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IrC
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Lanthanide Chemistry (Europium)
For some time whenever I need europium oxide for my glow powders I just take some Eu metal out of the oil, dry it, and put it in a beaker covered with
a paper towel layer, tightly held with a rubber band. This way it will slowly turn into an off white powder (Eu2O3) without any dust or other
contaminants from the air. This I then store in a bottle. Being out, I took a 20 gram chunk from a bottle (marked Eu) which I bought from my supplier
(PS - they don't know which element it is). It very rapidly covered with a greenish powder. Cutting some off, I dropped into a test tube full of
water. With incredible speed the small piece vanished, in fact it instantly turned into an insoluble (or low) yellow compound which after siting all
night is an off white color (no yellow at all) layer at the bottom of the flask, i.e., insoluble in water. The remaining metal is still in the beaker
covered so only clean air can get in, and is vanishing into a beaker full of the same blindingly bright yellow powder.
So my attempt at Eu(OH)3 is making the same thing as the oxide in appearance, the most beautiful yellow I have seen in a chemical. My problem is I
have made europium oxide many times and it is white to off white, some texts say rose. Holmium is very soft and I cannot find a hydroxide reference to
compare so this is the only other element so far that I can suspect it may be. Clearly I bought a bottle full of oil that was supposed to contain 20
grams of europium that must have been mislabled by the seller. It is a very soft metal that looks like europium when under oil but I have never had Eu
form these yellows. Also, the greenish colored coating I have only seen on my one pound blocks of misch metal, which are a lanthanide soup, mostly
cerium. Anyway, looks like no glow powder experiments this week as I still need the Eu but does anyone know for sure just exactly which element this
bottle labeled Eu contains?
There is also the chance that it may be cerium, but with all the mechanical stressing in open air I did to the metal I do not understand why it did
not burst into flames. Also, the greenish coat right after drying it off is also something misch metal has, and that is mostly cerium. So for now I
think most likely it could be cerium, if I could just understand why it did not start burning. While I have some Ce under oil so far I have never
taken it out and done anything with it. As to appearance in the oil, it looks very much like any of half of the lanthanides so it is not possible to
tell in this way. Has anyone played with cerium, is it possible all the bending, twisting, and cutting the dry metal in open air could be done without
it igniting? In any text I read they all state it is likely to start burning by merely scratching it with a knife.
E.by Chemoleo: Title.
[Edited on 20-8-2005 by chemoleo]
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IrC
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Never mind, I must be the only person here who works with lanthanides and actinides.
There is no doubt it is cerium, even if it did take much mechanical abuse in open air without igniting.
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12AX7
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Yeah, I doubt many of us have much for lanthanides, would be interested in learning about their chemistry though. Like...how did the old guys
seperate them without ion exchange?
Tim
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praseodym
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It is nice that you are able to work with lanthanides and actinides, which are some substances most people dont come into contact with. I remember
reading something about europium oxide (Eu2O3) being widely used as a red phosphor in television sets but may I know how does it work?
And...IrC, how do you know that the metal present is cerium? Cerium only forms ions with charges 3+ and 4+. I thought cerium(IV) salts are usually
orange red or yellowish, whereas cerium(III) salts are usually white. Then what will be the greenish substance formed?
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vulture
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Many reactive metals from greenish coatings when exposed to air.
IMHO this is just color diffraction of oxide/hydroxide/carbonate layers.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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IrC
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"Like...how did the old guys seperate them without ion exchange?"
I don't think they did. More like they got 60/40 or somewhere, just enough to get a sense of some new properties.
"IrC, how do you know that the metal present is cerium?"
This is what is so frustrating. The chemicals most of you play with are so cross indexed if they had kids you would know their names beforehand. When
it comes to the L's and A's, nada. Search for days and you get conflicting bullshit. This is one of the most amazing things I have learned
so far, namely the fact that the "authorities" who write all disagree, state incorrect information, and in general are just a bunch of
bullshitters stating "facts" they don't even know. I can go to 9 different sources for characteristics and get 9 different stories
(likewise for the MSDS's). So far all I can surmise is the fact that nobody has really messed with these elements enough to know much at all.
Example, how do I know it is Ce? A guess, when out of it's oil it starts turning into yellow powder. It is squishy in pliers. It does not have
the attraction to a magnet Ho does. Ho looks more like pyrite in color, has the strongest magnetic moment of any element, is not squishy, does not
flake away in air.
Only Ce and Ho form yellow oxides (of the lanthanides at least), but Ce forms more than one, and there is no orange slash yellow. There is orange and
there is yellow, and there is an impure mix of Ce oxides (two valences). So someone writes about it and states orange-yellow. They did not bother to
do an chemical analysis. Someone else does and comes up with two. I guess the best I can explain it is the lanthanides and actinides are still in the
realm of alchemy when it comes to our knowledge of them. I find this strange as I am finding more strange properties than I have ever read about with
all the everyday stuff which makes up the bulk of chemistry. In short this stuff is fun, not so boring, since it is all new.
