Does melting deteriorate the crystalline order?

[Si14]

I wonder if melting deteriorate the crystalline properties and order of a solid?
For example, one should expect to get 2 different Raman spectra from the solid and melted samples?

 

[alxm]

I suppose you mean recrystallization rather than melting - obviously the molten (liquid) phase has very different properties! As for whether a recrystallized substance has different properties, that'd depend entirely on the substance, (and whether it has several phases, for instance), the original state and if the recrystallization conditions match the original crystallization conditions etc.

But recrystallization does not at all necessarily degrade the crystal. Often the contrary, which I'd almost have expected you to have known, with that username: The high-purity monocrystalline silicon used in solid-state applications is purified by repeatedly melting it! (Zone melting, which works through the fact that the impurities have a higher solubility in the liquid phase)

 

[BANG!]

I wonder if melting deteriorate the crystalline properties and order of a solid?
For example, one should expect to get 2 different Raman spectra from the solid and melted samples?

Well, if it is in a melted form then this is clearly different than the crystalline form. However, at the macroscopic level most crystals are not one big repeating single crystal. Rather, it is made of millions of small microscopic domains of aligned repeating unit cells that are randomly oriented. Often we refer to these crystals as "powders" even though they may be a hard chunk of whatever. Thus, a powder is isotropic in a very similar way as a liquid. A major distinction though would be that elastic powder peaks due to Bragg scattering would disappear upon melting and inelastic excitations would no longer be lattice dependent. Let alone the fact that a major shift in temperature will typically have considerable impact on measured spectra, regardless of the crystalline form. Especially when the temperature approaches the energy scale of the coupling energies driving the order in the system.

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[BANG!]

I suppose you mean recrystallization rather than melting

Good point. I expect you meant recrystallized, not still melted. alxm covers this interpretation of the orginal post well so I won't add much, except to say that quite often crystal growers begin by forming a sintered powder then they melt and cool this powder back down so as to get a single crystal. This is actually quite difficult and typically require high specialized ovens such as a floating zone furnace.


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