Sciencemadness Discussion Board

How do I make CsSeSc, any ideas!!

D4RR3N - 23-8-2007 at 06:40

I am trying to produce CsSeSc as I would like to conduct some tests on it. My knowledge of Chemistry is not very good, haven’t really studied it since College so hoping someone here has some bright ideas.

The most direct method of producing this would be to simply heat Cesium Selenide with Scandium metal powder in a vacuum. The cost I was quoted for Cesium Selenide however was very high so I’m going to have to find another method that is simple and not too dangerous.

Price quote for cesium Selenide Cs2Se:

> 1 g - 1935 EUR
> 10 g - 2576 EUR
> 25 g - 3184 EUR
> 100 g - 4966 EUR
> 500 g - 14679 EUR


Obviously I could fuse Selenium powder with Cesium metal to produce this but as you know Cesium is explosive and not too easy to get either!

Another method someone suggested to me was dissolving Selenium powder in Hydrazine and by slow addition of concentrated CsCl solution, you precipitate Caesium Selenide. I have never used Hydrazine but from what I have read its dangerous stuff! I would need to produce about 25g so guessing this method might not be suitable.

Now onto some ideas I have had but need some help with.

Cesium bicarbonate when heated decomposes into Cesium carbonate. If I were to heat Cesium carbonate with Selenium powder at a fairly high temperature would the Cesium fuse with the Selenium and give off Carbon trioxide?

CsHCO3 > heated > Cs2Co3 + Se = CsSe + CO3 ?????

My other Idea involves using Cesium Hydroxide?

If Cesium hydroxide was mixed with Selenium powder or Selenium dioxide what would be the result?

I also read that Scandium Oxide will dissolve in alkali to form Scandate salts. If I were to dissolve Scandium oxide in Cesium hydroxide what would be the resulting salt?


So any ideas guys?

[Edited on 23-8-2007 by D4RR3N]

Fleaker - 23-8-2007 at 08:51

How pure do you need it?

How pure do you want your starting materials to be?

I think 1935 EUROS (! ow) is a bit steep.

Look for my U2U


Edit: reading over your post, some of your reactions aren't going to work and can't be balanced right. In particular, the one with CO3 as a product. I don't see it happening, while the CsSe is slightly more plausible, I'd think it would be Cs2Se (which would make your equation balance).



[Edited on 23-8-2007 by Fleaker]

D4RR3N - 23-8-2007 at 10:35

Yes it is Cs2Se, and yep the price is shocking, but I guess they only make it to order.

The purity needs to be relatively good, so not looking for ultra pure, would be nice but.

12AX7 - 23-8-2007 at 10:38

Presumably, you want those 25g for stoichiometric reaction with Sc? That's at least 5g Sc, which will run you about as much. Seems reasonably priced, considering the end product.

Alternately; Sc2O3 is common (as scandium goes), and might be dissolved in acid (to give a solution of ScCl3 or Sc2(SO4)3), then reacted with a selenide (e.g., Na2Se) to precipitate Sc3Se2. Likewise, Cs2Se can be made in solution as well: 2CsOH + H2Se = 2H2O + Cs2Se, by bubbling H2Se gas through a strong solution of CsOH, which should be cheaper to come by. Evaporate and crystallize, then calcine to remove hydration (I'm guessing it will form a hydrated salt). Extra Se or H2Se may be necessary during the dehydration process. Alternately, the gas could be applied to molten CsOH or Cs2O, directly giving the anhydrous salt. I don't know what purification would consist of, but I would guess evaporation, distillation or sublimation. It will of course have to be carried out in a selenium- and alkali-resistant container; nickel might suffice, but I don't know how resisant to Se it is. Once you have these reactants, you are free to mix them in whatever proportions you desire on the Cs2Se-Sc3Se2 system.

Tim

D4RR3N - 23-8-2007 at 11:24

Thanks for your reply Fleaker and 12AX7!!

No that price was just for the Cs2Se, I think the price is outrageous...I would then have to purchase the Scandium and fuse it to form CsSeSc myself.

I would rather produce Cs2Se and then react it with the Scandium metal then produce Sc3Se2 and then react it with metallic Cesium.

