University of Cambridge

Cake crystallography

This discussion was inspired by Omar Shah and Sarah Martin, both Part III Natural Sciences students 2020 at the University of Cambridge, U.K., and Soraya von Willingh from the University of Cape Town, South Africa.

We attempt here to illustrate symmetry and crystallography as seen on birthday cakes. You might argue that we are being approximate, but there are in fact no crystals with long-range periodicity. For example, a solid solution that is crystalline has a mixture of atoms not arranged periodically, and yet, we call it a crystal. Even an atomically ordered crystal will have defects and therefore does not satisfy the concept of long-range periodicity. Crisis of confidence? Cakes can do that.



Omar Shah, Sarah Martin, University of Cambridge, Soraya von Willingh, University of Cape Town, Harry Bhadeshia, cakes, crystallography, symmetry
This cake, baked by Sarah Martin, illustrates twinning, with the crystal planes reflected across the twin boundary. Definitely a Type I twin, not mechanical because it does not have a lenticular shape. A consequence of the heat-treatment leading to annealing twins. 		Omar Shah, Sarah Martin, University of Cambridge, Soraya von Willingh, University of Cape Town, Harry Bhadeshia, cakes, crystallography, symmetry
Here there are mirror plane paralllel to the vertical axis.
Omar Shah, Sarah Martin, University of Cambridge, Soraya von Willingh, University of Cape Town, Harry Bhadeshia, cakes, crystallography, symmetry
Clearly a screw axis normal to the broad plane of the cake. In fact, a screw hexad. 		Omar Shah, Sarah Martin, University of Cambridge, Soraya von Willingh, University of Cape Town, Harry Bhadeshia, cakes, crystallography, symmetry
EBSD cake made by Soraya von Willingh (in the foreground), University of Cape Town, South Africa, in honour of Karine who was leaving for Brazil.
Omar Shah, Sarah Martin, University of Cambridge, Soraya von Willingh, University of Cape Town, Harry Bhadeshia, cakes, crystallography, symmetry
EBSD stands for electron back-scattered diffraction. The junctions between the grain boundaries on the cake are not at equilibrium. Soraya has many other creations related to cakes and is the Scientific Officer at the Centre for Materials Engineering. 		Omar Shah, Sarah Martin, University of Cambridge, Soraya von Willingh, University of Cape Town, Harry Bhadeshia, cakes, crystallography, symmetry
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