6
votes
2answers
103 views

Are there materials that get softer with temperature decrease?

Could be there material that begins melting/softening when it's temperature is lowered? I would say no, but I've seen enough physics to know that not always life is so easy. Moreover I think I've ...
3
votes
1answer
47 views

How can one reasonably theoretically model polycrystalline materials?

Many techniques are taught in advanced solid state courses but they are almost all derived for perfectly crystalline materials. For example, band structure really only appears theoretically when you ...
1
vote
1answer
56 views

Why can't a dislocation terminate in the bulk?

We are told that they can only terminate on surfaces, grain boundaries or other dislocations but we are not told why they can't terminate inside the crystal.
2
votes
1answer
76 views

What does (001) Silicon mean?

If someone gives me a thin film of Si, and they tell me it's (001) Si, does that mean that the (001) planes of Si are the ones making up the surface of the film?
0
votes
1answer
136 views

Ashcroft Mermin Solid State Eq. 22.15

I recently read a paper on Specific heat of a Classical Crystal: Dulong-Petit law. In Eq. 22.15, I don't understand why the ionic displacement $\mathbf{u}$ and ...
9
votes
3answers
178 views

Are synthetically-produced diamonds as hard as natural diamonds?

I was having a discussion with my friend about the intrinsic worthlessness of diamonds (DeBeers and whatnot) and how synthetic diamonds haven't caught on, again because of the marketing/propoganda ...
1
vote
0answers
74 views

Is there a derivation of all possible Bravais lattices in 2D and 3D?

Do any of you know a (possibly elegant) derivation of all possible Bravais Lattice and the Crystallographic Group of Lattices in 2 and 3 dimensions? Group theory /abstract nonsense approaches are ...
0
votes
0answers
32 views

When does a crystal take the shape of its Primitive Cell?

I know thought that a crystal, if annealed for long enough at high enough temperatures, will "shed" its higher index (higher energy) planes, leaving only its most stable form. This, I wrongfully ...
2
votes
1answer
225 views

Regarding Bravais lattices

There is 'End-Centered' Orthorhombic lattice . Why this type is not in 'Cubic' lattice ? On which basis did Bravais propose his theory ?
1
vote
1answer
203 views

If my lattice has an atomic basis, do I also find the reciprocals of the basis vectors to get the reciprocal crystal structure?

That is what my crystal structure looks like. The blue atoms sit on every lattice point (basis vector of $\{0,0\}$) and the red atoms have basis vector of $\left\{{2\over3},{1\over3}\right\}$. The ...
2
votes
1answer
103 views

Is this 2D structure triclinic?

The only rotation axis obvious to me is rotation by 360 degrees, the identity. Vertical mirror planes I've been dicing and cutting it through several planes and I still see none. Yet, the structure ...
1
vote
1answer
211 views

What would be the basis vectors for this 2D crystal structure?

In the above image, I have a 2D crystal structure. The lattice vectors are described by: a = {-1/2, -Sqrt[3]/2}; b = {1, 0}; and the location of atoms A and B ...
2
votes
3answers
1k views

What is the difference between lattice vectors and basis vectors?

Google has not been very useful in this regard. It seems no one has clearly defined terms and Kittel has too little on this.
0
votes
1answer
134 views

Is there real materials have Lieb lattice structure? [closed]

Is there real materials have Lieb lattice structure? Some examples?
0
votes
2answers
3k views

Wyckoff positions and lattice coordinations

Many papers use Wyckoff positions and Space Groups to report atom coordinates, making use of the structure's symmetries to save space in the notation (e.g. diamond = Fd-3m, only). How can I ...
6
votes
1answer
2k views

Transparency of materials

Is transparency of material has something to do with inter- or intra-molecular bonding? E.g. both graphite and diamond are carbon, but graphite is opaque and diamond transparent.