Is Osmium Harder than Diamond?

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Discussion Overview

The discussion centers around the hardness of osmium compared to diamond, exploring the implications of recent findings that suggest osmium may be harder than diamond. Participants examine the potential applications of osmium in industrial contexts, its manufacturing challenges, and comparisons with other materials.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Some participants reference a study indicating that osmium has a higher hardness than diamond, with specific measurements of bulk modulus for both materials.
  • Others question whether osmium could replace diamond in industrial applications, expressing curiosity about its practical use and production efficiency.
  • A participant introduces the idea that nanocrystalline carbon nitride may be harder than diamond, noting that this claim is still controversial.
  • There is a discussion about the complex extraction process of osmium, highlighting its rarity and the challenges associated with its production.
  • Some participants argue that while osmium may be more resistant to pressure, diamond remains superior in terms of scratch resistance.
  • One participant shares historical context about the rarity of osmium, mentioning a request during the Manhattan Project that exceeded the known supply of osmium.

Areas of Agreement / Disagreement

Participants express differing views on the hardness comparison between osmium and diamond, with some supporting the findings of osmium's hardness and others emphasizing diamond's scratch resistance. The discussion remains unresolved regarding the practical implications of osmium's hardness and its potential applications.

Contextual Notes

Limitations include the dependence on specific experimental conditions for hardness measurements and the unresolved nature of the claims regarding other materials like nanocrystalline carbon nitride.

Orion1
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Osmium turns out to be harder than diamond:

H Cynn and colleagues at Lawrence Berkeley National Laboratory have established that the metal osmium has a higher hardness than diamond. The team placed a 60-mkm-across osmium sample in a diamond anvil cell and compressed it to 60 GPa. The bulk modulus of osmium as calculated from lattice spacing changes measured by x-ray diffraction was found to be K=462 GPa - to be compared with 443 GPA in diamond. This discovery came as a great surprise because osmium differs considerably from other large-K materials in its crystal structure. Osmium is a relatively heavy metal with a hexagonal structure, whereas diamond, for example, is a light material whose atoms are covalently bonded into a cubic structure.

Reference:
http://prl.aps.org
 
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So, being harder than diamond, could osmium replace it as the primary material used for drilling and other industrial-related uses that require extra hard substances? I don't suppose they've found a way to produce this extra tough osmium efficiently, have they? Either way, this is a surprise to myself and I'm sure to others who have always thought of diamond as the single hardest natural substance on Earth ( it was believed to be the hardest, right?). I wonder what other applications researchers will find for osmium, assuming that it can be used in a practical way.
 
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Do you think diamonds might form better in singing pressaures?

Might singing pressaure help in fussion?
 
It doesn't look like osmium can be easily manufactured, it has a complex extraction process:

Preliminary treatment of the ore or base metal byproduct is required to remove silver, gold, palladium, and platinum. The residue is melted with sodium bisulphate (NaHSO4) and the resulting mixture extracted with water to give a solution containing rhodium sulphate, Rh2(SO4)3. The insoluble residue contains the osmium. The residue is melted with Na2O2 and extracted into water to extract the ruthenium and osmium salts (including [RuO4]2- and [OsO4(OH)2]2-). The residue contains iridium oxide, IrO2. Reaction of the salt with chlorine gas gives the volatile oxides RuO4 and OsO4. The osmium oxide is dissolved by treatment with alcoholic sodium hydroxide to form Na2[OsO2(OH)4], and the osmium precipiated out as pure OsCl2O2(NH3)4 by treatment with NH4Cl. Evaporation to dryness and burning under hydrogen gas gives pure osmium. (From: http://www.webelements.com/webelements/elements/text/Os/key.html)
 
Osmium may be more resistent to pressure, but diamond is still more resistent to being scratched/cut.
 
Scratch Match...

Osmium may be more resistent to pressure, but diamond is still more resistent to being scratched/cut.

p = 60 GPa - pressure:

Bulk Modulus: (Hardness)
K = 462 GPa - Osmium
K = 443 GPA - Diamond

This is true under normalized mineralogical/solid state conditions, however the 'scratch test' is a simple test of a minerals/material's 'Hardness'. Therefore, under conditions where p = 60 GPa, Osmium can 'scratch' a diamond and a diamond cannot 'scratch' Osmium.
 
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Osmium is rare - very rare. No, even rarer than that.

During the Manhatten project, the scientists made a request for a 10" sphere of osmium. The request was denied because it was several times more than the entire world's known supply of osmium.

The only widespread application that I know about for osmium is microprobe tips.

Njorl
 
You can buy a http://www.element-collection.com/html/collections.html
 
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  • #10
Nim said:
You can buy a http://www.element-collection.com/html/collections.html

"...and if you act now, for a limited time only, you get Lawrencium!"

Njorl
 
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