Jor
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strontium aluminate
This substance is very interesting for phosphorescense.
It should not be to hard to make it. If it is not soluble, one would add a strontium nitrate solution to an alkaline aluminium solution, obtained by
dissolving aluminium in a hydroxide, and it should precipate out.
However I don't know if it is soluble. No data at all I can find. If it is soluble I was thinking the best way to obtain it would be adding an excess
aluminium to a hydroxide solution, such that hardly any free hydroxide is left in solution. Then add a strontium nitrate or chloride solution, and
freeze the solution to obtain the crystals.
I have no idea really whats the most effective way of preparing this substance. You should all wonder : 'dude, try it yourself?'. Well I am helping a
school student making this substance. I do not have strontium salts myself.
Ideas?
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Nicodem
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I would guess it is prepared by calcinating Al2O3 with SrCO3, but you should check at the library. If it is done industrially or has uses then check
also the patents. Preparing it by wet chemistry could be an option, but you will probably have to calcinate it anyway to get the correct
polycrystalline material (though probably at much lower temperature).
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woelen
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Making a solution of an aluminate from NaOH and Al is not feasible. The reaction will slow down and practically come to a halt, long before all
hydroxide is gone. A better option to my opinion is to use sodium hydroxide and aluminium chloride hexahydrate. Carefully add sodium hydroxide to the
solution of aluminium chloride. This gives a precipiate. Now slowly keep on adding sodium hydroxide dropwise, while constantly stirring and keep doing
this, until all precipitate just dissolves again. Now, add a slight amount of aluminium chloride again, such that the solution just is cloudy. Now you
have a solution of aluminate with hardly any hydroxide and you have some aluminium aluminate (a.k.a. hydrous aluminium hydroxide) suspended in the
liquid. Let the precipitate settle at the bottom and the clear liquid above it is your solution with aluminate. It also contains chloride, but that
should not hurt.
Now you can add your solution of barium chloride or barium nitrate to this solution. Whether this results in precipitation of Ba(AlO2)2.xH2O I do not
know, but I do expect it.
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Nicodem
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I don't see any advantage in using wet chemistry. Even if you get Sr[Al(OH)<sub>4</sub>
]<sub>2</sub>*nH<sub>2</sub>O to precipitate, you still need to calcinate it in order to get polycrystalline
SrAl<sub>2</sub>O<sub>4</sub>. Besides SrAl<sub>2</sub>O<sub>4</sub> itself is has no luminescence
properties, only doped SrAl<sub>2</sub>O<sub>4</sub> show luminescence.
A quick search turned out the attached paper where SrAl<sub>2</sub>O<sub>4</sub> type phosphors are prepared by calcination of
SrCO<sub>3</sub> and Al<sub>2</sub>O<sub>3</sub> with boric acid as flux and
Eu<sub>2</sub>O<sub>3</sub> or Dy<sub>2</sub>O<sub>3</sub> as dopants. The calcinations of the finely
powdered starting materials is done at 1300°C. So you need a tube furnace and a ball mill. (There are also references to other papers therein.)
Interestingly, I also found numerous internet vendors selling strontium aluminate powders with different luminescence colors. Looks like it is quite
popular among artists and the like.
Attached:
Tuning of emission colours in strontium aluminate long persisting phosphor
D Haranath et al
J. Phys. D: Appl. Phys. 36 (2003) 2244-2248. DOI: 10.1088/0022-3727/36/18/012
[Edited on 18/3/2008 by Nicodem]
Attachment: Tuning of emission colours in strontium aluminate long persisting phosphor.pdf (373kB)
This file has been downloaded 1584 times
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Nicodem
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Here is another paper with a more detailed experimental:
| Quote: |
Strontium aluminates were prepared from alpha-Al2O3 (purity 99.99%), SrCO3 (99.9%), Eu2O3 (99.9%), Dy2O3 (99.9%) and H3BO3 (99.99%) powders. These
powders were weighed in each case of strontium aluminates, and the samples were each doped with 0.68 mol% Eu2O3 and 0.27 mol% Dy2O3. They were
mixedand sinteredat 1300°C for 4 h in a reduction atmosphere (Ar+5% H2), and the products were ground. |
(For the stoichometry of various compositions see the full text.)