The problem is trying to gain information. Example, Ho and Ce make yellow oxides, Ce makes a yellow hydroxide, after searching my ass off I canot find
any information on a hydroxide for Ho. So no way to be sure from the color of the hydroxide of holmium. Best I can do is combine the properties I can
find and the most hits must be the correct answer. It sucks as I can find a list of a gazillion properties of compounds of the other elements. Some of
it is lack of facts, some people keep their research secret, and this is especially true for the actinides. For all lanthanides you will see symptoms
like "writhing" and "cardiovascular collapse" in large doses. How large? A large dose of cyanide could be the size of the head of
a pin. Lanthanide LD's for rats usually are 5 grams per kilogram, so at least I believe most lanthanides are fairly safe to play with. As far as
toxicology goes the best I can determine is that it is all about higher valences.
U and Pu are very deadly like P is, but most of the lanthanides are a 3 or a 3 and a 2. But there are many deadly elements outside of this rule like
Cadmium and Thallium so the subject gets more complicated.
Vulture was correct, and in the Ce case once I turned it all into oxide all I had was a beautiful yellow powder. I am still at a loss to understand
why my Ce did not ignite with all the twisting, bending, cutting, and squishing I did. No sparks either. My pound blocks of misch metal though are
hard as hell to cut. Very hard, sparks all over the place and when just a few filings build up a few sparks send it all up in a fireball. You should
try cutting something that is bursting into fireballs sometime. It is actually fun. If I ever get an unburned pile I think I will try some new
experiments on it. Hard to do as I really do not have the right setup to be messing around with much of this but what the hell, it is fun.
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Eclectic
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Maybe it's praseodymium?
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IrC
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"Maybe it's praseodymium?"
No, that oxide would be brown not bright yellow.
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Eclectic
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Gadolinium?
My praseodymium ingot has a grey-green oxide coating.
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IrC
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Your Pr has to be kept under oil, and Vulture's explanation is exactly correct as to color. It helped me by eliminating my dilema as to what
would have been green, but was gone after I dried the oil off of it. Gd can sit on a table for years and do nothing. You have to get a CRC and merely
go through all the lanthanides, and take note of the color of every oxide. Then compare properties such as the fact that the metal I was sold as Eu
turns into a yellow powder rapidly in air. It is not really guessing, just comparing the listed properties of the element family in question. It is
unstable in air, and forms a yellow oxide. Only Ho and Ce form yellow oxides in the lanthanide series (in my CRC anyway), and only Ce is unstable in
air of the two. Not magic, just science.
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Eclectic
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My experience with cerium oxide as a glass and lapidary polishing compound makes me doubt that a bright yellow oxide would be cerium oxide. Usually
it's a pale salmon color due to other rare earth contamination, and I think that the purer grades tend toward white. Now where did I put my 8 lb
jar?
(Yea, the gadolinium idea was just a wild guess. I couldn't find a way to delete the post)
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IrC
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Glad you brought that up. I have a two pound container of cerium oxide for polishing, and it is also white, which led me astray for a while. To quote,
"Cerium oxide usually appears as a yellow powder" from this page: http://www.reade.com/Products/Oxides/cerium_oxide.html , as you can see this whole lanthanide thing can drive you nuts. I am amazed at the lack of
knowledge online about any of the elements in this series. I wasn't saying the other comments as a put down, I went through the same thoughts. I
was just using that as an example of what I was doing to figure this all out, namely looking through all the sources I could find and trying to come
up with the best answer. I am clueless why I have two pounds of cerium "snow white" oxide for polishing while all the references including
my CRC say yellow. I wish someone who knows more chemistry than me would come in here and clarify that one. It must be related to the plus 3 or plus
4? If so, which one is my white and which one is my yellow?
Dumbass me, I just read further in the link I just posted and the yellow is CeO2, so this yellow is plus 4? Therefore the white is Ce2O3 or plus 3?
[Edited on 20-8-2005 by IrC]
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IrC
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After finally hearing from the seller, this subject is getting even more confusing. In fact I am beginning to think science forgot that some of these
elements exist! From this link: http://www.reade.com/Products/Oxides/europium_oxide.html , quote "It appears as a pinkish white powder." Now go to my seller: http://www.elementsales.com/re_exp/index.htm . You can see clearly he got the same yellow powder, so maybe I really do have Eu2O3? My first chunk
I put in a beaker in the dead of winter (dry air), just a single layer of paper towel rubber banded tightly so no dirt or dust could get in but O2
could. It disintigrated into a rose white powder just as the reade link says. I never saw a yellow stage. This second piece only gave yellow (august,
humidity 58 percent), exactly as in the seller's test. He told me that after a long time the yellow faded into the rose white it now is. But if
so why would reade not mention a yellow stage, why did I get only white with no yellow the first time?
