Sciencemadness Discussion Board - The art of crystallization

The art of crystallization

Fantasma4500 - 28-9-2016 at 05:55

so not long time ago i got this idea of using a coffee thermocan for maximizing cooldown stability, which i had an idea of would give me better luck with forming big crystals
so i followed the idea, and as im currently messing about with ammonium phosphate i tossed a hot solution of impure ammonium phosphate into a thermo coffee can along with a single seed crystal approx 2mm big
opened the thing and i found 2 big crystals in there, one of them as big as FOURTY MILLIMETRES weighting just about 15g, supposedly mono-di ammonium phosphate
http://puu.sh/rqGrd.jpg

im thinking about constructing an even better container, aerogel seems to be the best option of insulation, styrofoam scoring just around 4 in insulation, there is also polyurethane which can be around 6, but aerogel up to 12, but for insulation its impotant to have a proper lid to make it airproof which suddenly makes this whole idea more difficult to go ahead and make

in short.. i found the holy grail for crystallization, how would one go about reaching higher insulation efficiency along with more capacity?

MrHomeScientist - 28-9-2016 at 06:26

Aerogel would be good for insulation since it's mostly air. Even better of course would be to remove the air entirely, and use a vacuum insulated flask.

What do you mean when you say Styrofoam is a "4", etc.? What is that number based on?

Fantasma4500 - 28-9-2016 at 06:36

https://en.wikipedia.org/wiki/R-value_(insulation)

yes vacuum has up to 50 in r-value.. but im thinking its gonna first up be expensive to get anywhere near, im looking for widemouth screwlid container, and that would probably come without insulation if its even possible to find, so i think it would lose a lot of efficiency on the lid itself

Sulaiman - 28-9-2016 at 06:39

You could also put a large thermal mass around the crystalisation vessel then insulate that.
Water forms a good thermal mass.

Fantasma4500 - 28-9-2016 at 06:51

the concept would work, but practically it would be a mess having to heat up x litres of water and weight the container down, very slow cooling also works wonders to get very pure crystals as less impurities gets trapped in the crystals so not only as a smaller experiment once a week this would be desired to be used but many times in a day, now using this technique for purification would be more doable if a big container able to fit several beakers or likewise inside of it was possible

NedsHead - 28-9-2016 at 07:04

They make vacuum flasks for soup with a wide mouth, the most popular brand here in Aus are made by Thermos http://www.thermos.com/product_catalog.aspx?CatCode=FOOD

Fantasma4500 - 28-9-2016 at 07:27

thermos seems to be limited to 1L
maybe a widemouth thermocan could be used then the screwlid part could be stucked together with a larger homemade insulated chamber?
what would be important for a screwlid would be it being able to be very airproof once sealed as that plays a major role in keeping the heat inside of the container

Texium - 28-9-2016 at 07:43

Hydroflask makes 64oz (almost 2 liter) insulated bottles. These things can keep ice water icy for several consecutive days. They're really good. Only issue is that it may be difficult to get larger crystals out of the mouth of the bottle.

https://www.rei.com/rei-garage/product/108988/hydro-flask-wi...

phlogiston - 29-9-2016 at 00:36

An oven with a thermostat can be cooled down at a controlled and well-defined rate, and the total dimensions could probably be made smaller than a solution requiring a lot of insulation and thermal mass.

crystal grower - 29-9-2016 at 04:49

Quote: Originally posted by phlogiston

An oven with a thermostat can be cooled down at a controlled and well-defined rate, and the total dimensions could probably be made smaller than a solution requiring a lot of insulation and thermal mass.

I also think that's a best way to go.

Dr.Bob - 29-9-2016 at 06:12

You could use foam in a can and insulate nearly any container, or even build a box of 4" styrofoam, then put any container in the middle and foam the remaining space to save money. I have done resolution crystallizations using an oil bath before, and they are a nightmare to keep consistent, the unevenness of an oven or oil bath can lead to terrible conditions, much better to use a well insulated container, where there is little convection or conduction in the liquid. If I had it to do over, I would build a giant thermos for it. Or use a large Dewar flask.

