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Hydragyrum
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Black Phosphorus
Hi all,
I hope this is the right place to ask this - if not, apologies!
I am looking to acquire a small amount of phosphorus (black allotrope) just for an element collection - I don't need red or white for this, and I
believe the black allotrope is docile enough to have sent by post without problems.
My only problem is: where to find some? I've searched this forum, and also on ebay, with no luck so far. If anybody can point me in the right
direction, that would be fine.
I am in Australia, but I think black P will be OK to have sent from overseas... if I can find it.
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ScienceGeek
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Check out this website:
http://theodoregray.com/PeriodicTable/Elements/015/index.s7....
Ask this guy! He will certainly be able to point you in the right direction!
I also recommend taking some time on the website to check out his amazing elements- collection.
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Hydragyrum
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Thanks ScienceGeek, that seems like a good source of info - much appreciated!
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pantone159
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smart elements
Try this place - I have never ordered anything from them as their prices are very high, but they do have some interesting things, including black P.
(0.5 g 0.99998 P for 157 euros).
http://www.smart-elements.com/?
http://www.smart-elements.com/?element=P&arg=show&li...
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Hydragyrum
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pantone159, thanks very much for that link as well - it looks as though they have some nice things there - I'll check it out.
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Fleaker
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Yep, better get it while you can! It's not that easy to make and rather bothersome to recover the expensive reagent used in its synthesis (believe me,
I've done it  ).
I'm going to have another crack at it sometime soon though.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Saber
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Black P is rather expencive to buy.
One can make it however, simply use a the apparatus used to produce white P from red P. what is left after the 'distillation' of the red phosphorus is
black P. It can be seperated by dissolving the red and white P in chlorine water, leaving the black allotrope.
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Hydragyrum
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The link given by pantone159 sure does have some nice black phosphorus available - about which they say, "On behalf of a research laboratory we
offer these extremely rare crystals of pure black phosphorus, which were made by a new process. Black phosphorus can be prepared under low-pressure
conditions at 873 K from red phosphorus via the addition of small quantities of other elements."
Seems this 'new process' has been described in the literature - for any interested, please see: Inorganic Chemistry (2007) 46, 4028-35. The article
refers to a method for black P production at 873K. Interesting stuff, but €157 is probably too pricey for me 
Saber, you posted while I was writing - thanks for the info!
[Edited on 8-5-2009 by Hydragyrum]
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not_important
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Still a newer process, perhaps. The more traitional method, decades old, uses a seed of black phosphorus and some mercury as a catalyst, newer ones
use bismuth as a flux or just red phosphorus with temperature cycling under high vacuum.
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woelen
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Quote: Originally posted by Saber  | Black P is rather expencive to buy.
One can make it however, simply use a the apparatus used to produce white P from red P. what is left after the 'distillation' of the red phosphorus is
black P. It can be seperated by dissolving the red and white P in chlorine water, leaving the black allotrope. |
Are you sure this material is black phosphorus. I also did the experiment of making white P from red P and I also obtained some of the black material,
but only a very small amount. Total amount of phosphorus I used was 3 grams, and this yielded almost 3 grams of white P. The black remains are less
than 50 mg. I however, kept the black remains as well, just to be sure.
I considered this an impurity in the red phosphorus. I have read that making black P requires pressures of 12.000 atmosphere, which only can be
achieved in very well equipped labs.
[Edited on 9-5-09 by woelen]
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Eclectic
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http://www3.interscience.wiley.com/cgi-bin/summary/114035122...
http://dx.doi.org/10.1016/j.jssc.2008.03.008
http://pubs.acs.org/doi/pdf/10.1021/ic062192q
Could someone with full access make the articles available for us?
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woelen
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Interesting to read that there also are low-pressure techniques. Indeed, it would be nice if these articles could be made available to us.
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Fleaker
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Here are some articles
I have already attempted the black phosphorus synthesis on numerous occasions. I had a tougher time of it than I thought I would, mainly because I
rushed the heating profile and my pressure was 0.5 micron (needed to be lower in my opinion). My impatience there caused poor results.
Here are a few papers I have sitting on my computer from when I tried it. If anyone really wants to see it, I can go ahead and take the time to post a
bunch of photos of how I set up to do it. Unfortunately, I failed the synthesis. Now that I have very, very nice PIDs and muffle furnaces and a
proper vacuum system for 10^-7 torr, I will definitely be attempting the synthesis again. I just need a free weekend sometime!
