Question

What is meant by isotropic, crystalline solids and amorphous solids?

Answer 1

Isotropic means that a certain material will exhibit the same set of characteristics or properties in all directions. On the other hand, an anisotropic substance will display different properties in different directions.

Crystalline solids have a definite geometry which is constant in a particular direction such as A-B-A-B-A-B etc. In such a case vertical layers will have either A-A-A-A-A or B-B-B-B-B when the layers are stacked together. Hence, the substance will display different properties in the horizontal direction and a different set of properties in the vertical direction. Such substances are called Anisotropic substances.

Amorphous solids do not have any fixed geometry and as a result, have random geometry in all directions. The randomness averages out in the larger perspective and hence we can say that it will display a similar set of properties in all directions. This is an example of Isotropic substances.