If I heat Cesium carbide with selenium powder at high temperature will carbon trioxide be given off to leave behind Cs2Se ????

Chemicals I can obtain easily are:

Scandium metal
Scandium Oxide
Cesium bicarbonate
Selenium powder
Selenium dioxide

Was hoping I could do something with those substances?

woelen - 23-8-2007 at 11:37

CsSeSc? Does this really exist? I find this a very strange formula. Cs always is in oxidation state +1 and Sc in oxidation state +3. Then Se should be -4, which is impossible.

From your post I get the idea that you have to do some studies anyway. You are talking about carbon trioxide and cesium selenide from cesium carbide and selenium. First, cesium carbide is something very different from cesium carbonate. Second, carbon trioxide does not exist in macroscopic quantities under any known condition. Third, carbonates are rather inert and will not react, only at very high temperature it may decompose, leaving the cesium oxide behind.

I also want to give a word of warning here. Given my doubts on your chemical knowledge and experience, I think you should be VERY careful with selenium and its compounds. Selenium dioxide is VERY toxic, and selenium as element also is extremely dangerous, when strongly heated. You will really damage your health if you do not take very good measures for your own protection.

Finally, what is the goal of this experiment? I am wondering what application you have in mind for CsSeSc.

JustMe - 23-8-2007 at 11:39

Can you get iron filings? Hydrochloric (Muriatic) Acid?

Nasty way of getting there, but if you add iron filings to fused Selenium the resulting Ferrous Selenide can be reacted with Hydrochloric Acid to form Hydrogen Selenide. I believe that the H2Se can then be bubbled through CsOH or the Cesium Bicarbonate to produce Cesium Selenide. At least this is a route if you have excess of the reagents.

Please note the H2Se is 20x more toxic than HCN (cyanide).

D4RR3N - 23-8-2007 at 11:56

Yes woelen as I said in my first post, I haven't studied Chemistry for years so lets just say Im rusty lol

I know Selenium is toxic, I wasent thinking of heating it out in the open and breathing in any fumes. Was considering heating it in a vacuum furnace or sealed tube attached to a vacuum pump.

I am interested in testing the electrical properties of a compound that contains Cesium, Selenium and Scandium. Perhaps I am wrong about CeSeSc but the three elements should combine I feel????

Justme:

I can get hold of HCl but I dont like the idea of producing a deadly toxic gas!

From Wikipedia

"Scandium(III) oxide is a white amorphous powder used in high-temperature systems (for its resistance to heat and thermal shock), electronic ceramics, and glass composition (as a helper material).

It is converted into the Lewis acid scandium(III) triflate by reaction with triflic acid.

It is converted into scandium(III) chloride by reaction with excess aqueous HCl or aqueous HCl/NH4Cl mixtures.

Sc2O3 + 6 HCl → 2 ScCl3 + 3 H2O

Unlike its higher homologues yttrium oxide and lanthanum oxide, scandium oxide will dissolve in alkali to form scandate salts. In this, scandium shows more similarity with aluminium oxide"

Just wondering about the last statement "scandium oxide will dissolve in alkali to form scandate salts" What would be the result of Cesium hydroxide + Scandium Oxide?

Thanks for everyone's help!!

[Edited on 23-8-2007 by D4RR3N]

woelen - 23-8-2007 at 12:18

Cesium hydroxide and scandium oxide will give cesium scandate. The hydroxide ion reacts with the scandium oxide:

Sc2O3 + 6OH(-) --> 2ScO3(3-) + 3H2O (this is highly simplified, but it shows the main idea)

However, I doubt that you easily can isolate cesium scandate. This compound only exists at very high pH. At neutral solutions, you'll get an opposite reaction. Hydroxide is formed again and Sc(OH)3 will precipitate.

You might get cesium scandate if you fuse a mix of scandium oxide and cesium hydroxide. This, however, will require highly corrosion resistant material. Glass will be attacked quickly by molten CsOH.

Making CsOH from CsHCO3 also is not an easy task. You can easily make Cs2CO3 by heating, but making the hydroxide is another matter.