I promised the black P synthesis just as well as the Cs and Rb synthesis (which in the case of Cs did work, however, I need to make a larger apparatus
from SS316 and quartz). I have 2 new clamshell tube furnaces which I hope to use in my scale up synthesis.
By the way, most likely Saber found Hittorf's phosphorus (violet phosphorus, which looks black finely ground). It could also just be carbon? In any
case, it isn't black phosphorus!
Attachment: Black P by gas phase transport.pdf (300kB)
This file has been downloaded 3260 times
Attachment: blackphosphorus.pdf (516kB)
This file has been downloaded 4963 times
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Hydragyrum
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Thanks for the articles Fleaker. Is that some kind of preprint you've found?
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Jdurg
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Thanks for the articles Fleaker. I passed the information along to a buddy of mine who has that whole apparatus and the funds/ability to conduct the
experiment. Hopefully he gets some good results.
\"A real fart is beefy, has a density greater than or equal to the air surrounding it, consists of the unmistakable scent of broccoli, and usually
requires wiping afterwards.\"
http://maddox.xmission.com. |
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Fleaker
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Well if he doesn't have oxy hydrogen, then he won't have success. Similarly, if he doesn't have ultra high purity red phosphorus, he will also fail.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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careysub
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Here is the paper on preparing black phosphorus using metal catalysts. It is mentioned above, but the paper is not provided.
It is pretty neat. It uses a significant amount of gold (recoverable probably), about $3 worth for 150 mg of P, and requires the use of silica
(quartz) ampoules since the transformation temperature is ~900 C.
It would be nice if you could get a screw-seal refractory metal vessel for this, so making and breaking quartz ampoules is not required.
Attachment: lange2007.pdf (339kB)
This file has been downloaded 661 times
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Fleaker
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I think the gold would wet the refractory metal. Molybdenum handles iodine well (indeed, in van arkel de boer apparatus for crystal bar production,
it's usually moly-clad inconel 625--spendy!).
I would like to get this done again now that I have some larger roughing pumps and a turbo pump as well as a large programmable box oven.
The ampoules aren't hard to make if you work in narrow diameters and with a Hoke torch. It is blinding work with quartz, but aside from the heat, it's
more forgiving than borosilicate.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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careysub
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Gold does not wet molybdenum or tungsten unless special preparation is made to do so.
The normal oxide layer prevents wetting so either it must be removed in a reducing atmosphere or a special gold-platinum alloy is required for wetting
to occur.
If necessary an oxidation preparation step might be called for (but from what I am reading, not). If the gold is introduced as a nano-powder
(precipitated gold) thoroughly mixed any possibility of wetting is probably minimized.
Although ready-made molybdenum parts (threaded tube and end caps) do not seem to exist, molybdenum tube and rod is readily available and is apparently
easily worked by common machine tools. Cutting an internal thread in the ends of a tube, and an external one on a rod of matching diameter (perhaps
with a little milling to size) would create such a reaction vessel easily enough. Just a matter of some dollars. Expensive no doubt, but not, I think,
extravagantly so, since all the materials and methods are readily available commercially
[Edited on 27-6-2016 by careysub]
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Fleaker
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I'm presuming reducing conditions of P vapor prevail in the tube, although whether or not that affects the W or Mo layer remains to be seen. Having
run several hundred kilograms of W evaporation coils + boats with gold on them, I can tell you this much, it sure as hell does wet tungsten in vacuum
conditions (as is pieces, not H2 reduced), though that might be due to sublimation of the WO3 when in use for PVD.
As an FYI, we routinely de-braze a pretty diverse array of materials (including PtAu brazed materials).
I have a great idea--why don't you test it out. I've already attempted the synthesis in quartz and had some issues with getting the ampoules sealed
with CH4/O2 and no issues with H2/O2; I'd be keen to see how it goes for you in an all molybdenum setup! Maybe Juergen can buy the black phosphorus
off you this time...
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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careysub
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It will be awhile before I get to that on my projects list - it is pretty long at this point (lots of stuff to do in my - eventual - retirement!)
If anyone has any other ideas about a possible container for this reaction. Although the temperatures aren't too extreme really, 650 C, a container
that can be hermetically sealed and won't react with at least one of the components is a problem, e.g., anything containing nickel (often used for
chemical resistance) seems out of the question since that is used as a gold scavenger.
