freeze precipitate big crystals

[Muttley]

Assuming ona has a very precise way to control a freezer what would be the optimal temperature fluctuation to precipite big crystals from naphta?

For example lowering from room temperature to -20ºC in 24 or 48 hours, and then raising it again to room temperature in another 24 or 48 hours and then repeat this cycle for a week or more.

Could this produce bigger crystals then only putting it in the freezer overnight?

If so, what's the ideal degree per hour? And for how long?

 

[DidMyTest]

As far as I know the colder the solution is the smaller is it's ability to hold the DMT that's why the cristalls fall out. I read the size of the crystalls is dependend on the material they grow on. The handbook tells that if you want to get big crystals the best way is to dissolve the DMT again in a solvent after the freeze precipitation and let the solvent evaporate (also the speed of evaporation is important). If you use a fabric new glass without any scratches you get bigger crystals because they can't grow on a scratch so the molecules attach to the already growing crystal.

The DMT is recovered here by means of slow evaporation rather than freeze precipitation.
The slower the evaporation, the larger the crystals will be. Furthermore, if recrystallised DMT
is used to grow crystals with, you will also find that larger crystals will form. This is because
there are fewer impurities present to interfere with the crystal formation process.
I should mention that the type of glass or container the evaporation is performed in does
make a big difference to the crystal formation. The main factor here is that say you use an old
wine glass which likely has several minute scratches and chips on the inside; these
imperfections in the glass provide the DMT molecules a place to attach to. If your glass is
very ‘imperfect’ then you will find a whole bunch of smaller crystals forming, rather than a few
nice big ones

 

[bindu]

In my expierience, alternating freezing and warming in the fridge gives bigger crystals.

 

[Dozuki]

The slower the solution cools, the bigger the crystals should be.

 

[deeplake]

What about using a seed crystal? I'd like to research, and try this next time.

 

[AluminumFoilRobots]

Something I have found, but do not know to be a fact, is that when freeze-precipitating in regular glass I get crystals of a few millimeters only, however when I have used a precip-vessel that was made of crystal, the precipitated DMT forms LARGE flowery crystals probably a few cm in length. I don't know if this could be that the crystal acts like a seed crystal, or if there is some sort of vibration/resonance from the dish, but I have noticed this repeatedly.

 

[Muttley]

thanks for the replies.

I'll post here future experiments resoults...

 

[JuremaSpaceship]

I understand that larger crystals might be easier to harvest but wouldn't smaller crystals be ideal for vaporizing? It seems like it would melt and vaporize faster if they were light fluffy crystals.