Fantasma4500 - 29-9-2016 at 10:52

im thinking about just getting a gigantic brick of styrofoam and then ramming some wooden box around it for durability, but again im thinking the pressure from the hot solution could be a problem, most crystallizations dont require much past 100*C so a metal plate on the bottom of this hollowed out styrofoam brick would probably not even be necessary, wood would be a good alternative tho, low heat capacity
styrofoam would be very difficult with solvents such as acetone however, maybe the idea for this styrofoam box would simply be to get a HDPE container with screwlid, widemouth and then stuff it into this styrofoam brick, then make a lid with styrofoam glued to a wooden plate and make it so that you can tighten the lid onto the sides of the box?

now an oven would indeed be the best, but that would crave a bit of insulation as well, mineral wool would work for that, another problem with an oven would be making sure it doesnt actually fluctuate in between temperature but rather very smoothly transist in temperature, i suggest maybe a water bottle with heater and thermostat, then insulated box for this, the water would then deliver the temperature difference SMOOTHLY with rather low heat radiation -- low heat fluctuation
mineral wool would be ideal if were talking very hot heating elements such as in regular ovens or toasters

for an easy solution hydroflask seems to be a very great choice

maybe for a styrofoam box one could create vacuum that would keep the box together, supposing that wouldnt mess up the whole crystallization process somehow, maybe a closed container would be required for that as the water vapour would fill out the vacuum?

what really got my attention about ammonium phosphate was that seemingly the tri-ammonium version, which is thermally unstable seems to form some really nice prisms, i think it would be pretty rad for make one gigantic prism, as in out of naturally grown crystal -- not like quartz prism that has been cut
http://puu.sh/rs3yG.jpg

phlogiston - 29-9-2016 at 12:07

If you have not already, you might enjoy seeying the impressive potassium dihydrogen phosphate crystals they grew for the optics in the National Ignition Facility:

Descriptions of the methods that were used to grow these can be found online.

Fulmen - 29-9-2016 at 12:59

What The Actual Flying FUCK? That is insane. And gorgeous.

Fantasma4500 - 30-9-2016 at 23:43

https://www.youtube.com/watch?v=l_USYub3djY

interesting, i got hold of some gigantic motor about half a year ago, crystal growth it could be used for i guess? with this scale the temperature is a lot easier to handle, its difficult to make the whole thing drop in temperature rapidly
i think its very interesting that phosphates containing phosphor -- which is necessary to all life, has a habit of forming obelisk-like crystals

Dwarvensilver - 9-10-2016 at 11:56

Greets all,
I came across some 24V motors that run at 6 RPM and apparently old clock motors run at 1 RPM (I.E. second hand

) but have not tried an old clock motor yet.
Anyways it is another way to rotate your crystals while growing and I found that it seems to make better looking single crystals.
It is somewhat simpler than trying to build a chamber like for the potassium dihydrogen phosphate crystals.
Here is a link to a video of my largest alum crystal recovering from a bad melting period spell
http://vid901.photobucket.com/albums/ac220/Dwrvnsilver/Chemi...

[Edited on 9-10-2016 by Dwarvensilver]

Fantasma4500 - 13-10-2016 at 05:32

i did wonder about this whole spinning thingy, with the KHP crystal the whole container appeared to be spinning, solution, and even the crystal which appeared to have been placed flat on the bottom, in which i dont really get the whole concept of spinning to give anything in addition, others than trouble?

managed to scavenge some gigantic machinery motor weighting towards 20kg which i havent yet tried powering up yet, with some tweaking it could probably be pretty ace for crystallization.. i see your crystal is hanging in solution while the solution and container is spinning, what do you have to say about the spinning KHP crystal chamber tho? i really hate the idea of having a string stuck inside of the crystal itself, also the hanging string kinda makes it more difficult with an insulated crystallization chamber

Dwarvensilver - 15-10-2016 at 09:37

Hi Antiswat,
I am not sure why they spin the KHP container, I assume it has something to do with getting a better formed, clearer giant crystal. I noticed in the time lapse of the KHP crystal that it gets the spin reversed, again not sure why.
In my set up I have the crystal hanging on a 7x fishing filament which has several pounds strength and only .004", it is like hair and hard to see inside the crystal.
The crystal is hung from a loop on the motor gear and rotates @ 6 RPM.
The pictures show it better
[img]

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[img]

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DraconicAcid - 15-10-2016 at 09:44

I tried using fishing line a few times- I found it impossible to tie without it simply untying itself. I probably needed much thinner line.

Dwarvensilver - 15-10-2016 at 15:21

Well Draconic Acid,

I just about gave up on fishing line because of the same issue lol.
I found that if you use the first part or all of a doctors knot.

