User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2010/02/10/PBL1: Difference between revisions
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[[Category:Nanoparticles course]] | [[Category:Nanoparticles course]] | ||
==Problem== | ==Problem statement== | ||
In class, we were given a [http://docs.google.com/View?id=dnw5v2k_49cdkgqzc5 problem] and an associated [http://docs.google.com/View?id=dnw5v2k_488hdx85dg grade sheet]. My portion of the presentation is Part B stated in the problem sheet. Below, I have outlined what I must talk about. | In class, we were given a [http://docs.google.com/View?id=dnw5v2k_49cdkgqzc5 problem] and an associated [http://docs.google.com/View?id=dnw5v2k_488hdx85dg grade sheet]. My portion of the presentation is Part B stated in the problem sheet. Below, I have outlined what I must talk about. | ||
* Iron nanoparticles | * Iron nanoparticles | ||
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</math> | </math> | ||
</center> | </center> | ||
:'''M''' is the resulting magnetization | |||
:''χ'' is the [http://en.wikipedia.org/wiki/Magnetic_susceptibility magnetic susceptibility] | |||
:'''H''' is the auxiliary [http://en.wikipedia.org/wiki/Magnetic_field magnetic field], measured in amperes/meter | |||
:''T'' is absolute temperature, measured in kelvins | |||
:''C'' is a material-specific [http://en.wikipedia.org/wiki/Curie_constant Curie constant] | |||
Or, more generally as: | Or, more generally as: | ||
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The magnetization of a paramagnet depends linearly on the external magnetic field and inversely on the temperature. | The magnetization of a paramagnet depends linearly on the external magnetic field and inversely on the temperature. | ||
</center> | </center> | ||
===[http://en.wikipedia.org/wiki/Ferrimagnetism Ferrimagnetism]=== | |||
Ferrimagnetism is a property of materials in which the magnetic moments of the atom will align themselves with an external electric field but, sublatices |
Revision as of 11:28, 10 February 2010
Problem statement
In class, we were given a problem and an associated grade sheet. My portion of the presentation is Part B stated in the problem sheet. Below, I have outlined what I must talk about.
- Iron nanoparticles
- Properties
- Advantages for their use
- Disadvantages for their use
- Coatings
- Nobel metals
- Silica
- Oxides
- Polymers
- Discuss the above coatings and how:
- They prevent degradation from oxygen and H2O.
- The coatings affect the iron nanoparticle properties.
This is a problem based learning exercise that necessitates group activity. The members of my group are dealing with Part A outlined in the problem sheet where they have doled out the various parts of making a quantum dot for a specific biological investigation. Their components include: picking a target (one person), synthesis of the quantum dot (one person), and characterization of the quantum dot (one person). It looks like I got the short end of the stick here...
Introduction
Since I will be dealing with magnetic iron nanoparticles, I need to explain what the terminology means for magnets.
Diamagnetism
Some materials will actually deflect external magnetic fields such that they can exclude the external magnetic field from going through them. An example is the picture below which show pyrolytic carbon, taken from Wikipedia's article on diamagnetism.
http://upload.wikimedia.org/wikipedia/commons/c/c9/Diamagnetic_graphite_levitation.jpg
Insert picture of field lines going through a material
Another cool image is this movie which shows a levitating frog.
Heuristically, diamagnetism comes from the material producing an opposing magnetic field that excludes the external magnetic field.
Paramagnetism
Paramagnetism is a weak effect of materials and can only be detected when an external magnetic field is applied. Paramagnets follow Curie's law (if the magnetization of the material is weak) which can be stated as:
[math]\displaystyle{ \boldsymbol{M} = \chi \cdot\boldsymbol{H}=C\cdot \frac{\boldsymbol{H}}{T} }[/math]
- M is the resulting magnetization
- χ is the magnetic susceptibility
- H is the auxiliary magnetic field, measured in amperes/meter
- T is absolute temperature, measured in kelvins
- C is a material-specific Curie constant
Or, more generally as:
The magnetization of a paramagnet depends linearly on the external magnetic field and inversely on the temperature.
Ferrimagnetism
Ferrimagnetism is a property of materials in which the magnetic moments of the atom will align themselves with an external electric field but, sublatices