Magnetic Nanoparticles Flashcards
What are the 4 ways we make nanoparticles?
1) Chemical based techniques 2) Physical vapour deposition 3) Electron beam lithography 4) Exploiting nature
Give an example of a chemical based technique to make nanoscale objects
Nanoparticle synthesis in solutions
Give an example of a physical vapour depositon technique used to make nanoscale objects
atom-by-atom approach, for example nanofilms, nanoclusters, nanodiscs
Give an example of an electron beam lithography technique used to make nanoscale objects
‘carving’ nanostructures from larger scale material
Give an example of exploiting nature in making nanoscale objects
iron oxide nanoparticles from magnetotactic bacteria
Why do we use MAGNETIC nanoparticles?
Because we can use magnetic fields to control nanoparticles!
What can we use magnetic field to DO to the particles? 6 things
1) positioning or targeting 2) mechanical stimulation of cells 3) generation of heat 4) separating mixtures 5) assays/biomarkers 6) imaging detection
Draw out the life cycle of a magnetic nanoparticle
Go girl g g go go gooo
What are the four forms of magnets?
1) paramagnets 2)ferro/ferrimagnets 3)superparamagnets 4)diamagnets
Define a ferro/ferrimagnet
There is a strong attraction between N and S of magnets. Easy to draw too ;)
Define a diamagnet
There is a weak repulsion between N and N. Repelled by magnetic fields
Define a paramagnet
Weak attraction between N/S
What is a diamagnet repelled by?
magnetic fields
What is the equation for magnetic susceptibility and what do the constituents mean?
X = M/H - M is the magnetisation of the substance and H is the applied magnetic field
How can we determine the magnetic nature of a substance?
By measuring how the magnetisation of the substance (M) varied in an applied magnetic field (H). Magnetic susceptibility equation.
What is a paramagnet attracted by?
An externally applied magnetic field.
Talk about how a paramagnet is made, particle wise.
Thermal motion randomises spin orientations, so paramagnets do not retain any magnetisation in the absence of an externally applied magnetic field, however PM materials have permanent dipoles in abs of mag field due to unpaired electrons just no direction bc of thermal motion. Magnetic field dipoles align with field, leading to movement in direction of applied field.
Do paramagnets retain any magnetisation in the abs of an externally applied magnetic field?
No, they retain their dipoles as they are perm due to unpaired electrons, but their movemnt is randomised due to thermal instability so NO magnetisation
What is the link between paramagnets and absolute 0?
Some paramagnets retain magnetisation at absolute 0 - this is known as being paramagnetic at ground state.
What is the magnetisation like for a paramagnet in the presence of a field?
Small, because only a few spins are oriented by the field.
Describe how ferromagnetism comes about
After the events described in paramagnetism, if the energy exchange between dipoles is great enough, this results in a ferromagnet - a permanant magnet. These have a large magnetic susceptibility
What kind of a magnetic susceptibility do ferromagnets have?
large
Describe diamagnets and their workings
When a magnetic field is applied, a small opposing magnetisation occurs. Small magnetic susceptibility.
What kind of a magnetic susceptibility do diamagnets have?
SMall