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Fleaker
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I think fused silica tubing is still the cheapest option...
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Dan Vizine
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Making Black Phosphorus
Black phosphorus, the least reactive, densest and only known semi-metallic allotrope of phosphorus has a limited range of known synthetic methods:
1) synthesis under high-pressure conditions
2) preparation using mercury as a catalyst
3) the bismuth-flux based method.
4) a temperature/ high vacuum cycling process
5) Au3SnP7 method
6) Sn/SnI4 method
1) The synthesis of black P can be traced back to 100 y ago. In 1914 Bridgman first reported a method to convert white P to black P at a moderate
temperature of 200 °C and a high pressure of 1.2 GPa within 5–30 min. By melting black P at a temperature of 900 °C and under a pressure of 1 GPa,
black P single crystals larger than 5 × 5 × 10 mm3 can be achieved, as reported by Endo S, Akahama Y, Terada S, Narita S (1982) Growth of large
single crystals of black phosphorus under high pressure. Jpn J Appl Phys 21(Part 2, No 8):L482–L484. whereas recently it was reported that
amorphous red P could be transformed into crystalline black P at 7.5 ± 0.5 GPa even at room temperature.
2) A mixture of 50 g. of distilled, white P and 50 g. of Hg is placed in an ampoule filled with pieces of copper-plated welding rods. At the same
time, 0.5 g. of black P, which has been well pulverized beforehand in an atmosphere of N2, is added as seed crystals. The ampoule is fused shut and
gently heated until the white P melts. It is then shaken to achieve good mixing. As a result, a layer of seed crystal powder adheres to the newly
amalgamated surface of the welding rods. The ampoule is heated in a protective iron tube to 220°C and then, over a period of two days, to 370°C.
After a total of eight days, black P forms quantitatively. Its surface sometimes shows traces of white and red phosphorus.
To produce the seed crystals, a small ampoule filled with freshly distilled white P and 30-40 at. % Hg is placed in a furnace preheated to about 370
C. It is left there for three days at this temperature. It is then heated for one day at 380°C, one day at 390 C and three to four days at 410°C.
The well-formed spherules of black P can be easily separated from the other material.To extract the crude product from the admixed Hg, the pulverized
sample is placed next to a piece or Pb and heated in an evacuated ampoule for several days at 300-450 C. After repeating the process with the
re-pulverized sample and fresh Pb, the remaining Hg amounts to about 1 at. %. If gold is used instead of Pb in the second amalgamation the amount of
Hg after heating to between 370°C and 440°C is reduced to about 0.5 at. %. The Hg content cannot be further reduced by this or any other known
method. The crystals are reported to become wet over a period of days or weeks
3) Black phosphorus single crystals were prepared from a solution of white phosphorus in liquid bismuth.The bismuth is dissolved away with (1:1) HNO3.
Brown A, Rundqvist S (1965) Refinement of the crystal structure of black phosphorus. Acta Crystallogr 19(4):684–685. See also: Synthesis and some
properties of black phosphorus single crystals Y. Maruyama, S. Suzuki K. Kobayashi, S. Tanuma
4) Black phosphorus can be made from red phosphorus by thermally cycling red phosphorus in a vacuum between 360-400° C. and 200-240° C., whereupon
the red phosphorous undergoes an allotropic phase change to black phosphorus. A mere part of the procedure is enough to place it out of reach of
reasonable home synthesis. The detailed structure of the apparatus is therefore omitted.
The conversion process of the invention proceeds as follows: The container is charged with amorphous red phosphorus. The charge may be any size and
may be a single piece or multiple pieces. The vacuum chamber is then evacuated to a very low pressure, e.g. <1×10-7 Torr, and preferably
<1×10-8 Torr. The vacuum is conveniently pulled through exhaust valve in a third chamber. Before initiating thermal cycling it is generally
beneficial to purge the apparatus by outgassing the chambers and evaporating volatile impurities from the phosphorus source material. This procedure
involves heating to stages 1 and 2 to a temperature above 200° C., e.g. 250° C. or above.The P chamber is heated to a temperature of approximately
200° C., or above, to prevent material being outgassed from condensing on the walls of the vacuum chamber. Heating for several hours is adequate to
clean the apparatus. The valve is closed and thermal cycling initiated. Thermal cycling involves heating the red phosphorus container to a temperature
above 350° C., and preferably in the range 360-400° C., with a ramp of preferably 5-20° C./min. The red phosphorus is allowed to cool to a
temperature below 300° C., and preferably below 250° C., e.g. 200-240° C. The cooling rate may be comparable to, or more rapid than, the heating
rate. This completes one cycle. The red phosphorus is thermally cycled in this manner for three cycles or more, at which point the phosphorus
undergoes a sharp allotropic phase change from red to black. The change typically occurs after 3-5 cycles but may occur later. During thermal cycling
in a vacuum, P4 vapor is constantly emitted from the red phosphorus charge. This vapor is potentially hazardous. As the P4 vapor rises through the
second stage it is converted to P2, the less hazardous form. The third stage is provided to condense vapor that is unconverted in the second stage.
