Osmium monocrystal. Precious metal - osmium

Neither scientists nor officials can speak. Although, as it turned out, anyone can buy this isotope. On some Internet sites, the Kazakh isotope osmium-187 is sold in kilograms!

Passions raise the price

One gram of isotope-187, according to the Guinness Book of Records, costs 200 thousand dollars. But on Wikipedia our state is called the first and only exporter of pure osmium-187, which is offered at a price of 10 thousand dollars per gram.

By the way, such a range of prices and sensational presentation of information aroused serious passions around this rare metal. For Kazakhstan, the osmium-187 isotope promised fabulous profits. In 2004, official information about a contract with the Czech Republic for the sale of “curiosities” was announced.

But soon the passions for osmium subsided, and the information... was classified. When we decided to find out what happened to the potential “untold riches” from scientists and officials, we came across a blank wall...

We don't know anything, we won't say anything

For information on the osmium-187 isotope, we turned to the Tau-Ken Samruk mining company, since the strategic development priorities of this company clearly state: “production of rare earth metals”, “making profit from the implementation of subsoil use projects.” The company spent a long time preparing a response to our official request about the fate of the rare metal: as they explained, some information is not subject to disclosure. And as a result, they sent a reply: “The society does not have the full amount of information about the production of rare earth and rare metal products in Kazakhstan”...

Rarity is the main advantage

Then we turned to scientists. At the Institute of Geology, we managed to find a specialist who knows about osmium-187 firsthand. Head of the Laboratory of Physical and Chemical Research Methods Murat MADIN has been studying the isotope osmium-187 for decades. In Soviet times, it was the Institute of Geology that carried out research in this direction.

– Previously, rhenium was considered the rarest metal in the earth’s crust, but today it is most likely osmium. In Kazakhstan, these elements are available and are extracted industrially,” the scientist explained. – Their main value is that they are rare. But the most expensive thing is not even the metal itself, but the isotopes that are extracted from it.

Osmium is a radiogenic isotope. What does it mean? Radioactive decay of rhenium occurs in the deposit over many thousands of years, and as a result, osmium accumulates, which can be extracted along the way.

– There are osmium deposits in other countries, for example, in the USA, Russia, but the osmium-187 isotope is mined there using complex and expensive technologies. In Kazakhstan, osmium-187 is natural, it accumulates naturally, says Murat Madin.

Instead of a nuclear bomb - an information bomb?

Several years ago, osmium found itself at the center of an international scandal. Foreign media were full of catchy headlines: “Nuclear smuggling.” They even wrote that almost a nuclear bomb could be made from the osmium-187 isotope!

This, by the way, provoked demand for this rare metal. A whole chain of resellers has appeared, wanting to warm their hands on this. However, scientists say that this is not so much a nuclear bomb as an information bomb. Osmium is allegedly sometimes credited with properties that it does not possess.

– There is a lot of speculation around osmium. Some “experts” have exaggerated this topic, says Murat Madin. – It is known that, for example, the Oak Ridge Laboratory in the USA sells isotopes for nuclear scientists and large medical companies. But talking about nuclear weapons made from osmium is pointless...

Is Kazakhstani osmium traded in Russia?

Despite the veil of secrecy that covers osmium-187, any user can find offers for its sale and purchase on the Internet if desired. We came across an offer to buy several kilograms (!) of osmium-187 in... St. Petersburg. They called. At the other end of the line they said: yes, they really sell isotope-187, obtained from Kazakhstani raw materials. When we tried to find out from whom this raw material was purchased, the talkative seller, probably sensing something was wrong, avoided answering. He also did not inform about the price per gram of the isotope, saying that it is better to discuss such topics directly during the meeting.

It turns out strange: osmium is practically freely available! Although, for example, in 2009, an osmium trafficker who turned out to be a native of Kazakhstan was arrested in the Moscow region. A criminal case was initiated under the article “Illegal trafficking in precious metals.”

We sell, but not to everyone

However, as we found out, you can buy osmium in Kazakhstan. Officially. We called a company that has a license for this - at least that’s what the company’s employees assured us.

When asked whether they sell osmium-187, we were answered at length:

- The issue is being discussed. If they give us the go-ahead, we will sell. Please understand, this is a political issue...

