Interfacial angle

Representation of vertical crystal faces of a hexagonal by a system of radiating normals from a point inside it. The broken lines indicate extensions of the planar faces. 

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Interfacial angle method, shape analysis of oc-tacyano complexes, 40 245-247 Interhalogens compounds... 

It will be evident that, since the faces are parallel to definite planes of lattice points, the interfacial angles are constant in different crystals of the same substance. Variations in local conditions during growth may cause some crystals of hexamethylbenzene, for instance, to be longer or thinner than others in the same batch and the eight faces of... 

Measurement of interfacial angles, and graphical representation. The most accurate method of measuring the angles between crystal faces is an optical one, which makes use of the reflection of light by the plane faces. The crystal is mounted on the stem of a goniometer head (Fig. 13) by means of wax, shellac, or plasticine a beam of parallel... 

Fig. 15. Determination of the probable shape of the unit cell from interfacial angles.

CRYSTAL HABIT. The external shape of a crystal, which depends on the relative development of the different faces, as well as upon the interfacial angles characteristic of ihe crystal. 

A pure quartz standard is best obtained by grinding a clear quartz crystal. The quartz crystal can be identified by its characteristic form and interfacial angles according to Stenos law (21). Quartz crystals can be obtained from Ward Scientific (22), or other reputable supplier of mineral specimens. Data on siTTca minerals is given by Fronde 1 (23). 

A repeat of Fig. 2.4.) The primitive direct-lattice unit cell in a triclinic (lowest-symmetry) crystal is an oblique parallelopiped with sidesa, b, c, interfacial angles ot, ft, and y and unit vectors ea, eb, and ec. 

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