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Author: Subject: Chemicals for crystal growing
The Volatile Chemist
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[*] posted on 27-2-2016 at 10:15


Quote: Originally posted by Bezaleel  

@Volatile Chemist: I keep wondering about your procedure for crystal growing in silicic acid gel. You say that you combine silicic acid with dilute acetic acid, but silicic acid is a hard substance. Thus it seems like you combined sodium silicate solution (waterglass) with acetic acid and lead acetate solution. But if that is so, then why is there no lead silicate being formed? Or is there, and is metathesis with KI what happens next?

I'm sorry. I didn't actually do the lab in my own lab, but in my AP Chemistry course. yes, it was waterglass we used, and I haven't a clue why the lead silicate isn't formed. Waterglass and silicates in general are rather strange.




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[*] posted on 3-3-2016 at 07:42


Have anyone tried growing crystals of tellurium?
If yes could you post the procedure (I assume they are being grown from melt)
and eventually some pics please?
Thanks.




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[*] posted on 4-3-2016 at 07:21


I did some further research on Mrs. Stewart's bluing, and it appears that it contains Pussian blue, oxalic acid, and ammonia. I am going to attempt to produce potassium cyanide from it, but I'll discuss that further elsewhere as to not hijack this thread.
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[*] posted on 8-3-2016 at 12:50


Quote: Originally posted by Bezaleel  
That's peculiar as you get a lovely hexagonal bipyramid. Wish I had obtained a seed crystal like that! Did this just form in your solution? I only got tabular crystals from K2SO4.

Yes, I took small seed crystal of such form, and it just grew bigger. I also get tabular and stick crystals sometimes, but bipyramidal are more usual.

Actually, that's an interesting question, how K2SO4 can form a crystal with hexagonal symmetry. Wikipedia says that it has orthorombic crystal system, so order-6 symmetry should not be present. However, I remember reading somewhere that this compound is prone to forming cyclic twins, so probably, my bi-pyramid is not a single crystal, but 3 twinned crystals.

By the way, here is another compound that crystallizes really well: glutamic acid hydrochloride. I measured solubility to be around 50g/100ml. Finally, I have found some application for the sodium glutamate from the Chinese species shop.

DSC01775.JPG - 492kB
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Bezaleel
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[*] posted on 11-3-2016 at 03:42


Quote: Originally posted by crystal grower  
Have anyone tried growing crystals of tellurium?
If yes could you post the procedure (I assume they are being grown from melt)
and eventually some pics please?
Thanks.

Take care not to breathe the Te vapors. Search on "telllurium breath" for more info. User and moderator Woelen once named tellurium a "socially problematic substance" IIRC.

Quote: Originally posted by Dmishin  
Quote: Originally posted by Bezaleel  
That's peculiar as you get a lovely hexagonal bipyramid. Wish I had obtained a seed crystal like that! Did this just form in your solution? I only got tabular crystals from K2SO4.

Yes, I took small seed crystal of such form, and it just grew bigger. I also get tabular and stick crystals sometimes, but bipyramidal are more usual.
Actually, that's an interesting question, how K2SO4 can form a crystal with hexagonal symmetry. Wikipedia says that it has orthorombic crystal system, so order-6 symmetry should not be present. However, I remember reading somewhere that this compound is prone to forming cyclic twins, so probably, my bi-pyramid is not a single crystal, but 3 twinned crystals.
Peculiar, I only got the tabular ones. I'll try again. Did you cool quickly or slowly for the seed crystals?
Quote: Originally posted by Dmishin  
By the way, here is another compound that crystallizes really well: glutamic acid hydrochloride. I measured solubility to be around 50g/100ml. Finally, I have found some application for the sodium glutamate from the Chinese species shop.
Looks great! How did you separate the sodium chloride from your sodium glutamate? Does it just crystallise out first, leaving the glutamic acid in solution if the pH is low enough?