We were also informed that there is osmium in stock, but even if they decide to sell it, it will not be sold to everyone. Rumor has it that such a deal would not be possible without the participation of special services and verification of the buyer. Selling this isotope later is not easy; such transactions do not take place on the stock exchange. Export abroad is also only by agreement. There are also restrictions on volumes, the minimum purchase is 5 grams, and that’s a lot of money!

Metal smells, money doesn't!

The word "osmium" means "smell". They say it was called that because when it is dissolved in alkali, an unpleasant, irritating odor appears, similar to both chlorine and garlic. But, as you know, money has no smell. Why does Kazakhstan, having reserves of such a unique metal, not make a profit? Or does it extract, but we don’t know it?

We called the National Center for Integrated Processing of Mineral Raw Materials, whose management several years ago announced information about transactions for the sale of osmium, and asked questions.

– Now there is a lull in this direction, the issue of implementation is problematic. As far as I know, osmium is stored until demand appears on the market. There are no secrets, they are simply escalating the situation to create excitement and increase the price. Reserves, processing technologies and volumes - yes, these are state secrets, all other information is open.

The specialist, telling us this information, asked not to refer to it, since she believes that there is no need to raise this topic today...

It turns out that wealth lies under our feet, but there is no demand for it. Osmium consumption in the world is just a few grams! Today, according to knowledgeable people, it is used to make... balls for expensive ballpoint pens!

So, maybe we should at least make souvenirs from this rare metal? After all, there is great interest in it; many foreigners who come to Kazakhstan, having read tales on the Internet, are not averse to buying an incomprehensible, odorous gray powder for a lot of money...

Yesterday on Yulia Latynina’s program I heard a story about a divorce with osmium-187.
Oh, how beautiful, just “let the song flow in the open air.”
I think this is one of the most elegant scams I've heard of.
I’m not afraid to use the now fashionable word - innovative scam.
Below the cut is an excerpt with a story about the divorce itself.

Now the United Russia party and the organizers of the competition claim that Petrik has nothing to do with this program. But let me remind you that earlier it was Gryzlov and Petrik who asked for 15 trillion rubles for this matter. And who is Petrik, especially for a country that... How is it there? Skolkovo, nanotechnology. Apparently, Petrik will sit with us in Skolkovo. This is a swindler in the most literal sense of the word, because under Soviet rule he received exactly his sentence under this article, a long one. Freed. He was mainly engaged in buying up inventions of various defense institutes.

For example, imagine that Petrik showed everyone fairings made of artificial spinel, a fairing for rockets. Those. it is transparent, it sits on the rocket, there is some kind of guidance head under it, everything is visible through it. And they went everywhere and said that Petrik did it. Imagine how the scientists from the State Optical Institute, who actually made these fairings, felt, who knew that only defective specimens were in the hands of various people who traded them.

There were many stories like this. But the most remarkable story, which, in my opinion, is the predecessor of “Clean Water” and explains why the highest officials of the state are involved in Petrik’s patronage, is the story of osmium-187. Before I talk about the history of osmium-187, I want to remind you that in St. Petersburg in the early 90s, this kind of semi-gangster scam was generally popular, when in all this self-generating economic soup, bandits heard that they could take out some kind of aluminum for a lot of money, copper, that there is a very big difference between the prices at which you buy internally and the prices at which you buy externally.

And the bandits also had strange ideas about reality. They always believed that there were some wonderful substances inside Russia that our defense industry created, that if you take them to the West, you will buy them for billions of dollars and get rich.

The first topic was some kind of alpha-fetoprotein. This is a biological substance that contributed to something there and was extracted from miscarriages. The inventor who made it, or allegedly made it, walked around in slippers on his bare feet, everyone who was not lazy stole from him - either bandits, or cops - and took away this alpha-fetoprotein.

But even if it helped in some way, it is clear that no one in the West bought it, because no Western pharmacological laboratory will buy from you an unknown substance that supposedly has miraculous properties without a certificate at all. What if they cooked it in the toilet at home and also spat in it? Then there was bee venom, then there was snake venom. It’s hard to say where there are snakes in St. Petersburg. But St. Petersburg bandits almost chartered planes to use this snake venom.

And the fourth on this wave was osmium-187, this is when in the early 90s an official of the St. Petersburg mayor’s office, Savenkov, was detained, who somewhere across the Finnish border in the left toe of his right shoe was carrying an ampoule containing 6 grams of the substance osmium-187 . He was detained. Why he was detained, who reported on him, this is very interesting. He did not have any documents to export this osmium. The FSB and all government agencies ran in and began to find out what kind of osmium it was and who needed it. It was needed much like alphafetoprotein.

