Sciencemadness Discussion Board

Molten vs crystallized from solution salts - what is stronger?

AsocialSurvival - 10-10-2014 at 18:34

I am curious about resistance of crystals to breaking. Are they stronger if we grow a single crystal in solution or if we melt many crystals together? For example Sodium Chloride and other ionic compounds, and glasses (especially pure SiO2). I know that slow cooling (annealing) causes glass to become stronger - especially resistant to heat, this is because few larger crystals are formed when we crystallize slowly, and more smaller ones when we crystallize/cool/evaporate/precipitate quickly.

Also, is it true that I will get finer powder by quicker crystallization/precipitation? So it will have more surface area and react faster with other substances?

[Edited on 11-10-2014 by AsocialSurvival]

blogfast25 - 11-10-2014 at 06:23

Mechanical strength of a monocrystal is a property inherent to the pure substance the material is made from. Of course most crystallisations don't yield flawless monocrystals, in which case the many fault lines will make the material weaker.

But how these flawless monocrystals are made should have no bearing on their inherent strength.

Quicker crystallisations tend to lead to more and smaller crystals. Growing large monocrystals is always a patience requiring slow labour of love.

Glass is not a crystalline material: it's a super cooled liquid. It doesn't actually melt, it undergoes a glass transition.

[Edited on 11-10-2014 by blogfast25]