bbartlog - 23-7-2014 at 11:15
What fundamental forces or factors make it difficult to make very small particles? Or to put it another way, why do even very tiny (nanometer-scale)
particles, which require special techniques to manufacture, still contain hundreds or thousands of individual atoms?
Some background information (more or less, the paper than made me wonder about this): http://pages.csam.montclair.edu/~yecko/ferro/oldpapers/DIREC...
For example, a 10nm diameter sphere of iron (atomic diameter 0.28nm) contains tens of thousands of iron atoms. Assuming that Fe is being precipitated
rapidly, or undergoing some kind of salt pyrolysis reaction, why does it want to accumulate in these large (from the atomic perspective) clumps? Are
they thermodynamically more favorable for some reason? Are there small-scale forces that pull them together? Or do the reactions that give rise to
them tend to take place at certain places rather than evenly throughout the reaction medium?
IrC - 23-7-2014 at 14:14
Particles with a strong electric dipole would tend to clump even though Brownian motion was trying to keep them apart. Charge to mass ratio would also
be a factor. Having particles that were closer to neutral or at least with a weaker field around them would aid in avoiding clumping.