What is osmium-187, which Petrik supposedly purified in the kitchen? There is a thing called the rhenium-osmium method for determining the age of a substance. The rhenium-osmium method is that there is rhenium, which has two isotopes, more or less stable, 185 and 187. 185 is completely stable, and 187 decays within 10 billion years, and decays into osmium-187, which is very convenient for dating. You take a piece of ore, see how much rhenium is in it, how much osmium-187 is in it, and you get a date.

And there is the Dzhezkazgan copper plant, whose dumps contain a lot of rhenium. Accordingly, the dumps of which, of all osmium isotopes, contain only osmium-187. Osmium has a lot of isotopes, and osmium-187 is indeed a very rare isotope, it occupies 1.6% of the total amount of osmium.

We must give Petrik his due - either he realized this, or it was suggested to him - indeed, by purely chemical means, from the dumps of the Dzhezkazgan copper plant, you can obtain not only osmium, namely osmium-187, because there is no other osmium there, because it is half-life product of rhenium.

The problem is that osmium-187 is not needed for anything. Those. not needed at all. There are no ways to use osmium, just as there are no ways to use many other expensive and well-known substances. At the prices of the Oak Ridge Laboratory, which generally dictates all prices for isotopes, osmium-187 is indeed very expensive. It costs 200 thousand dollars per gram, or 200 dollars per microgram. And it stands this way because all such isotopes, unnecessary isotopes, are obtained by the method of electromagnetic separation, when a purely chemical substance is divided into isotopes, and, accordingly, strips of the substance are deposited.

And the cost of isotopes in this case is directly proportional to the amount of money and effort spent on its isolation. And any isotope, of which there is very little, is therefore very expensive. The big problem is that he is expensive, but no one wants this elusive Joe because no one is looking for him. And the question is - you have a rare isotope, and it has a real price. But simply at this price no one will ever buy it, because no one needs it. What to do?

And here we return to this story with the detention of Savenkov. Look at the kind of advertising being created for osmium-187, a completely unnecessary substance that has no industrial use, as part of the arrest of Savenkov. All government agencies, all journalists, the FSB, the St. Petersburg authorities themselves begin to run around and find out why this osmium is needed.

They are creating a gigantic advertisement for this osmium. Every St. Petersburg bandit and every St. Petersburg banker knows that it costs 200 thousand dollars a gram and this is a terribly interesting thing. And even Vladimir Vladimirovich Putin himself - attention: Vladimir Putin - who then works in the St. Petersburg mayor’s office, gives an interview on March 17, 1994 to the newspaper “Evening Petersburg”, when he says that this is a very important and necessary invention for the city, osmium-187.

“The inventions created in the course of this work,” I quote Putin, “are patented, i.e. protected by law. I met with the inventor (for obvious reasons I do not mention his name) and discussed with him all the difficulties that had arisen. The scientist is ready to realize his discoveries…”, within the framework of the joint-stock company that Savenkov initially proposed to create.

And everyone is discussing whether the osmium was exported correctly or the osmium was exported incorrectly. And even Putin is participating in this advertising campaign for osmium-187. And no one asks the question - why is it needed?

What happens next? A letter comes to the Khlopin Radium Institute from abroad, which says: “Guys, we need 100 grams of osmium-187.” Imagine the early 90s. Or rather, this story with the radium institute, it even happened a little earlier, they coincided in time. A poor radium institute, scientists who put their teeth on the shelf.

And then they received this order from abroad. They run to the state reserve, they say: “Please give us 60 kilograms of pure osmium, we will isolate this damn isotope from it and sell it, because no one needs it anyway. Great, we’ll get fed.” After all, scientists at the Radium Institute - we must give them their due - did not realize that osmium could be obtained chemically from the dumps of the Dzhezkazgan copper plant.

They honestly followed the beaten path, they built a real centrifuge, calculated everything, the electromagnetic separation method is no longer profitable in such large quantities, they produced 100 grams of this osmium. Foreign customers have disappeared. They were left with osmium - and teeth on the shelf. 100 grams, supposedly 200 thousand dollars per gram.