D4RR3N - 23-8-2007 at 13:20

Since some have doubts about the existence of CsSeSc let me ask a theoretical question, If I were to mix Ce2Se and Se powder in a sealed vacuum tube and heat it so that the two fuse what would be the result?


If I were to fuse Cesium hydroxide with Scandium oxide to produce Cesium scandate (assuming that this is possible) would it be an easy task to take the Cesium Scandate as a raw material and produce the theoretical CsSeSc?

not_important - 23-8-2007 at 16:53

There is a problem in that you are trying to form a compound that would be rather deficient in selenium - Cs wanting to be +1 and Sc +3 and ignoring any possible metal-metal bonds one would expect CsScSe2 or a mixture of Cs2Se and Sc2Se3

It is possible to displace oxygen from compounds with one of the other of the chalcogens, but not always and often only under rather extreme conditions. Generally you need an excess of the other chalcogen and must remove the chalcogen oxide from the reaction mix as a vapour; you'll have an excess of the chalcogen remaining in the mixture and may fail to remove all the oxygen.

An alternative to reacting an oxide with an elemental chalcogen is to heat the oxide in a stream of the chalcogen hydride
In2O3 + 3H2S => In2S3 + 3H2O
again with an excess of the hydride. Given that H2Se is rather toxic, more so that H2S or HCN, ill smelling, and not very stable, this is not a popular method.

As the chalcogen hydrides are weak acids, aqueous conditions favour the hydroxides unless the chalcogenides are rather insoluble. Cesium selenide is soluble, solutions of it are hydrolysed and easily oxidised by air.

Heating Cs2Se and metallic Sc in a vacuum would likely go thusly:
3Cs2Se + 2Sc => Sc2Se3 + 6Cs(g)

You may find the attached PDF on the making of cesium-bismuth selenides of interest.

Attachment: A2Bi8Se13.pdf (227kB)
This file has been downloaded 729 times

D4RR3N - 24-8-2007 at 07:19

If it is not a possibility to produce a compound from fuseing Cerium, Selenium and Scandium then there is another compound I am interested in, it also contains Scandium.

Ferrous Iodide (FeI2) + Scandium metal (Sc) or Scandium Iodide (ScI3) + Iron (Fe)

If these were to be fused would they form a compound??

not_important - 24-8-2007 at 07:44

Not by any references I have, you'd get metallic iron and ScI3 if in equal molar amounts. Enough scandium metal and you get Sc-Fe alloys plus ScI3, an excess of FeI2 will give iron and a mixture of the iodides.

It's not that a compound of Cs, Sc, and Se does not exist, I don't have full enough reference materials to write that off. But Cs and Sc are rather electropositive, such a compound would have to have at least enough selenium to to CsScSe32 I suspect.

Sauron - 24-8-2007 at 16:46

Sir, I suggest you proceed to Chemical Abstracts, and determine is ANY compound of Cs, Se and Sc has ever been prepared, if not, then I suggest you look for something else to do.

The vacuum oven and pump will do you no good unless you vent the pump into a fume hood. Preferably the oven and pump should be IN the fume hood.

Do you have a good fume hood?

D4RR3N - 25-8-2007 at 04:39

If something can't be found in literature it dose not mean that it cant be done necessarily, just means that others have not had a use for that compound.

I know how a vacuum pump works and realise that fumes/gas will exit the pump outlet port. I was intending to take an air line from the output port of the vacuum pump and fix an air stone (like you see in an aquarium) to the end. I would then place the end in to a long cylindrical container filled with a solution to remove the fumes. The output air line would be outside the building. The furnace would be opened when cool.

When you talk about a fume hood dose it suck the fumes out and expel it into the environment or dose it scrub/filter the output?

For my purposes I guess its not necessary for the elements to combine to form a singular compound, it still may have the desired properties as a mixed compound.

I would like to test the electrical properties of a material which containes Cesium, Selenium and Scandium. It may not form a pure compound but I guess thats not a requirement, would be nice though!

Likewise Is it not possible to produce a compound which contains Iron, Scandium and Iodine?? Problem with this is I dont think the furnace temp is high enough to melt this mixture.

