What happens to crystalline silicon when you heat it up?

Question

Would the silicon lose it's crystal structure at a certain temperature below its melting point?

Answer 1

Only crystals can melt; amorphous materials are already liquids and cannot undergo melting.  As the melting point is approached, there is enough thermal energy that small crystals can start to rearrange to form larger ones and flaws in crystal lattices can heal (this is the principle behind annealing) and silicon is no exception to this.  So you might start to see changes in the material properties of a block of silicon near the melting point, to go along with the changes in its exact crystalline structure, but that is the primary crystalline effect.

Aside from growth of larger crystals and healing of defects, the primary change that would take place is enlargement of the spacing between the silicon atoms (thermal expansion).  This, in turn, would cause changes in other material properties (heat capacity, diffusivity constants etc.)