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Old 4th June 2012, 12:01 PM   #693
Oystein
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Originally Posted by chrismohr View Post
Oystein,
Last Friday Richard Gage told me personally that some of the iron-rich spheres found in the Bentham paper were only about 100 atoms across. Is this true? That would be ultra-nano if it were! He thinks Millette may not have looked at this closely enough.
Let's see...

Iron oxide, Fe2O3, has a density of about 5.2 g/cm3 and a molar mass of 159.7 g/mol. So one mol occupies a volume of (159.7/5.2) cm3 = 30.7 cm3 = 3.7*10-5 m3. The edges of cube of that volume are 0.031 m long (3.1 cm), that is 310,000,000 nm.

1 mole is about 6.0 1023. The cubic root of that number, 84,343,266, would be the number of molecules along the edge if you arrange 1 mole in a cube.

So if iron oxide molecules were in a cubic crystal structure, you'd find 84,343,266 molecules per 31,000,000 nm, or 0.37 nm per molecule, or 37 nm per 100 molecules.

The iron oxide pigments in the red paint are typically 100-150 nm across, that would be 270-405 molecules.

This would be somehat different for different materials, but I think we get an idea here of the orders of magnitude that we are talking about.
Iron: 23 nm / 100 atoms.
Silica: 34 nm / 100 atoms
etc.

So Gage is claiming that there are microspheres in the Bentham paper that are about 20-40 nm across? Let me check...

Nope, I see none post-ignition spheres smaller than 1 micron, all are larger than 1,000 nm, or more than 2500 atoms/molecules across.

However, as I said, the iron oxide pigments are close to that order of magnitude, they are only a few 100 molecules across. Perhaps he (or you?) mixed up pre-ignition grains and post-ignition spheres?

100 nm iron oxide pigments have been state of the art for 100 years and are easily and cheaply produced on large industrial scales by entirely conventional means: Chemical reaction, grinding and sieving, and are thus found in millions of mundane products.
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