[Edited on 11-3-2016 by Bezaleel]
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[*] posted on 11-3-2016 at 05:10


Iodine

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[*] posted on 12-3-2016 at 07:36


Quote: Originally posted by Bezaleel  

How did you separate the sodium chloride from your sodium glutamate? Does it just crystallise out first, leaving the glutamic acid in solution if the pH is low enough?
[Edited on 11-3-2016 by Bezaleel]

Opposite of this. Glutamic acid has relatively low solubility (0.8g/100ml). I precipitated it with stoichiometric amount of sulfuric acid (cheapest acid I have), washed with cold water and then dissolved in HCl. Need to say that precipitate is rather bulky and washing is not easy.
If sulfuric acid is taken in excess, it dissolves glutamic acid again, probably giving its sulfate, which does not crystallize well (very soluble, forms syrup-like solution).
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[*] posted on 14-3-2016 at 15:31


Quote: Originally posted by crystal grower  
Quote: Originally posted by Velzee  
Chevreul's salt, anyone? xD
By the way; those are some beautiful photos!

[Edited on 1/10/2016 by Velzee]

[Edited on 1/10/2016 by Velzee]

Chevreul's salt is almost top secret :D u cant even find it on wikipedia.
I'd like to growCu3(SO3)2 crystals too but i dont have sodium metabisulfite to prepare chevrls salt.
Do you know where could I buy it ??


Oops! I forgot.
This is where I bought my sodium metabisulfite.

[Edited on 3/14/2016 by Velzee]

[Edited on 3/14/2016 by Velzee]




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[*] posted on 19-3-2016 at 02:57


This is my article about growing pottasium dichromate crystals.
It is easy to do and crystal u will get are really nice :).

http://chem.pieceofscience.com/?p=937




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[*] posted on 1-4-2016 at 14:49


Nice. I was just realizing how hard it is to grow nice crystals of most chlorides (non-trans. metal). I had some magnesium chloride and strontium chloride sitting out to crystallize, and although both formed crystals, it seemed impossible to dry them. So I'd rule out them for growing any good crystals.



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[*] posted on 4-4-2016 at 14:07


Great topic, good reason to get out of lurk mode for once - first post!

Here's a good old potassium aluminium alum crystal, the longest side is now 48 mm. Slow evaporation method, this one took > 6 months.
The photo doesn't do it justice!




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[*] posted on 4-4-2016 at 20:48


Wow, that's gorgeous, it looks like huge diamond :).
Did you do something to prevent it from dehydration?
If not, do it right now! :) It would really pity to lose this one.




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[*] posted on 5-4-2016 at 06:14


Cucurbit, that is a really beautiful crystal, like having your own pyramid, without have to travel to Egypt. Great job.

My favorite crystal is a chunk from the end of a silicon boule, about 5" in diameter, that looks like a giant Hershey Kiss. I got it from a place that made silicon wafers and it was supposed to be recylced back in to the melt, but someone there gave it to me as a gift. I have a few 3" wafers as well, never got any intact 5" ones, they were too valuable.
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[*] posted on 5-4-2016 at 08:59


Thanks guys!

Yes, I should put it in a jar when ready to protect it from dehydration, but it will be in its growing bath until it's... hmm, 6 cm mayby. A few days ago and I dropped it - can you believe it :o ... The tip broke off and has to regrow!
But chrome alum is probably more vulnerable to dehydration, the crystal at the right had almost completely degraded to a light purple powder, but I managad to re-grow the remaining core into its original shape. Remarkable how it seems to have a memory!

Also, a picture from some NaCl crystals I'm growing from sea salt. It's a difficult compound to grow into nice crystals but it's possible. I suspect the clumping agent (often ferrocyanide) in ordinary table salt prevents proper growth, it's like a negative catalyst. I hope I can grow these to a few cm, they are like architectural models!



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[*] posted on 9-4-2016 at 17:58


Really nice crystals Cucurbit!
I recently decided to try making some sample crystals of the shape of copper sulfate, to demonstrate its crystal habit (for fun mind you). Although I initially had some seed problems, I'm growing from a good sized base seed right now. I've always liked crystals but haven't really tried making any big ones till now. Going to be trying some of these in this thread later, perhaps...




