# Continuum of nanoparticles (cobalt ) meaning

Joined May 11, 2018
158
Hello i am doing an excercise and they asked me to tell if a cobalt crystal is continuum or not ?
But i don't know the meaning of continuum , and can not find it on internet either . Can you please give me the definition of continuum ?
like continuum of cobalt nanoparticle

thanks

#### jpanhalt

Joined Jan 18, 2008
11,088
Sure:

#### Papabravo

Joined Feb 24, 2006
16,837
It is known that hcp (hexagonal close packed) and fcc (face centered cubic) are equivalent in the sense that they represent the densest possible packing of sphere of identical radius. This packing factor is:
$\frac{\pi}{3\sqrt{2}}\;\approx\;0.74048$
On an atomic distance scale there is observable empty space so treating such a structure a a continuum seems a bit dubious. The distance between the centers of the atomic spheres can be measured by X-ray diffraction. At larger distance scales you can of course treat it as a continuum.

With respect to the nonoparticles, They are normally specified as limited to a particular size, so again we need to know the distance scale we are dealing with. Are we dealing with an atomic distance scale or a particle size distance scale.

#### sparky 1

Joined Nov 3, 2018
580
The following sentence show an example of usage. It can be found under subheading abstract.
The ﬁnal material microstructure was composed by cobalt clusters embedded into a continuum cobalt thiolate matrix.
In this sentence continuum refers to a stage at which the physical parts are joined into a continuum viewed macroscopic.

The workhorse on which the simulator runs is powered by complex quantitative expressions like these.
https://journals.sagepub.com/doi/full/10.1177/1687814016677022
After crunching numbers and optimizing statistically the output is a repetitive continuum as stated in the posts above.
PPT presentation summarizes the general concept put together uses term continuum
https://www.slideserve.com/yates/nanotechnology-in-mechanical-engineering

Last edited:

Joined May 11, 2018
158
It is known that hcp (hexagonal close packed) and fcc (face centered cubic) are equivalent in the sense that they represent the densest possible packing of sphere of identical radius. This packing factor is:
$\frac{\pi}{3\sqrt{2}}\;\approx\;0.74048$
On an atomic distance scale there is observable empty space so treating such a structure a a continuum seems a bit dubious. The distance between the centers of the atomic spheres can be measured by X-ray diffraction. At larger distance scales you can of course treat it as a continuum.

With respect to the nonoparticles, They are normally specified as limited to a particular size, so again we need to know the distance scale we are dealing with. Are we dealing with an atomic distance scale or a particle size distance scale.
hello @Papabravo Thanks . you made me do a research about packaging(packing structure) ; things that i had not looked into since i have been studying nanoscience but now i understand about the HCP and FCC. but about your question, in my questionaire we are talking about the atomic distance ( inter atomic layers to be specific) where the inter- atomic distance is 2.5A

#### Papabravo

Joined Feb 24, 2006
16,837
hello @Papabravo Thanks . you made me do a research about packaging(packing structure) ; things that i had not looked into since i have been studying nanoscience but now i understand about the HCP and FCC. but about your question, in my questionaire we are talking about the atomic distance ( inter atomic layers to be specific) where the inter- atomic distance is 2.5A
At that scale the only way you get a continuum is to create a matrix of cobalt nano particles with something smaller to fill up the available space. Maybe a thiolate of cobalt