Crazy Crystal Structures Trivia Quiz

Answer: 14

Yes there are 14 different space lattices (organized in seven systems) that could be formed. A space lattice is a small primitive cell that can be repeated potentially an infinite amount of times to form the macro crystal structure.
In a space lattice there are three dimensions and four angles to be considered. Each space lattice will have three corners. See if you can guess all the possible combinations.

Answer: Two axes are the same, one different.

The tetragonal crystal structure is one that looks like a 3D rectangle with all angles at 90 and two pairs of different lengths. It makes up 2 of 14 space lattices. These are the simple tetragonal and the body centered tetragonal.

Answer: 2 fold,3 fold, 4 fold, 6 fold.

Only 2, 4, 3, and 6 fold crystal symmetries are possible. If you pause for a second and try and fit regular pentagons together ( 5 fold ) you will soon notice gaps emerging. Do the same with and symmetry over 6 fold and you will find overlaps. It is important to note that mathematicians have found ways to fit in 12 fold symmetry by using a series of kites and darts, however this doesn't occur in nature.

Answer: Polarization

Polarization is the distortion of electron clouds by cations and although it disrupts the maths in which the atoms are assumed to be spherical is is by no means a defect. A vacancy can be imagined as a place where an atom should be but isn't. Interstitials are atoms which have been dislocated by some means and now reside as an impurity between the lattices. Dislocation is when a lattice has been moved so it sort of wedges itself between the other lattices.

Answer: The movement of lattices

In fact the other three would increase the level of stress in the crystal. It is the movement of lattices that relaxes stress as this requires energy so the stored energy due to the stress applied is dissipated.

Answer: Glass

Although it may at first seem strange, glasses are the least crystalline structures that can exist, i.e. they have the highest entropy. This is because a glass is made by super cooling a liquid. As it cools the atoms lose the energy that they require to move so they stay where they are. This gives you a solid structure with the entropy of a liquid.

Answer: Vacancies and Interstitials

In a nuclear reactor, large fission fragments are crashing into the graphite rods all the time. They have such high energy that they break the crystal structure and cause atoms to be pushed into the crystal structure forming vacancies and interstitials, These interstitials have an amount of stress stored.

When one of them comes into contact with a vacancy it will move giving out that stored energy as heat. This can cause the rods to overheat.

Answer: Quadrahedral

The 7 crystal types are as follows:
- Cubic
- Hexagonal
- Tertagonal
- Trigonal
- Orthorhombic
- Monoclinic
- Triclinic

Answer: The three angles and lengths are different from each other

In a triclinic crystal structure, all angles and lengths are different. If all angles were the same and all the sides different, this would be an orthorhombic crystal structure. Stating that they cannot have defects is incorrect as all crystals can have defects!. Also, although some radioactive elements may have this crystal structure not all do. Uranium, for example, is orthorhombic.

Answer: Phonons

Phonons are the vibrations that carry heat in a lattice. they are made up of waves that move around the crystal structure. Although ions could potentially move in vacancies and conduct heat that way it would be an insignificant amount. Otherwise the ions could not be free unless the crystal was dissolved. In metal crystals free electrons do conduct heat but they are not the main conductor. On the subject of diffusion as I said with the free ion, heat could travel this way but it would be in insignificant amount.