What happens next? Our Russian customer already comes, some young guys, very good, they say: “Guys, we will buy this osmium from you.” How much do you think? Answer: “For 50 million dollars.” You think, what’s the hook? And these young guys say: “And osmium, it costs 200 thousand dollars per gram. Here you have 100 grams. We will pledge this osmium as collateral for a loan from a commercial bank of 200 million dollars, and after that we will pay you 50.” This is a brilliant story from the early 90s of St. Petersburg.

You can throw up your hands, because there is an undoubted knowledge of physics and human psychology (even more than knowledge of physics). I have absolutely no doubt that Mr. Petrik knows physics to the extent that he was known by medieval alchemists, who knew for sure that if you are brewing gold for a ruler and want to fool him, then you must put gold in hollow sticks, they They will burn, and you will take the gold out of the crucible.

But this is the story of the early 90s in St. Petersburg. And now this story, the same as with osmium-187, is being repeated with this very “Clean Water”, with filters for which there is a very serious question regarding the quality of cleaning. The Society of Russian Consumers, it seems, is even going to court now. And with filters, the manufacturing technology of which is nothing particularly new, this is a repetition of what happened in this small gangster Petersburg, lohast, in the early 90s.

And we see that the same people are participating. I, of course, understand that Vladimir Vladimirovich is no longer personally involved, if at all he participated in this osmium, if somehow this interview happened by chance. But all these people continue to be connected. And all these people, most likely, simply do not have the strength to resist Petrik. And it is paradoxical that a state that is not capable of extinguishing fires, is not capable of ensuring the safety of citizens, is not capable of providing protection from terrorism, it is capable of ensuring the prosperity of the inventor Victor Petrik.

Osmium is a chemical element with atomic number 76. In D.I. Mendeleev’s periodic table of chemical elements, it is designated by the symbol Os (lat. Osmium). Under standard conditions it is a silvery-bluish brittle transition metal. Belongs to the group of platinum metals. It has a high density, comparable in this parameter only to iridium (the densities of Os and Ir are almost equal, taking into account the calculated error).

Story

Osmium was discovered in 1804 by the English chemist Smithson Tennant in the precipitate remaining after dissolving platinum in aqua regia. Similar studies were carried out by French chemists Collet-Descoti, Antoine Francois de Fourcroix and Vauquelin, who also came to the conclusion that the insoluble residue of platinum ore contained an unknown element. The hypothetical element was given the name pten (winged), but Tennant's experiments demonstrated that it was a mixture of two elements - iridium and osmium.
Named from ancient Greek. ὀσμή (smell), based on the sharp-smelling volatile oxide OsO 4 (reminiscent of ozone).

Receipt

Osmium is isolated from enriched raw materials of platinum metals by calcining this concentrate in air at temperatures of 800-900 °C. In this case, vapors of the highly volatile osmium tetroxide OsO 4 are quantitatively sublimated, which are then absorbed by the NaOH solution.
By evaporating the solution, a salt is isolated - sodium perosmate, which is then reduced with hydrogen at 120 °C to osmium:
Na 2 + 3H 2 = 2NaOH + Os + 4H 2 O.

In this case, osmium is obtained in the form of a sponge.

Properties

Physical
Osmium is a grey-bluish, hard but brittle metal with a very high specific gravity that retains its luster even at high temperatures. Due to its hardness, brittleness, low vapor pressure (the lowest of all platinum metals), and very high melting point, osmium metal is difficult to machine. Osmium is considered the densest of all chemical elements, slightly exceeding iridium in this parameter. The most reliable densities for these metals can be calculated from the parameters of their crystal lattices: 22.562 ± 0.009 g/cm³ for iridium and 22.587 ± 0.009 g/cm³ for osmium. When comparing different isotopes of these metals, 192 Os is the densest. The unusually high density of osmium is explained by lanthanide compression.

Chemical
When heated, osmium powder reacts with oxygen, halogens, sulfur vapor, selenium, tellurium, phosphorus, nitric and sulfuric acids. Compact osmium does not react with either acids or alkalis, but forms water-soluble osmates with molten alkalis. Reacts slowly with nitric acid and aqua regia, reacts with molten alkalis in the presence of oxidizing agents (potassium nitrate or chlorate), and with molten sodium peroxide. In compounds it exhibits oxidation states from −2 to +8, of which the most common are +2, +3, +4 and +8.
Osmium is one of the few metals that form polynuclear (or cluster) compounds. Polynuclear osmium carbonyl Os 3 (CO) 12 is used to model and study the chemical reactions of hydrocarbons on metal centers. Carbonyl groups in Os 3 (CO) 12 can be replaced by other ligands, including those containing cluster nuclei of other transition metals.

