Nano- and metamaterials

[EileenSchuh]

Could someone please explain to me the differences between nanomaterials and metamaterials? Are nanomaterials a type of metamaterial? Are the two terms interchangeable? Completely different?

[Xittenn]

Not at all the same Nanomaterial Engineering is the practice of engineering materials for nano-technology, whereas Metamaterial Engineering is the process of engineering materials to have a property that isn't normally observed such as invisibility. For example a metamaterial may be produced that renders objects within invisible or is simply itself invisible. Current research employs surface plasmon resonance to achieve a negative refractive index in hopes of gaining this property. A scientist here is noted as having introduced me to the concept. As for nanomaterials, buckyballs would be considered a nanomaterial.

[EileenSchuh]

I must agree that invisibility isn't normally observed. I understand that invisibility is one characteristic of metamaterials that scientists are trying to create/are creating and that there are others such as characteristics that manipulate sound waves in lieu of light waves.

 

However, my question remains: If metamaterial scientists are manipulating matter at the atomic or molecular level to create these non-normal material characteristics, is that not nanotechnology? nanomaterials?

Edited March 6, 2012 by EileenSchuh

[Xittenn]

Does a metamaterial necessitate nano or simply a process whereby the material is achieved? Piercing holes in foil doesn't exactly constitute nano. It might rely on the atomic and molecular properties of the constituents but these properties I do not believe are generally manipulated at the nano scale where metamaterials are concerned. This obviously doesn't mean that they couldn't be.

 

There are better opinions than mine and I'm not trying to close the subject!

Edited March 6, 2012 by Xittenn

[Klaynos]

Metamaterial is quite a wooly term. It broadly speaking means engineering a material to have physical properties not observed in nature.

 

The most common use of this term is for electromagnetic materials. And in that the most media talked about ones are negative refractive index materials. Normally these are narrow band and at microwave frequencies. Arrays of split ring resonanators and the like of the order milimeters or centimeters. The feature sizes are subwavelength.

 

Nanomaterials, again a broad term, are those which have been engineered to have nanoscale structure.

 

A metamaterial engineered for optical frequencies (~550nm) will have nanoscale features and therefore can be discussed as both a nanomaterial and a metamaterial.

 

Of cource invisibility is also a poorly defined term. If something is not visible at one frequency is it invisible? Most of us would say no, the media likes to not only say yes, but also call it invisible when the frequency is not even in the visible regime. How much reflection and absorption can you cope with before something is invisible? Glass could be defined as invisible if you make your definitions broad enough without being obsurd, or if we're talking microwaves then wood is pretty invisible polystyrene moreso... But at THz frequencies glass is massivly absorbing.

[EileenSchuh]

Is my understanding correct? -- If we are arranging or otherwise manipulating matter in ways to create materials with "un-natural" or novel characteristics , that would be metamaterial technology. If we are manipulating this matter at the level of atoms and/or subatomic particles that is nanomaterials and nanotechnology. Not all metamaterial is nanomaterial and not all nanotechnology involves materials but can involve things like devices and structures.

 

Am I getting closer?

[Xittenn]

Sounds good to me! : D