During the cool phase of the cycle, this vapor passes to the third stage where it is condensed. Material condensed in the condenser is potentially
hazardous and can be periodically burned, or the condenser can be removed and cleaned. The allotropic phase change from red phosphorus to black is
accompanied by a dramatic decline in the amount of P4 vapor emitted from the charge. The amount (grams) of white phosphorus condensed from the P4
vapor emitted by a 78 gram red phosphorus source is plotted vs. the number of thermal cycles. A drop in condensed white phosphorus after 4 cycles
signals the phase change of the bulk of the charge from red to black. The emitted P4 vapor can be monitored by a pressure gauge. This phase change is
stable and irreversible under the conditions of the process.
5) Black phosphorus can be prepared under low-pressure conditions at 600 C from red phosphorus via the addition of small quantities of gold, tin, and
tin(IV) iodide. Au3SnP7, AuSn, and Sn4P3 were observed as additional phases. Tin(IV) iodide remains unreacted during the preparation process. SnI4 was
prepared by mixing tin (12 g, 0.10 mol) and iodine (40 g, 0.16 mol) in toluene (250 mL). The mixture was refluxed for 30 min until the violet color
of the iodine disappeared. The hot solution was decanted from the remaining tin. Orange SnI4 crystallized after the mixture was cooled to room
temperature. The crude product was recrystallized from toluene and dried over molecular sieves. Black phosphorus was prepared by the reaction of gold
(70.5 mg, 0.358 mmol, 99.9%, foil, Chempur), tin (42.5 mg, 0.358 mmol, 99.999%, ingots, Heraeus), red phosphorus (155.2 mg, 5.011 mmol, 99.999+ %,
pieces, Chempur), and SnI4 (10.0 mg, 0.016 mmol, recrystallized) in evacuated (10-3 mbar) silica ampules (length 50 mm, inner diameter 8 mm). The
starting materials were heated to 550, 600, or 650 C and kept at this temperature for 5-10 days. Side products, grown on top of the bulk material
consisting of either Au3SnP7 and Sn4P3 (600 C) or of Au3SnP7 and AuSn (650 C), can be separated mechanically.
5 Alternate) The mineralizer SnI4 was prepared from tin powder (1.2 g, 99.995%, Chempur) and iodine (4.0 g, resublimed, 99.999%, Chempur) in 25 ml
toluene. The starting materials were refluxed for approximately 30 m until the violet color of the dissolved iodine disappeared. After decanting the
hot solution from the remaining tin the orange crude product was crystallized at room temperature. The crude product was finally recrystallized from
toluene and dried over molecular sieve. AuSn was prepared in a sealed evacuated silica ampoule using an equimolar mixture of gold (Heraeus, 499.9%)
and tin (Heraeus, 99.999%). A H2/O2 burner was used to melt the starting materials. After homogenization of the product the purity of AuSn was checked
by X-ray powder diffraction and the phase-pure starting material was used without further purification. AuSn acts as a binary precursor to accelerate
the reaction to the polyphosphide Au3SnP7 at elevated temperatures prior to the transport reaction. Red phosphorus (500 mg, electronic grade,
99.999+%, Chempur) and AuSn (364 mg) were transferred to a silica ampoule of 10 cm length and an inner diameter of 10 mm. Ten milligram of SnI4 was
added and the ampoule was evacuated to pressures lower than 10-3 mbar. The sealed ampoule was transferred to a muffle furnace and was placed
horizontally in the middle of the furnace chamber. After heating to 673 K within 1 h the temperature was held at that temperature for 2 h. In the
following the temperature was raised to 873 K (1 h) and kept constant at this temperature for 23 h. In a next step the temperature was reduced to 773
K applying a cooling rate of 40 C/h and kept at that temperature before the oven was switched off. The ampoule was cooled down to room temperature
within 4 h. This procedure results in the formation of black phosphorus with crystal sizes larger than 1 cm. The efficiency of the preparation process
can be substantiated by a reduction of the total reaction time and the amount of AuSn to 10 h (holding time at 700 C) and 200 mg, which results in
a comparable conversion ratio with slightly smaller (approx. 0.5 cm) black phosphorus crystals. A total conversion of the red to black phosphorus
can be achieved by a prolongation of the reaction time to 70 h at 650 C.