Osmium is a chemical element with atomic number 76 in D. I. Mendeleev’s Periodic Table of Chemical Elements, designated by the symbol Os (lat. Osmium).

Atomic number - 76

Atomic mass - 190.23

Density, kg/m³ - 22500

Melting point, °C - 3000

Heat capacity, kJ/(kg °C) - 0.13

Electronegativity - 2.2

Covalent radius, Å - 1.26

1st ionization potential, eV - 8.70

History of the discovery of osmium

In 1804, the famous English scientist William Wollaston, having greatly intrigued the scientific world (more about this is described in the essay on palladium “The English Chemist’s Joke”), reported at a meeting of the Royal Society that, while analyzing raw (natural) platinum, he discovered in it previously unknown metals, which he named palladium and rhodium. Both were found in that part of the platinum that dissolved in aqua regia, but this reaction also left an insoluble residue. Like a magnet, it attracted many chemists, who rightly believed that some hitherto unknown element could be hidden in it.

The French Collet-Descotilles, Fourcroix and Vauquelin were close to success. They noticed more than once that when raw platinum was dissolved in aqua regia, black smoke was released, and when the insoluble residue was fused with caustic potassium, compounds were formed that “did not object” to dissolution.

Fourcroix and Vauquelin suggested that the desired element partially evaporates in the form of smoke, and that part of it that does not manage to “evacuate” in this way offers all possible resistance to the aggressor, not even wanting to dissolve in it. Scientists hastened to give the new element a name - “pten”, which in Greek means “winged, flying”.

But this name fluttered like a butterfly and sank into oblivion, since Tennant soon managed to separate the “chicken”: in fact, it was a natural alloy of two different metals. The scientist named one of them iridium - for the variety of colors of the salts, and the other - osmium, because its tetroxide, released when the product of fusion of osmiridium (as the former “pten” later became known) with alkali was dissolved in acid or water, had an unpleasant, irritating odor , similar at the same time to the smells of chlorine and rotten radishes. Later it turned out that the metal itself is capable of emitting a similar “aroma,” albeit weaker: finely ground osmium gradually oxidizes in air, turning into tetroxide.

Apparently, Tennant did not like this smell, and he angrily decided to immortalize his strongest impression from his first meeting with it in the name of the element he discovered.

They meet you by their clothes, they see them off by their intelligence. And if the smell and color - tin-white with a grayish-blue tint - can be considered the “clothing” of osmium, then its characteristics as a chemical element and as a metal, according to this proverb, should be attributed to “mind”.

So what can our hero boast of? First of all, as already mentioned, by its noble origin. Take a look at the periodic table of elements: on the right side, the platinum group, consisting of two triads, stands apart. The upper triad includes light platinum metals - ruthenium, rhodium, palladium (everything in the world is relative: any representative of this trinity is more than one and a half times heavier than iron). The second triad brought together real heavyweight heroes - osmium, iridium and platinum.

It is interesting that for a long time scientists adhered to this order of increasing atomic weights of these elements: platinum - iridium - osmium. But when D.I. Mendeleev created his periodic system, he had to carefully check, clarify, and sometimes correct the atomic weights of many elements. It was not easy to do all this work alone, so Mendeleev involved other chemists in the work. So, when Yu.V. was recommended to him. Lermontov, who was not only a relative of the great poet, but also a highly qualified chemist, the scientist asked her to clarify the atomic weights of platinum, iridium and osmium, since they caused him great doubt.

In his opinion, osmium should have the smallest atomic weight, and platinum should have the largest. A series of precise experiments conducted by Lermontova confirmed the correctness of the creator of the periodic law. Thus, the current arrangement of elements in this triad was determined - everything fell into place.

Osmium has not been found in native form. It is found in polymetallic ores that also contain platinum and palladium (sulfide copper-nickel and copper-molybdenum ores). The main minerals of osmium are natural alloys of osmium and iridium (nevyanskite and sysertskite) belonging to the class of solid solutions. Sometimes these minerals occur independently, but more often osmic iridium is part of native platinum. The main deposits of osmic iridium are concentrated in Russia (Siberia, the Urals), the USA (Alaska, California), Colombia, Canada, and the countries of South Africa. Osmium is also found in the form of compounds with sulfur and arsenic (erlichmanite, osmium laurite, osarsite). The osmium content in ores usually does not exceed 1·10−3%.

