Dinammar
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Will this supersaturated crystal growing solution work?
I'm planning on mixing 25 g of neodymium nitrate into 10 - 15 ml of very hot water to make a supersaturated solution of neodymium nitrate. Now this is
obviously too little to make good crystals so I thought that pouring the supersaturated solution of neodymium into a 400 ml supersaturated solution of
potassium/sodium nitrate would still make crystals with a light purple hue. Is this correct? Thanks in advance.
[Edited on 13-7-2016 by Dinammar]
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Artemus Gordon
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I don't understand what you are hoping for. Both KNO3 and NaNO3 are mononitrates while neodymium nitrate is a triple nitrate
molecule, so I doubt you would get crystals that were a mixture of your ingredients. If you allowed your solution to go completely dry you would
probably find two (or 3) different types of crystals sitting separately on the bottom. The shapes of the molecules are too different for them to nest
together in the same crystal lattice. Also, Nd(NO3)3 is the most soluble chemical of the 3, so it would be the last one to
crystallize. In other words, if you had a mixed solution of these chemicals, it would be easy to separate them by crystallization, because the
KNO3 and NaNO3 would form pure crystals while the neodymium would stay in solution.
Also, supersaturation is an uncommon state for a solution to be in. It usually requires careful manipulation of temperature. If you simply try to stir
excess chemical into your water, you will usually get a simple saturated solution with a lot of undissolved powder sitting on the bottom.
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Dinammar
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Thanks for your help. I am planning to make neodymium nitrate crystals but I only have 25 g of it. Obviously this is too little so I'm trying to find
a salt that is compatible for making crystals with the neodymium. I want to make a 400 ml supersaturated solution. Obviously I could add lanthanum
nitrate but it's too expensive. I thought maybe adding aluminum nitrate until the solution is supersaturated and then pouring the supersaturated
solution of neodymium nitrate into it. Will this give me purplish crystals?
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Artemus Gordon
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Al is definitely a better candidate than Na or K, since it forms a +3 ion. However, it is a smaller atom than Nd, and it is more electronegative, so
it probably would pack closer than Nd in a crystal lattice. This may well prevent Al(NO3)3 from joining in a crystal with
Nd(NO3)3 but I have never tried that. I say try it, maybe with only 1g of each salt and see what happens.
Otherwise, keep looking for another +3 ion closer in size and electronegativity to Nd. Maybe another rare earth, although with China's near monopoly
on production, they may all be too expensive.
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Dinammar
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I think indium (III) nitrate would work, but it's way too rare. I was thinking of lead nitrate even though it forms a +2 ion. The molecule is a bit
bigger than neodymium nitrate. The solubillity is 50 g/100 ml of water at 20 dg. Celsius, while neodymium is near 100 g/100 ml. This would obviously
cause troubles but it just might work. A better replacement for lead nitrate would be calcium nitrate. It still forms a +2 ion, but it's solubillity
is very close to neodymiums.
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MrHomeScientist
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Indium's not all that rare; there's tons of it on eBay! Just buy some of the metal and dissolve in nitric acid. I assume that's how you made the
neodymium nitrate.
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Dinammar
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Actually, I got the neodymium nitrate as a gift. Also, I really don't feel like ordering indium from eBay as it would take way too long to be
delivered to my location (I don't live in the US). I could maybe order it from ebay UK but I think a better option is barium nitrate because it's
supper cheap where I live and I think it will work just fine to make a barium-neodymium crystal.
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