Attached:
Influence of Eu, Dy co-doped strontium aluminate composition on mechanoluminescence intensity
Morito Akiyama, Chao-Nan Xu, Yun Liu, Kazuhiro Nonaka and Tadahiko Watanabe
Journal of Luminescence, 97 (2002) 13-18. DOI: 10.1016/S0022-2313(01)00419-7
[Edited on 18/3/2008 by Nicodem]
Attachment: Influence of Eu, Dy co-doped strontium aluminate composition on mechanoluminescence intensity.pdf (131kB)
This file has been downloaded 1628 times
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vulture
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| Quote: |
I don't see any advantage in using wet chemistry. Even if you get Sr[Al(OH)4 ]2*nH2O to precipitate, you still need to calcinate it in order to get
polycrystalline SrAl2O4. |
Wet chemistry has the advantage of mixing your compounds at the molecular scale, something which can never be done with physical methods. This will
drastically reduce calcination times and temperatures. Look up sol gel methods for making ZnO for example.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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chloric1
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Yeh I agree with vulture here. Take aluminum nitrate and strontium nitrate in solution add europium nitrate in small amounts and crystallize. Then
heat. Or one might try heating the concentrated solution with urea solution until all water evaporate and conflagrant ignition sets in. This way the
mixture could heat from the inside outward.
Fellow molecular manipulator
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Neil
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http://www.freepatentsonline.com/EP0286180.html
Patent on making strontium aluminate with a flux
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JohnWW
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The plain HTML text can be read, but the PDF version cannot
be viewed.
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IrC
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Use this page:
http://www.freepatentsonline.com/EP0286180B1.html
or
http://www.freepatentsonline.com/EP0286180A1.html
Images are available in PDF form when logged in. (free)
Just create free account. I have both PDF's they show under search for the number given, trying to use attachment here. Hopefully they will both show
up when I post this? Never mind, cannot see how to attach both, so will make a second post.
[Edited on 4-16-2008 by IrC]
Attachment: EP0286180B1.pdf (209kB)
This file has been downloaded 657 times
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IrC
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Next one.
Forgot to add but long ago we all talked about this, try searching the site? I spent much money and time making glow powders and even bought a kiln
for this work. Nothing I have found beats doing solution work first then firing up the kiln! Trust me on this one. You will never activate good glow
powders without investing in a kiln and it is likely next to impossible to get the product mixed well enough for even crappy to no results dry!
You should be making your aluminates from solutions, then working with the kiln method, especially for exotic doping experiments. This subject is why
I actually own several pounds each of various lanthanides. And a kiln of course.
Nope, none for sale, I love this aluminate and lanthanide chemistry.
[Edited on 4-16-2008 by IrC]
Attachment: EP0286180A1.pdf (225kB)
This file has been downloaded 648 times
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Nicodem
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What kind of homogenization did you use? Have you tried a planetary mill or just the classical mortar and pestle in acetone slurry?
Often when you can not get a good reaction and the resulting polycrystalline material is contaminated with starting material, you can just powder it
back after the initial calcination, mill it and calcinate again (nothing new I guess).
I was also wandering if you can sinter the resulting strontium aluminates without them losing their phosphorescent properties?
PS: Off topic, but this patent, like almost all patents, is available for download as PDF for free and without any registration: EP0286180
It is just a matter of which interface/patent office you chose for the access.
[Edited on 17/4/2008 by Nicodem]
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IrC
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I bought a ball mill from United Nuclear, and 3 different drums, each with it's own materials depending upon what I am doing, metal or ceramic. As to
the ceramic grinders, these look like ceramic cylinders rather than balls. For ultra pure work you cannot make something different unless you are
using new grinding medium (and clean the drum very well). This is extremely important in light of unwanted impurities ruining the proper doping you
are going for. I might add virtually all of the chemical solution work I do as far as aluminates goes is based on calcium rather than sodium. I bought
a few pounds of calcium metal, in kind of a small balls shape, very similar to the Be metal I bought. Not sure what production method is the reason
many of these lighter metals seem to be easier to find in the shape of BB's to marbles? My guess was molten metal dropping into some form of cooling
liquid, but most don't have tails which I would expect?
