# Tag Info

1

How much scatter do you need? Mirrors and corner-cube reflectors are certainly non-Lambertian. Any number of machined surfaces with designed roughness or structure are non-Lambertian, e.g. reflection gratings. Beyond that, if you Google for "BRDF" (bidirectional reflectance distribution function) you can probably track down any number of homogeneous ...

2

Most surfaces are going to be non-Lambertian to some degree. My desk is a good example. There are multiple scattering from the rough wood surface producing Lambertian scattering but there is also specular reflection from the varnished top layer of wood. Lambertian scattering depends on the surface having a sufficiently random level of roughness. Once you ...

1

Plastic deformation is largely due to dislocation motion and is a more general term in materials science. That out of the way I think I still understand your question. In general: plastic deformation occurs when a material is stressed beyond it's yield stress. (this can be in tension, compression, or torsion) Fatigue failure occurs due to continually ...

13

Ice, as in the ice you see in cold weather, is most certainly a crystal. In fact ice has at least 11 different crystal forms depending on the temperature and pressure. The form we see on a cold day is ice 1h. A glass, i.e. an amorphous solid, is a material that has no long range order and shows a glass transition rather than a distinct melting point. It is ...

29

A crystalline substance doesn't necessarily have to be a single crystal to be deemed as such. An amorphous solid such as glass doesn't exhibit a crystalline structure even at very high levels of magnification. Glassy substances have a glass transition phase that is lower than the melting temperature. The melting point of ice formed under ordinary ...

0

In the free-electron approximation, the electron energy is indeed $\frac{(\hbar k)^2}{2m}$ with a minimum at $k=0$. However, in a real material the electron is not free, and feels a background potential due to the distribution of the other charges, which modifies the $E(k)$ relationship. In a material with low symmetry, I presume this can also shift the ...

1

A sharp knife is still several molecules thick on the edge; dull blades are even wider. So when you attempt to cut material, it needs to be ripped apart. As explained in other answers, the material either fractures along faults in the lattice, or you separate molecules (as when you cut bread). The only materials where you might split chemical bonds are ...

0

I guess you mean "silicone-like", not "silicon-like". Recently, I was looking for a similar material (Need an intermediate resistivity part/material ), but eventually obtained doped silicon rods. You have several options, depending on the required geometry and properties of the part. For example, there are so-called "intrinsically conducting polymers" ...

2

The space elevator probably deserves an entire series of questions (and I am sure there have been plenty of posts), but if we stick to this particular version, there are a couple of problems with it. First of all, a space elevator needs a counterweight in an orbit that is higher than the areostationary orbit (the Martian equivalent of Earth's geostationary ...

0

You could try PEBBLES which is freeware AFAIK

Top 50 recent answers are included