Sauron - 25-8-2007 at 05:04

You can place a scrubber between the pump and the hood or you can install a scrubber on the entire output of the hood. Or you can do both.

Selenium is highly toxic and obnoxious.

Metallic cesium is not "explosive" but it oxidizes very readily and in a finely divided form is likely to be pyrophoric, which is probaby what you meant. In order to handle cesium you need a glove box with a totally inert atmosphere such as dry Argon. I suspect that Nitrogen probably combines with cesium to form the nitride. But I have not investigated the properties of cesium. Yoy will want to read Gmelin, Mellor, and so on. That is the primary literature of inorganic chemistry.

If a compound can'be be found in the cumulative literature indexes of the last 100+ years then it is HIGHLY SUGGESTIVE that that such a compound not only has never been made but that it may not be readily made and might be impossible to make.

My suggestion was to check C.A. for not merely your hypothetical CsSeSc but ANY compound of those three elements in ANY stoichiometry. Several knowledgeable chemists in this thread have questioned your compound's chemical logic, so what I am saying is that if NO combination of these three elements in ANY ratio is known to exist, then, just perhaps you are whistling in the dark.

We had a putz on here last week trying to peddle the notion that the compound Hg2Sb2O7 was not only real but has some very peculiar properties. So I for one am a little raw from that experience, and I would rather not hear about any more imaginary materials this year.

Can you tell us why you believe that your compound, or mixture, whatever, of Cs, Se, and Sc will have special electrical properties? And what those electrical properties might be?

Selenium is or was used in old fashioned rectifiers and also in obsolete light meters for its photoelectric properties.

Cesium, if my memory serves is used in photomultiplier tubes such as night vision devices. So Cs and Se both are optoelectronic materials.

I am familiar with some of the chemical uses for Sc in catalysts but not of its other technological applications.

Scientists are all skeptics and mostly from Missouri if you get my meaning.

sparkgap - 25-8-2007 at 05:24

Do satisfy my curiosity, kind sir, as to why in particular have you singled out cesium, selenium, and scandium to blend and then test. For that matter, also the other "composition" you speak of.

sparky (~_~)

Sauron - 25-8-2007 at 05:25

I found a thread you started on same subject in another chemistry forum on Google.

http://www.chemicalforums.com/index.php?topic=18706.msg71801

I also found a Springer link to an article about cesium selenide in the Russian journal ATOMIC ENERGY.

http://www.springerlink.com/content/n0w1882g432351kh/

What a coincidence.

As you probably already know, Cesium selenide has formula Cs2Se and exists as CsSeCs. You want to displace one Cs with Sc, however as you have already been told on this and another forum this will not work.

My suggestion stands. Go read the literature, I suggest you try Nuclear Science Abstracts (published by the US DOE) as well as C.A. Do not expect us to do your paper chase for you, and do not expect a forum for amateur scientists to have any information at our fingertips regarding high tech themionic emitter binaries for nuclear applications. That is apparently what you are after and that is way off our turf, my friend.

[Edited on 25-8-2007 by Sauron]

D4RR3N - 25-8-2007 at 05:40

Are we talking about a carbon filter type device, like used in a regular kitchen extractor unit?

I am grateful for all the input I have received and yes I agree there are some very knowledgeable people here.

I did not make the statement that such a compound will have special or unique electrical properties, nor will you hear me make such statements.

Like I said I would like to test the electrical properties of such a compound/ mixture.

Obviously I do have a technological application in mind but this compound only functions as a part and the whole thing would be very lengthy and complex to discuss so rather not go there, hope you guys understand.

I am not a Chemist so don't pretend to have a great deal of knowledge about chemical reactions etc

Would be grateful however if someone could explain to me why Iron, Scandium and Iodine also cant combine to form a compound?

D4RR3N - 25-8-2007 at 05:48

Sorry Sauron I was typing so missed your last post, you are jumping to conclusions about my application. I don't even know what "high tech themionic emitter binaries" are. My aplication has nothing to do with atomic energy!