[img]

[/img]

When you make a loop, pass the end through twice instead of once (bottom of knot in pic) and it usually holds pretty good.
The more times you do it the easier it becomes

Fantasma4500 - 19-10-2016 at 06:03

i suggest inserting a water bubbler into the solution would also agitate it, maybe if air was blowing onto the surface it could create a circular movement of the solution, the agitation with airbubbler immersed in solution COULD very possibly create some uneven crystallization

if you need to thin down a line a bit you could maybe run some sandpaper over it, i really hate the idea of knowing there is just a tiny bit of something inside the crystal that is not crystal itself

maybe another idea would be an insulated box with a weak fan running to pull air in and out, i still really like the idea of forming a 40mm crystal within 24 hours, it is a bit less passive than hanging a crystal in a beaker but my worries is that temp fluctuates too much in my room to feel comfortable with my precious crystals being left all by themselves in such hostile environments

i do imagine if you can spin the crystallization solution in an UNEVEN pattern, if you imagine the solution will then at an uneven frequency so that the crystal and the solution will collide, and thus making the crystallization take place faster, it may be that crystal and solution will both hit constant still however, hm.
if i had been running their little KHP crystal project i would def had been spinning the solution itself and not entire container

for tightening a line onto crystal i think the method that would involve least line going lost in the crystal would be simply gluing it to the crystal, epoxy or superglue or similar which would have high strenght and wouldnt require a whole lot, also taking into consideration that it would be able to deal with being in water

Sulaiman - 19-10-2016 at 07:48

a few thoughts;

if you spin the container, the more dense (concentrated) solution will be at the outside,
with the solution nearest to the crystal being the least concentrated,
so you will get a beautiful crystal lined container

few temperature controllers can ramp down TEMPERATURE with no short-term rises,
tuning a pid would be boring.
I think that slowly ramping down the heating POWER would give a smoother cooling curve,
but with greater ambient temperature influence.

based only on what I have read, roughening the surface of a thread (nylon monofilament) with sandpaper to thin it down
would cause crystals to grow all along the thread.

an 'ideal' thread would either have the same colour and refractive index as the crystal
or be easily dissolved out and replaced with a filler of the same colour and refractive index.

Edit: Or maybe Fleaker could supply 1.5 um diameter Wollaston wire https://en.wikipedia.org/wiki/Wollaston_wire

[Edited on 19-10-2016 by Sulaiman]

Dwarvensilver - 19-10-2016 at 10:32

A few more thoughts,
yes theoretically the density of the solution would be greater at the outside of a spinning container, but in order to make an appreciable difference I think you would have to spin the container extremely fast to throw it out of wack to the point of only lining the inside of the container, and they do spin the giant laser KHP crystals and it seems to work

All temperature controllers even once on temperature will give a sine wave in the temperature as waters heat capacity is so great and controllers are only as good as the money you throw at them lol.

yup sanding down filament will cause crystal parasites, even smooth mono-filament that I use get parasites.
I understand, being a real pick ass, not wanting to have foreign bodies in your crystals but at least when you use 0.1mm mono-filament it is nearly impossible to see.

Spinning the crystal is quite easily done and seems to give quite good results, but I have only tried it with two crystals to date but they seemed to grow smoother and faster that way.

I am also growing on a hotplate/stirrer set at 30°C which gives a reasonably constant 25°C temp in the growing environment, this may also speed up the growth rate due to more evaporation. I did this due to fluctuating room temperatures.

Last night I put a tiny stir bar in a 2L beaker of alum solution and set it at 60 RPM (lowest setting) with the crystal rotating at 6 rpm as well but this morning I has an alum crystal covered with powdered alum as the extra formed crystal particles could not settle and built up on the main crystal from staying suspended.

wg48 - 19-10-2016 at 13:07

Its something similar this is how they made those huge KHP cystals. The rotation is to power a turbine that circulates the solution.

From https://lasers.llnl.gov/multimedia/publications/pdfs/etr/198...

turbin.jpg - 23kB

Here is a link to an other paper

https://www.cambridge.org/core/services/aop-cambridge-core/c...

[Edited on 19-10-2016 by wg48]

wg48 - 20-10-2016 at 09:16

This is the best paper:
https://www.researchgate.net/publication/238119403_Rapid_gro...

From the paper a continuous filter sytem

Dwarvensilver - 20-10-2016 at 18:53

Thanks for the links, I have the PDF now and will read.
I looks amight complicated to put together,

Hmmm 1000L flask eh, Think Dr. Bob can get one?

wg48 - 21-10-2016 at 08:20

Quote: Originally posted by Dwarvensilver

Thanks for the links, I have the PDF now and will read.
I looks amight complicated to put together,

Hmmm 1000L flask eh, Think Dr. Bob can get one?