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[*] posted on 9-4-2016 at 20:36


Anyone for NaI(Tl)? I would be curious how one would go about growing one of some size for a scintillation crystal.
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[*] posted on 10-4-2016 at 12:51


Tin Ii chloride! When you run a current through it you get tiny crystals of tin.
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[*] posted on 10-4-2016 at 22:26


Quote: Originally posted by 100PercentChemistry  
Tin Ii chloride! When you run a current through it you get tiny crystals of tin.

I tried this too and got nice crystals of 2-3cm in lenght. Unfortunatelly, they were very delicate and I wasnt able to get them from a solution.




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[*] posted on 14-4-2016 at 05:50


Quote: Originally posted by Cucurbit  
Great topic, good reason to get out of lurk mode for once - first post!

Here's a good old potassium aluminium alum crystal, the longest side is now 48 mm. Slow evaporation method, this one took > 6 months.
The photo doesn't do it justice!






Jesus that's a whopping crystal. I bet that photo doesn't do it justice! What do you grow crystals of such size in? I'd like to hear more from you about your methodology. I know overall it doesn't change much but still, damn son that's nice.




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[*] posted on 14-4-2016 at 08:48


Tnx! I'm using a tray from soft plastic, intended for heating microwave meals. Hydrophobic plastic is better than glass because there is less chance of crusts creaping up at the walls. I'll soon have to buy a bigger one :cool:

Weekly maintenance consists of filtering the solution and replenishing what was lost due to evaporation. I cover the tray with a 'roof' of paper to protect it from dust and slow down evaporation. It's standing in a small unheated unused room with a rather constant temperature. The rest is just 'neglect tek' :)

I'm glad to see the big one's tip has already grown back in a week!


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[*] posted on 15-4-2016 at 12:16


Quote: Originally posted by Cucurbit  
Tnx! I'm using a tray from soft plastic, intended for heating microwave meals. Hydrophobic plastic is better than glass because there is less chance of crusts creaping up at the walls.


Wow, that's a pretty good idea. Never ever would have thought of using a plastic tray to fix that issue, which has actually been quite a pain in the ass for me recently.




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[*] posted on 15-4-2016 at 14:11


Quote: Originally posted by Chemist_Cup_Noodles  
Quote: Originally posted by Cucurbit  
Tnx! I'm using a tray from soft plastic, intended for heating microwave meals. Hydrophobic plastic is better than glass because there is less chance of crusts creaping up at the walls.


Wow, that's a pretty good idea. Never ever would have thought of using a plastic tray to fix that issue, which has actually been quite a pain in the ass for me recently.



I have to admit it wasn't my idea, I just read it somewhere, applied it and it seems to work!

And it's logical: the more water-repellant the container is, the better.
Glass attracts water, the meniscus is hollow, the solution tends to creep up by capillary suction and evaporation at the crusts's high surface area... a positive feedback loop.

It's no guarantee, without a paper cover I still got crusts, but I hope it helps :D




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[*] posted on 18-4-2016 at 01:03


I've found another easy method to avoid crust growth: apply automobile rain repellent to the glassware. I bought a bottle in a nearest automobile accessories shop, and it works really well (btw it works on glass much better than on plastic). According to the label, the rain repellent is made of silicone and isopropanol.
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[*] posted on 26-4-2016 at 06:23


Quote: Originally posted by Dmishin  
I've found another easy method to avoid crust growth: apply automobile rain repellent to the glassware. I bought a bottle in a nearest automobile accessories shop, and it works really well (btw it works on glass much better than on plastic). According to the label, the rain repellent is made of silicone and isopropanol.


Hm, I think I've seen somewhere about using rain repellent. However, once you get it on, could it easily come off? I'm assuming that if it is silicone and isopropanol, then the isopropanol is probably the main solvent for the silicone and evaporates off. But what if you have a little alcohol in your solution to get it more saturated? Could it dissolve the silicone?




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[*] posted on 26-4-2016 at 09:00


Some pretty K2Cr2O7 crystals.

P4263602.JPG - 3.7MBP4263607.JPG - 3.2MBP4263608.JPG - 3.1MB




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