Sauron - 25-8-2007 at 05:53

Be that as it may I am disinclined to assist you. Goodbye. The proprietor of this forum can decide whether your request is a suitable subject matter for a forum about amateur science. I am washing my hands of the entire topic.

By the way Alfa Aesar sells no Cs or its compounds, and no Sc or its compounds. And they are one of the largest specialists in inorganic chemicals.

sparkgap - 25-8-2007 at 05:57

"the whole thing would be very lengthy and complex to discuss"

Try us. ;) We'll need all the info we can get if we are to assist you.

"why Iron, Scandium and Iodine also cant combine to form a compound?"

Maybe. Maybe not. It however seems improbable. Please do a search in the relevant lit. (e.g. CA, which has been previously suggested).

sparky (~_~)

not_important - 25-8-2007 at 06:09

So after a bit of literature research it turns out that Sc does form cluster compounds such as Sc19Br28Z4, where Z is elements such as Mn, Fe, Os, Ru. I knew the lanthanides form similar compounds, including with Ni and Pt, but scandium is smaller and my own books didn't mention any such clusters - they're relatively new discoveries.

There are also scandium complexes with halides, that form compounds such as Cs3ScCl6. These are made by melting the halides together and waving instrumentation at the melt.

Also possible are cluster compounds of lanthanide halides with B, C, N, Si, and a few similar elements, scandium forms Sc6I11C2 and Sc4Cl6B among others. These cluster compounds can react to form more complex halides, such as Sc(Sc6Cl12N), K2LaZr6Cl18B, and La6I12Z where Z is a metal from within the box bounded by Mn, Re, Cu, and Au (silver doesn't seem to form such, though) and La is certain of the lanthanides.

The lanthanides proper also form some complex chalcogens, but Sc isn't mentioned and none include any of the alkali metals. They also seem to be limited to the f-block metals.

The complex cluster halides are made by melting together the LaX3 and other metal halide, along with the proper amount of Sc metal. Note that the ratio of lanthanide to other metal is several of the La to each Z, so some of the La halide is needed as well as the Z halide, you can't reach them from just the lanthanide metal and the Z halide.

So a bit of research may not turn up the exact compound you're thinking of, but it can find related ones that are useful guides to making what you seek, if possible. The previous PDF I included talks about similar compounds from Bi, the techniques used may be applicable. And this one may also be of interest.


[Edited on 25-8-2007 by not_important]

Attachment: Composition and temperature induced changes on the structure of molten ScCl3–CsCl mixtures.pdf (828kB)
This file has been downloaded 1521 times

D4RR3N - 25-8-2007 at 06:13

Sparkgap:

That would require me divulging classified information which you would require high security pass to access.......... just kidding:D

It is for a semiconductor application and If I go into the specific details it will void my patent.

Sorry Sauron that you feel that way.


I have been studying the literature the best I can.

[Edited on 25-8-2007 by D4RR3N]

D4RR3N - 25-8-2007 at 06:36

Thank you not-important!!!

So I guess you are telling me that it may be possible but nobody knows for sure:)

I guess the only way to know for sure would be to actually do it and analyse the formed compound.

not_important - 25-8-2007 at 06:41

The stoichiometric values you want simply do not appear to occur, there are compounds in the general class but the simple formula all give apparent bonding of arounbd 2, with metal-metal bonds taking up the slack, and nothing like that with A(I) metals.

There was a lot of research on these done in the `90s. In this decade it appears to have moved outside the US, appearing in journals less accessible to those in the US. I've found a number of reports in the field from researchers in China that may not show up in any English language indexes as of yet.

Attachment: 5611x1527.pdf (483kB)
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Sauron - 25-8-2007 at 06:43

FWIIW none of those three elements is a netalloid like As or Ge so a semiconductor is a wee bit dubious.

Cs and Se do have optoelectronic properties. As I said earlier. Sc does not.

If this is related to an invention I suggest you do not bandy it about on the Web any further. This thread is already on Google, you know. As is your thread on that other group forum.