Together with other noble metals, it is found in iron meteorites.

In nature, osmium occurs in seven isotopes, 6 of which are stable: 184 Os, 187 Os, 188 Os, 189 Os, 190 Os and 192 Os. The heaviest isotope (osmium-192) accounts for 41%, the lightest isotope (osmium-184) only 0.018% of the total “reserves”. Osmium-186 is subject to alpha decay, but given its exceptionally long half-life of (2.0±1.1)×10 15 years, it can be considered practically stable. According to calculations, other natural isotopes are also capable of alpha decay, but with an even longer half-life, so their alpha decay was not observed experimentally. Theoretically, double beta decay is possible for 184 Os and 192 Os, which has also not been observed by observations.

The isotope osmium-187 is the result of the decay of the isotope rhenium (187 Re, half-life 4.56×10 10 years). It is actively used in dating rocks and meteorites (rhenium-osmium method). The best known use of osmium in dating methods is the iridium-osmium method, which was used to analyze quartz from the boundary layer separating the Cretaceous and Tertiary periods.

The separation of osmium isotopes is a rather complex task. This is why some isotopes are quite expensive. The first and only exporter of pure osmium-187 is Kazakhstan, which since January 2004 has officially offered this substance at prices of $10,000 per 1 gram.

Osmium-187 does not have widespread practical use. According to some reports, the purpose of operations with this isotope was the laundering of illegal capital.

• in the earth's crust - 0.007 g/t
• in peridotites - 0.15 g/t
• in eclogites - 0.16 g/t
• in dunite-peridotite formations - 0.013 g/t
• in pyroxenite formations - 0.007 g/t

Native osmium has not been found in nature. It is always associated in minerals with another platinum group metal - iridium. There is a whole group of iridium osmide minerals. The most common of these is nevyanskite, a natural alloy of these two metals. It contains more iridium, which is why nevyanskite is often called simply osmic iridium. But another mineral - sysertskite - is called osmium iridide - it contains more osmium... Both of these minerals are heavy, with a metallic luster, and this is not surprising - such is their composition. And it goes without saying that all minerals of the osmic iridium group are very rare.

Sometimes these minerals occur independently, but more often osmic iridium is part of native raw platinum. The main reserves of these minerals are concentrated in the USSR (Siberia, the Urals), the USA (Alaska, California), Colombia, Canada, and the countries of South Africa.

Naturally, osmium is mined together with platinum, but the refining of osmium differs significantly from the methods for isolating other platinum metals. All of them, except ruthenium, are precipitated from solutions, while osmium is obtained by distilling it off from volatile tetroxide.

But before distilling off OsO 4, it is necessary to separate iridium osmide from platinum, and then separate iridium and osmium.

When platinum is dissolved in aqua regia, the minerals of the iridium osmide group remain in the sediment: even this of all solvents cannot overcome these most stable natural alloys. To convert them into solution, the precipitate is fused with eight times the amount of zinc - this alloy is relatively easy to turn into powder. The powder is sintered with barium peroxide BaO 3 , and then the resulting mass is treated with a mixture of nitric and hydrochloric acids directly in a distillation apparatus to remove OsO 4 .

It is captured with an alkaline solution and a salt of the composition Na 2 OsO 4 is obtained. A solution of this salt is treated with hyposulfite, after which osmium is precipitated with ammonium chloride in the form of Fremy salt Cl 2 . The precipitate is washed, filtered, and then calcined in a reducing flame. This is how spongy osmium is not yet pure enough.

Then it is purified by treating with acids (HF and HCl), and further reduced in an electric furnace in a stream of hydrogen. After cooling, metal with a purity of up to 99.9% O 3 is obtained.

This is the classic scheme for obtaining osmium - a metal that is still used extremely limitedly, a metal that is very expensive, but quite useful.

High hardness and exceptional refractoriness make it possible to use osmium for coating friction units.

Osmium is the first element in density. Its density is 22.61 g/cm³.

Osmium is a tin-white metal with a grayish-blue tint. It is the heaviest of all metals and one of the hardest. However, osmium sponge can be ground into powder because it is fragile.

Hexagonal crystal lattice of Mg type, a = 0.27353 nm, c = 0.43191 nm, z = 2, spaces. group P6 3 /mmc;

Osmium melts at a temperature of about 3000°C, and its boiling point has not yet been precisely determined. It is believed to lie somewhere around 5500°C.

