Sciencemadness Discussion Board - strontium aluminate

strontium aluminate

Jor - 18-3-2008 at 04:26

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?

Nicodem - 18-3-2008 at 04:38

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).

woelen - 18-3-2008 at 05:06

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.

Nicodem - 18-3-2008 at 10:36

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. Besides SrAl2O4 itself is has no luminescence properties, only doped SrAl2O4 show luminescence.
A quick search turned out the attached paper where SrAl2O4 type phosphors are prepared by calcination of SrCO3 and Al2O3 with boric acid as flux and Eu2O3 or Dy2O3 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 1585 times

Nicodem - 18-3-2008 at 11:14

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

vulture - 18-3-2008 at 14:19

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.

chloric1 - 19-3-2008 at 05:04

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.

Neil - 15-4-2008 at 08:34

http://www.freepatentsonline.com/EP0286180.html

Patent on making strontium aluminate with a flux

JohnWW - 15-4-2008 at 15:54

Quote:

Originally posted by Neil
http://www.freepatentsonline.com/EP0286180.html
Patent on making strontium aluminate with a flux

The plain HTML text can be read, but the PDF version cannot be viewed.

IrC - 16-4-2008 at 18:07

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

IrC - 16-4-2008 at 18:20

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

Nicodem - 17-4-2008 at 10:56

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]

IrC - 17-4-2008 at 18:56

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.

Vogelzang - 27-4-2008 at 11:24

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?

The_Davster - 27-4-2008 at 12:18

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.

Vogelzang - 27-4-2008 at 16:38

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]

not_important - 27-4-2008 at 19:56

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.

The_Davster - 7-5-2008 at 21:40

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]