The mills they make at United Nuclear are very nice, and not too noisy. I do solution work making various aluminates mostly, whereas much of the
actual mixing of various components is done using my ball mill. Acetone is a good mixing component which you can use inside the ball mill with ceramic
grinding media but I often wonder if I need to worry about static igniting things. I bought boron metal and various salts playing around with fluxes
and so on. The boron metal was for experimenting with making salts I cannot find easily. Actually many metals I buy are for experimenting with making
chemicals I do not see around much. Strontium nitrate I use for the nitrogen mostly. Really I spend a lot of time looking at other patents, and then
trying them while keeping in mind what new thing can I do along these lines.
I bought quartz sleeves which are 3 feet long and around 2 1/2 inches in diameter. These I can put through holes I made through the stainless outer
shell and the firebricks in my kiln, so I can put material inside the sleeves, run gasses through the tubes while the kiln is up to temperature. Kind
of like a combo kiln or tube furnace on demand, with refractory plugs for the kiln when the tubes are not being used. One trick I learned started when
I found a hundred alumina boats at a good price. I built a stand which holds the boat up a few inches above a metal plate, which itself is on feet off
the desk (for temperature protection of the desk). I make a new mix, and put some in the boat. Then I can blast it with a O2/Mapp gas or O2/Acetylene
and get a trial idea of what kind of glow if any will I see when I do the whole firing up the kiln routine. It takes practice to heat the mix without
blowing it out of the boat until it will stay in there even in the full force of the flame, while at the same time playing around with using oxidizing
or reducing portions of the flame depending upon what you are trying at the time. With practice it is a trick which works very well, and gives you a
quick and dirty first look at things like what color glow will this new doping produce, and so on.
Back to Vulture's point. I do not want to talk much about this other than to state he is dead on here. This is where I am doing a lot of
experimenting, with chemically making compounds which I then fire in the kiln, and Sol Gel methods are a line I play around a lot with, but do not
want to put into the public domain many of my ideas and results. As a further thought for any playing around with zinc glow powders, Ag activation for
the zinc glow powders is needed for scintillation screen experiments. Also you must try silicate chemistry as it relates to zinc glow powders. I have
also played around with using Silicates in many of my lanthanide doping experiments.
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Vogelzang
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Guten Tag, alle zusammen. Does anyone here know if you can mix a thorium salt such as thorium nitrate with luminescent strontium aluminate to get a
practical radioluminescent light source?
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The_Davster
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I do not know how well it could be incorporated in the way that you mention, as it would simply be a mix of thorium nitrate and the strontium
aluminate, and they could easily be separated.
However if one was to use a mix of strontium nitrate and thorium nitrate as the precursors along with an aluminum precursor in a sol-gel type
synthesis of the aluminate, it would bind up the thorium producing a more homogeneous product.
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Vogelzang
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They used to use radium and zinc sulfide in watch dials. Tritium is used more recently in radioluminescent light sources, but lasts only about 10 or
20 years.
http://en.wikipedia.org/wiki/Self-powered_lighting
http://www.orau.org/ptp/collection/radioluminescent/radiolum...
You can get strontium aluminate on Ebay.
[Edited on 27-4-2008 by Vogelzang]
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not_important
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| Quote: | Originally posted by Vogelzang
Guten Tag, alle zusammen. Does anyone here know if you can mix a thorium salt such as thorium nitrate with luminescent strontium aluminate to get a
practical radioluminescent light source? |
If the aluminate had an open structure, you could soak it in a solution of thorium nitrate, then dry and ignite to for ThO2. You would get increased
homogeneity with the sol-gel method.
However thorium has a long half life and isn't that radioactive, it may not cause enough excitation to generate much light.
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The_Davster
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I prepared some europium (and dysprosium ) doped strontium aluminate. Masses used corresponded to SrAl2O4, which in the literature has the highest
luminosity. Sol-gel methodology was used by adding a mix of strontium nitrate, europium nitrate, and dysprosium nitrate(rare earth content ~1molar
percent that of Sr) added dropwise(2h) to a stirred hot liquid aluminum tri-secbutoxide at 70C. After addition 0.8mL of conc. HCl was added dropwise
and the temperature was allowed to increase to around 100C and it was kept at this temperature until gel formation began to occur(3h). At this point
it was placed in my oven at 120C and allowed to dry to a powder(xerogel). This powder exhibits no phosphorescence, as I have not yet calcined at
>1100C under reducing hydrogen atmosphere, which is necessary to convert Eu3+ to Eu2+ which fits into the aluminate crystal structure's holes
introducing phosphorescent properties.
[Edited on 7-5-2008 by The_Davster]
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