Metal density 22.61 g/cm 3 ; melting point 31.8 kJ/mol, evaporation temperature 747.4 kJ/mol; steam pressure 2.59 Pa (3000 °C), 133 Pa (3240 °C); 1.33kPa (3640°C), 13.3 kPa (4110°C); temperature coefficient of linear expansion 5·10 -6 K -1 (298 K); thermal conductivity 0.61 W/(cm K); conductivity 9.5 μΩ cm (20°C), temperature coefficient. Conductivity 4.2·10 -3 K -1; paramagnetic, magnetic susceptibility + 9.9·10 -6; transition temperature to the superconducting state 0.66 K; Vickers hardness 3-4 GPa, Mohs hardness 7; normal elastic modulus 56.7 GPa; shear modulus 22 GPa.

Like other platinum metals, osmium exhibits several valences: 0, 2+, 3+, 4+, 6+ and 8+. Most often you can find compounds of tetra- and hexavalent osmium. But when interacting with oxygen, it exhibits a valence of 8+.

When heated, osmium powder reacts with oxygen, halogens, sulfur vapor, selenium, tellurium, phosphorus, nitric and sulfuric acids. Compact osmium does not react with either acids or alkalis, but forms water-soluble osmates with molten alkalis. Reacts slowly with nitric acid and aqua regia, reacts with molten alkalis in the presence of oxidizing agents (potassium nitrate or chlorate), and with molten sodium peroxide. In compounds it exhibits oxidation states +4, +6, +8, less commonly others from +1 to +7.

In its compact state, osmium is resistant to oxidation up to 400 °C. Compact osmium does not dissolve in hot hydrochloric acid and boiling aqua regia. Finely dispersed osmium is oxidized by HNO 3 and boiling H 2 SO 4 to OsO 4, when heated, it reacts with F 2, Cl 2, P, Se, Te, etc. Metallic Os may. transferred into solution by fusion with alkalis in the presence of oxidizing agents, this forms salts of osmic acid H 2 OsO 4 -osmate (VI), which is unstable in the free state. When OsO 4 reacts with KOH in the presence of ethanol or by radiation with KNO 2, osmate(VI) K 2, or K 2 OsO 4 2H 2 O is also obtained. Osmate(VI) is reduced by ethanol to hydroxide Os(OH) 4 (black) , which in an atmosphere of N 2 is dehydrated to dioxide OsO 2. Perosmates M 2 are known, where X = OH, F, formed by the interaction of a solution of OsO 4 with a concentrated alkali solution.

A remarkable feature of osmium tetroxide is that its solubility in organic liquids is much higher than in water. So, under normal conditions, only 14 grams of this substance are dissolved in a glass of water, and more than 700 grams in a glass of carbon tetrachloride.

In an atmosphere of sulfur vapor, osmium powder flares up like a match, forming sulfide. Omnivorous fluorine at room temperature does not cause any “harm” to osmium, but when heated to 250-300 C, a number of fluorides are formed. Since the two volatile osmium fluorides were first prepared in 1913, their formulas were thought to be OsF6 and OsF8. But in 1958 it turned out that OsF8 fluoride, which had “lived” in chemical literature for almost half a century, never actually existed, and the indicated compounds corresponded to the formulas OsF5 and OsF6. Relatively recently, scientists managed to obtain another fluoride, OsF7, which, when heated above 100 C, decomposes into OsF6 and elemental fluorine.

One of the main advantages of osmium is its very high hardness; In this, few metals can compete with it. That is why, when creating alloys with the highest wear resistance, osmium is introduced into their composition. Fountain pens with a gold nib are not uncommon. But gold is a rather soft metal, and over many years of work, the pen has to travel long kilometers on paper at the will of its owner. Of course, paper is not a file or emery, but only a few metals can withstand such a test. And yet the tips of the feathers cope with this difficult role. How? The secret is simple: they are usually made from alloys of osmium with other platinoids, most often from osmiridium, which you already know. Without exaggeration, we can say that a pen “armored” with osmium cannot be demolished.

Exceptional hardness, good corrosion resistance, high wear resistance, and lack of magnetic properties make osmiridium an excellent material for the point of a compass needle, axes and supports of the most precise measuring instruments and clock mechanisms. Cutting edges of surgical instruments and cutters for artistic processing of ivory are made from it.