If this is Eu and not Ce, it explains why it did not burst into flames when I was breaking it up. I would not have tried cutting up Ce in air from
what I have read about it. I think I am going to give up chemistry and get a job selling burgers while I still have my sanity. (At least, I think I
do)
Does anyone think I am running in circles here? How can so many different factors be stated so differently by so many "reliable" sources on
the internet? Like was mentioned, polishing cerium oxide is white but many sources state yellow, this is what started me going off on a tangent
thinking my Eu was not Eu, yet if my yellow powder is Eu why do sources state it should be white? Is it possible some of what we read is written by
someone looking at a finished product in a bottle, and nothing is written by the people who actually make the stuff?
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Eclectic
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Exposed to air oxidation, you are getting lower oxidation states, mixed oxidation states, carbonates, hydroxides, oxides, maybe even nitrides.
It's wonderfully complicated. I'll read up on lanthanides in Cotton's "Advanced Inorganic Chemistry" and see if I can find a
bright yellow air oxidation product.
Has your yellow oxide changed color after further exposure to air?
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IrC
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No, it is so bright yellow I could probably paint it on the front of my car and drive at night with no headlights.
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Eclectic
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Sounds like uranyl nitrate  
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IrC
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My seller made some further comments on his experiments with lanthanides and I thought them interesting enough to add here:
"The lanthanides in general do strange things when they oxidize and their overall chemistry is strange and different than other metals. For the
chlorides the hydrated version can be very different colors than the anhydrous. The experiment I did started in February so the air was relatively
dry. humidity can play a big role in how these metal s corrode and possibly what compounds form when they do corrode.
For the europium compounds, heating them should drive off any hydrated water and decompose the hydroxide or carbonate to the oxide. I say
"should" because I've been stumped several times by trying to make compounds from the metals. I tried making the anhydrous chlorides
by heating the hydrated version of the chlorides (obtained with acid) and wound up with oxide and HCl instead of the chloride I expected."
I find that reading about reactions for most of the "ordinary" chemicals seems to be cut and dried (for the most part) i.e., most reactions
go forth every time just like they are written. However, for the lanthanides it seems very subtle changes in conditions cause big changes in outcome.
For example if I mix zinc and sulphur and light it up it always burns giving ZnS. But many reactions with the lanthanides can have very different
outcomes by nothing more than the humidity being in variance. I think this is part of why I love these elements so much, to me new territory is always
more fun to explore.
"Sounds like uranyl nitrate"
I wish I could get this so cheaply. I really got reamed on price buying this one, but at the time I could not find it anywhere else. What sucks is it
just sits around, I still don't have any mad science ideas for this chemical yet. So far my strangest experiment with actinides was by accident,
using hot melt glue to contain some and finding it dissolved in the glue making a chemical I have not seen before, the entire mass of clear glue while
molten absorbed completely a jet black compound making a real beautiful red plastic which of course is a good calibration source for my counters. I
have no idea what the chemical reaction was but it made a very interesting substance.
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sparkgap
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"...the entire mass of clear glue while molten absorbed completely a jet black compound making a real beautiful red plastic..."
Ooh, really cool.  Would it be possible for you to post a picture, if you have
one?
sparky (^_^)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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The_Davster
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I would be interested in seeing a picture of that as well. Who would have thought hot glue would be a solvent for uranyl nitrate!?
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praseodym
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IrC, have you found out the identity of the metal yet? I read this book that says that europium oxide is a pale powder, but you have described the
substance as bright yellow. Thats why I dont think the metal present is europium. Could you tell us more about the appearance of the metal? Because if
I am not wrong, cerium resembles iron in appearance.
By the way, other than uranium, what other lanthanides and actinides are radioactive and are able to undergo disintegration??
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Eclectic
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Promethium in the lanthanides. As far as I know, all of the actinides are radioactive.
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praseodym
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So can the metal that IrC has be an actinide? Because what I am thinking is that the confusion over the identity of the metal could be due to
disintegration/decay of the metal that causes a mixture of different metals as well as the change in properties of the metal. But I am not very sure
if this is possible, though.
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Eclectic
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If the element was decaying that fast, everyone within a city block would be dead from radiation exposure
This is just straight chemistry.
I only was joking about uranyl nitrate because it is the most blindingly fluoresent yellow inorganic compound I've ever seen.
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praseodym
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Like this?
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IrC
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My question is if praseodym's Location is in the Schwarzschild Radius how does he get any information out to us? Cool picture though. Many
lanthanides have natural radioactive isotopes as a normal percentage of their makeup. Funny, I have about all of them and I have never bothered to
check for activity, I need to do that. Promethium does not hang out much in this dimension, you won't find a source on this one. As to the
activity comment no doubt, that much activity would have vaporized me. Chemistry it is.
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