CsClähnliche

CsClähnliche (cesium chloride-like) describes a structural motif found in certain crystalline solids, particularly in inorganic compounds, where the arrangement of atoms resembles that of cesium chloride (CsCl). In this structure, each cation is surrounded by eight anions, and vice versa, forming a body-centered cubic (bcc) lattice. This coordination number of eight is characteristic of CsClähnliche structures, distinguishing them from more common sodium chloride (NaCl)-type structures, which feature a coordination number of six.

The CsClähnliche structure typically occurs when the ratio of cation to anion radii is relatively large, favoring a higher coordination number. This arrangement is often observed in compounds where the cations are large and the anions are small, such as CsCl itself, as well as other alkali metal halides like NH4Cl (ammonium chloride) and TlCl (thallium(I) chloride). Some binary metal compounds, such as ReB2 (rhenium diboride), also exhibit this motif under certain conditions.

Unlike NaCl structures, which are stable at lower temperatures, CsClähnliche structures are often favored at higher temperatures or pressures. The transition between these structures can be influenced by thermal or mechanical stress, leading to phase changes in the material. This structural flexibility makes CsClähnliche compounds interesting for studies in materials science, particularly in understanding how crystal geometry responds to external conditions.

The CsClähnliche motif is also relevant in the study of ionic solids, where it provides insights into the balance between ionic radii, electrostatic forces, and lattice energy. While less common than NaCl-type structures, its occurrence highlights the diversity of crystalline arrangements possible in inorganic chemistry.