{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

17 overheads symmetry illustrations

17 overheads symmetry illustrations - Pointgroups:whywecare...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Point groups: why we care Physical properties Point group of crystal is a subgroup of the symmetry group of any of its physical properties. The symmetry group of any property of a crystal must include the symmetry operations of the point group. Enantiomorphism, chirality: The absence of improper rotations (rotoinversion, rotoreflections). In particular the absence of a center of symmetry 1, mirror plan, m=2, and 4 axis. This means the molecules occur as right or left handed (two forms) Enantiomorphic crystals exhibit optical activity information about the point group of a crystal may be obtained by the observation of physical effects. Many interesting physical properties occur only in non centrosymmetric Many interesting physical properties occur only in non centrosymmetric crystals ( piezoelectricity , pyroelectricity, optical activity) Optical properties: Refractive index, optical activity, SHG International Tables for Crystallography (2006). Vol. A, Chapter 10.2, pp. 804–808, BY H. KLAPPER AND TH. HAHN 10.2. Point group symmetry and physical properties of crystals
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
piezoelectricity Initially unpoled Dipoles unaligned material expansion http://www.physikinstrumente.com/tutorial/4_15.html http://www.mnn.com/earth matters/energy/photos/10
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}