The fact that osmium and iridium often “act as a duet” - in the form of a natural alloy, is explained not only by the valuable properties of osmiridium. but also by the will of fate, which wished that in the earth’s crust these elements were connected by unusually strong bonds. Neither metal has been found in the form of nuggets in nature, but iridium osmide and osmium iridium are well-known minerals (they are called nevyanskite and sysertskite, respectively): iridium predominates in the first, osmium in the second.

Sometimes these minerals occur independently, but more often they are part of native platinum. Its separation into components (the so-called refining) is a process that includes many stages, at one of which osmiridium precipitates. And perhaps the most difficult and expensive thing in this whole “story” is to separate osmium and iridium. But often this is not necessary: ​​as you already know, the alloy is widely used in technology, and it costs much less than, for example, pure osmium. After all, in order to isolate this metal from an alloy, it is necessary to carry out so many chemical operations that just listing them would take up a lot of space. The end product of a long process chain is metallic osmium with a purity of 99.9%.

Along with hardness, another advantage of osmium is known - refractoriness.

In terms of melting point (about 3000 C), it surpassed not only its noble brothers - platinoids, but also the vast majority of other metals. Thanks to its refractoriness, osmium found its way into the biography of the electric light bulb: back in the days when electricity was proving its superiority over another source of light - gas, the German scientist K. Auer von Welsbach proposed replacing the carbon fiber in an incandescent lamp with an osmium one. The lamps began to consume three times less energy and provided a pleasant, even light. But osmium did not last long in this important position: at first it was replaced by the less scarce tantalum, but soon it was forced to give way to the most refractory of refractories - tungsten, which to this day maintains its fiery watch.

Something similar happened with osmium in another area of ​​its application - in the production of ammonia. The modern method for the synthesis of this compound, proposed back in 1908 by the famous German chemist Fritz Haber, is unthinkable without the participation of catalysts. The first catalysts that were used for this purpose showed their abilities only at high temperatures (above 700 C), and besides, they were not very effective.

Attempts to find a replacement for them did not lead to anything for a long time. Scientists from the laboratory of the Higher Technical School in Karlsruhe said a new word in improving this process: they proposed using finely dispersed osmium as a catalyst. (By the way, being very hard, osmium is at the same time very fragile, so a sponge of this metal can be crushed and turned into powder without much effort.) Industrial experiments have shown that the game is worth the candle: the temperature of the process was reduced by more than 100 degrees, yes and the output of finished products has increased significantly.

Despite the fact that later osmium had to leave the scene here too (now, for example, inexpensive but effective iron catalysts are used for the synthesis of ammonia), it can be considered that it was it that moved an important problem off the ground. Osmium continues its catalytic activity to this day: its use in hydrogenation reactions of organic substances gives excellent results. This is primarily due to the high demand for osmium from chemists: almost half of its global production is spent on chemical needs.

Element 76 is also of considerable interest as an object of scientific research. Natural osmium consists of seven stable isotopes with mass numbers 184, 186-190 and 192. It is curious that the lower the mass number of the isotope of this element, the less common it is: if the heaviest isotope (osmium-192) accounts for 41%, then the lightest of the seven “brothers” (osmium-184) has only 0.018% of the total “reserves”. Since isotopes differ from each other only in the mass of atoms, and in their physicochemical “inclinations” they are very similar to each other, it is very difficult to separate them. That is why even “crumbs” of isotopes of some elements are incredibly expensive: for example, a kilogram of osmium-187 is estimated on the world market at $14 million. True, scientists have recently learned to “separate” isotopes using laser beams, and there is hope that soon the prices for these “non-consumer goods” will be noticeably reduced.

Of the osmium compounds, its tetroxide is of greatest practical importance (yes, the same one to which the element owes its name). It acts as a catalyst in the synthesis of certain drugs. In medicine and biology, it is used as a staining agent for microscopic examination of animal and plant tissues. It should be remembered that the seemingly harmless pale yellow crystals of osmium tetroxide are a strong poison that irritates the skin and mucous membranes and is harmful to the eyes.

Osmium oxide is used as a black dye for painting on porcelain: salts of this element are used in mineralogy as strong etchants. The majority of osmium compounds, including various complexes (osmium exhibits the ability to form complex compounds inherent in all platinum metals), as well as its alloys (except for the already known osmiridium and some alloys with other platinoids, tungsten and cobalt), are still “languishing” in waiting for the right job.