distribution. For fine graphite powders, the increase of the geometric surface area is the main reason for the increase of the specific BET surface area.

 
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