6) Black phosphorus can be made using Sn/SnI4 without Au. Red phosphorus (0.5 g), tin (10 mg), and tin iodide (15 mg) were loaded into a partially
sealed quartz tube in a glovebox. The tube was 14 cm long, with a 1 cm inner diameter and a 1.4 cm outer diameter. The tube and its contents were
evacuated to ca. 4 x 10-3 mbar and sealed with an oxyhydrogen torch while maintaining vacuum within the ampule.We ensured that the ends of the quartz
tubes were >0.4 cm and without entrapped gas bubbles; in one experiment, the quartz tube burst because the walls were too thin. (Caution: only
perform this synthesis in a well-ventilated area with restricted access as the risk of unanticipated explosions is high because the tube pressure
greatly exceeds 1 atm.) The reaction was carried out in a Lindberg Blue three-zone furnace using the temperature profile described by Nilges. We
maintained a 60 C temperature differential across the 15 cm tube by inserting insulation between the two zones.
With the increase of temperature a reduction of the crystal sizes was observed compared with the reaction at 600 C. It was shown that phosphorus in
form of P4 and P2 fragments is the only transport relevant species out of all starting materials and possible gas-phase molecule in the present case.
The very fast growth of black phosphorus within 32.5 h and a small temperature gradient to crystals larger than 1 cm can only be explained by a rapid
gas-phase reaction from these phosphorus fragments (mainly P4 and P2) at the reaction temperature.
No other possible transport species like tin iodides, gold iodides, iodine itself, phosphorus iodides or tin phosphides show reasonable transport
efficiencies at the applied temperature. We have determined the temperature gradient within the ampoule from measurements with an external
thermocouple close to the top and the middle of the ampoules and found a gradient of about 45 K at 600 and at 500 K. The exact application of the
reported temperature program is important to grow black phosphorus in the presented way. A deviation from the program led to the formation of white or
violet phosphorus as the main phase beside only small or no amounts of black phosphorus. Obviously the combination of different minority gas phase
species, the majority phosphorus components and some very complex and temperature dependent gas-phase equilibriums are responsible for the fast
formation of black phosphorus. More detailed studies of these phenomena are currently underway to achieve a full understanding of the growth mechanism
of black phosphorus.
The reported transport reaction led to the formation of large black phosphorus crystals within reasonable short reaction times. It represents a
significant improvement in preparation time and achievable crystal size compared with traditional methods like mercury catalysis, high-pressure
synthesis and bismuth-flux methods. The present method also drastically improves the previously reported low-pressure route to black phosphorus in
the overall product amount per reaction and maybe is suitable to bring the compound a little bit more into the focus of materials scientists
for electrochemical applications. Now a defined crystalline product is available at very high purity with no additional workup steps necessary, prior
to use. Up-scaling to higher product amount is only dependent on the size of the ampoule and furnace. A reduction of the amount of the starting
material AuSn and the mineralizer SnI4 is also possible in order to minimize the production costs and to optimize the conversion rate.
Given the parameters, method 6 is the only practical home synthesis of black P. Unless you have Au to spare, in which case method 5 is equally
practical. I think I'll try this synthesis next. Again, this won't be done in a short time, some basic skills need investigation. Sealing the quartz
tubing will need examination/practice.
Attribution for information in 6) will follow. A special thanks goes to Anginelle, should she ever happen to read this.
[Edited on 17-8-2016 by Dan Vizine]
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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Oscilllator
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Sealing the tube in a vacuum sounds extremely difficult. Have you considered doing something like flushing the inside of the tube with (for example)
highly pure CO2, and placing a small amount of Lithium oxide in the tube to absorb this CO2, leaving behind a vacuum?
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j_sum1
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What a great bit of research. Thanks.
Synthesising thorium aint enough for you Dan?
All of this looks well out of my league. Which of the methods do you think you will go for?
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