Solid State Physics. Philip Hofmann. Читать онлайн. Newlib. NEWLIB.NET

Автор: Philip Hofmann
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Физика
Год издания: 0
isbn: 9783527837267
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we add a remark about symmetry. So far, we discussed only translational symmetry. However, a real crystal may also exhibit point symmetry. Compare the structures in the middle and the bottom of Figure 1.3. The former structure possesses a number of symmetry elements that are missing in the latter – for example, mirror lines, a rotational axis, and inversion symmetry. The knowledge of such symmetries can be very useful for the description of crystal properties.

      After this rather formal treatment, we look at a number of common crystal structures for different types of solids, such as metals, ionic solids, or covalently bonded solids. In Chapter 2, we will take a closer look at the details of the bonding in these types of solids.

Schematic illustration of (a) Simple cubic structure; (b) body-centered cubic structure; and (c) face-centered cubic structure.

      1.2.1 Cubic Structures

Schematic illustration of structures of CsCl and NaCl. The spheres are depicted much smaller than in the situation of dense packing, but the relative size of the different ions in each structure is correct.

      1.2.2 Close‐Packed Structures

Schematic illustration of close packing of spheres leading to the hcp and fcc structures.

      The structures of many ionic solids can also be viewed as “close‐packed” in some sense. One can derive these structures by treating the ions as hard spheres that have to be packed as closely to each other as possible.

      1.2.3 Structures of Covalently Bonded Solids