Thermionic emitters are simply electron sources for CRTs, usually they are filaments like tungsten wire which can emit electrons when heated resistively. Don't ask me what the Russians or Georgians are up to with Cs2Se in this regard but I doubt it is picture tubes for television sets. Some sort of electron beam device, I guess, not necessarily a weapon but not necessarily NOT so. The Springer link is there if anyone wants to find out. Not my cup of cha. Neither is inorganic chemistry nor materials science. I am an organiker through and through and if it isn't made mostly of carbon, it makes my eyes glaze over.

not_important - 25-8-2007 at 08:06

You don't need a metalliod to have a semiconductor. Nickel oxide doped with lithium oxide is a semiconductor, for example. Many of the metal cluster compounds have metallic or semiconductive electrical properties, as do a number of purely organic compounds. Nitrogen doped diamond is a semiconductor.

Sauron - 25-8-2007 at 08:22

True but none of those are remotely like CsSeSc.

The thread author is I think being a little disingenuous, and he is certainly being coy about his application. That is his prerogative, of course, but it does nothing to reassure me that my alleged conclusion jumping is not spot on.

He does not appear to be equipped to prepare even Cs2Se (CsSeCs) without poisoning himself and his environs. He is pretty vague about what a hood might be and what a scrubber is and how it works.

I'm just dubious about the whole proposition and want nothing to do with it.

sparkgap - 25-8-2007 at 08:49

Gut feel is telling me that what he *really* needs is nothing like that mix he proposes. Or, worse still, someone's already found something that will do what he wants to do, only more cheaply and less complicated. ;)

sparky (~_~)

P.S. I still see no rationale for the selection of those particular three.

Sauron - 25-8-2007 at 09:01

Maybe one of should request that Russian journal article from References, because that is specifically about CsSeCs etc.

That ought to give you your rationale for something, with that sort of structure, but it won't be a semiconductor, methinks. Maybe someone should go further than I did with a Google search, and someone might actually dig in C.A. and Nuclear Science Abstracts.

I think all we are getting from this guy is misdirection, like a stage magician. We are being played for fools. Baffled with bullshit. He won't confide (well, this is no place for it, truely).

The_Davster - 27-8-2007 at 19:36

There is a software program that I have used before. It searches the literature for ternary compounds of metals and nonmetals. Your search would best start here.

Synthesis should be analagous to this
http://pubs.acs.org/cgi-bin/abstract.cgi/inocaj/1996/35/i18/...

Have fun finding the compounds which are formed! Usually many are, and x-ray crystalography is required to find which are in your sample.

[Edited on 27-8-2007 by The_Davster]

not_important - 28-8-2007 at 07:25

I knew some of the rare earth based chalcogenides had semiconductive properties. Here's the likely root of the question behind this thread.
Quote:
Mixed metal chalcogenides formed of lanthanide chalcogenides having the formula MLnX2 where M is selected from the group consisting of Ag, Cu and Au; Ln is one of the elements of the lanthanide family other than Pm and X is selected from the group consisting of S, Se and Te and having electrical properties that range from dielectrics to semiconductors to metallic conductors in a temperature range from -50° C. to in excess of +100° C. T


Note that it is as I suggested - MLnX2.

Attachment: US5458865A1.pdf (648kB)
This file has been downloaded 843 times

perry798 - 24-9-2011 at 13:40

Be VERY, VERY careful indeed when working with hydrogen selenide!!! I found out why - THE HARD WAY!!! By accident I exposed myself to a HIGH concentration of the gas. The first sign of danger was the change of odor from rotten radishes / 'gas' to STRONG ODOR OF ROTTEN EGGS. I stupidly ignored this warning. Suddenly without any further warning: my nose started STINGING / BURNING UNCONTROLLABLY - NO MATTER HOW QUICKLY I RUSHED TO THE NEAREST WINDOW. Still the UNBEARABLE STINGING / BURNING WOULD NOT GO AWAY, OR EVEN LESSON IN THE SLIGHTEST!!! SEVERAL hours later the stinging / burning in my nose was tolerable and had almost gone - only to be left with a nasty cold that took at least a few days to get over. I could have only been exposed to the gas for a few minutes at the most - while I was transferring some aluminum selenide from one container to another. By the way - always store and handle aluminium selenide away from even air!!