Yes its lot more complicated than leaving a solution to evaporate slowly.

Initially I was curious as to how they managed to grow such large perfect crystals in months and not years. Their method does seem achievable in a diy/garage setting. Not necessarily with 1000l of solution but say 5l should be achievable. Its not much more than temperature control and circulation with filtering.

The growing chamber could be polypropylene with peristaltic pump for circulation. If a sub micron filter is required that could be expensive as it will need to be large to get a reasonable flow rate.

To prevent nucleation the circulating solution prior to passing through the pump and filter needs to be heated above the saturation temperature of the solution. It must then be cooled back down to the chamber temperature before reentering the chamber. That will be relatively easy provided the chamber is above ambient.

The chamber will needed to be temperature controlled below the saturation temperature of the solution, perhaps with an external water bath. The obvious problem is as the solution becomes dilute the growth rate will reduce but not until the crystal is a signicant fraction of available solute.

The papers explains nucleation theory and give various methods to prevent it.

I would like to make a big sodium thiosulfate crystal. The hexagonal crystal habit would look nice. Its solutions do not readily nucleate so it should be easy even with mild filtering.

Dwarvensilver - 21-10-2016 at 11:06

Well I could put it up there with my growing list of unfinished projects I suppose

, but I really don't have room for even a 5L set up.
My current crystal room is at work by the grace of my superiors

and I don't want to push my luck lol.

Sodium thiosulfate hmm, I will look and see if we have some kicking around.
It does not desiccate as easily as sodium sulfate does it, my last attempt at growing one resulted in a great crystal that slumped into powder in a very short period.

Fantasma4500 - 22-10-2016 at 00:11

as i managed to produce a very large amount of ammonium phosphate the solution now stays hot for much longer, and a trick is to take a saturated solution that isnt near 100*C but rather just about 60*C, as the initial cooldown will last longer, as the sorrounding atmosphere is closer to the solution, filled thermocan halfway up and it has now been staying hot for a few days

now im thinking of a very simple way to keep the heat, a styrofoam box, within a styrofoam box, the outer part with hot water, although i still really dislike having to handle water, but it would also be quite the hassle to load a steel cylinder or brick into an oven and having it heat up over the course of a day to serve as heating source in outer layer box
now this time i got a pretty big crystal, millimetres bigger and i wouldnt have been able to get it out of the thermocan but it appears to be a mix of di and triammonium phosphate

1000L flask? "smuv" is your man.
http://www.sciencemadness.org/talk/viewthread.php?tid=24908&...

edit: found polyurethane containers
https://www.tedpella.com/cryo-supplies_html/Cryo-compatible-...

[Edited on 22-10-2016 by Antiswat]

Fantasma4500 - 28-1-2017 at 02:19

very long time ago i decided to buy 100 melamine sponges as the chemical compound itself has some potential, it is quite heat resistant and to my surprise it has a very high r-value, relatively so, what is very interesting about these sponges is that you can use it as building blocks, its very heat resistant, easy to cut and can yet hold up to some wear
r-value of 5, super cheap over ebay

Fleaker - 10-2-2017 at 18:08

This was a fun thread to read!

I need to do some crystallization work on K2TaF7.

I've been charged with getting large crystals that are easily washed and especially easily dried before crushing and being reduced with sodium to the metal.

Less occluded moisture means less H & O in the Ta metal--a good thing for my purposes!

Fantasma4500 - 20-2-2017 at 09:04

i found this "gem" at 4m 38s, a sort of sophisticated setup for crystal growing, i really fancy the shape of alum crystals too, and where i live that is available OTC

https://youtu.be/oz2MlC9pg7c?t=4m38s

i have found it also that a seed crystal can be glued onto a stick or whatever, then be inserted into the solution to be grown, the string i have keeps untying itself and even breaks after a week of crystallization, it also appears to me that a crystal when glued to something facing downwards in the solution appears to be growing more downwards than expanding sideways, not sure if this is just a faulty observation or something that happens only with monoammonium phosphate

K2TaF7 sounds exotic, please do post if you get interesting results
im pondering to add pictures to all wikipedia chemical pages of the respective chemicals in their crystal form, would make wiki pages a little bit more interesting to walk through