ferromagnetic nanomaterials

1. Ferromagnetic Nanomaterials
Farah Salim
2014-2015

2. Content:
▶Introduction to magnetic nanomaterials.
▶Magnetic properties.
▶Ferromagnetic materials.
▶Effects of temperature and the magnetic field on
ferromagnetic materials.
▶Basic properties of ferromagnetic materials.
▶Methods of Preparation.
▶Applications.

3. Introduction
• Magnetic nanoparticles are a class of nanoparticle
which can be manipulated using magnetic field.
• Such particles commonly consist of magnetic
elements such as ferromagnetic metals (iron,
nickel and cobalt), alloys and oxides.
• Require size control and narrow size distribution.
• Perform best in the size range 10-20 nm in
various applications.

4. Magnetic Properties
Material
Magnetic (with unpaired electron).
Non-magnetic or diamagnetic (electrons all
paired up).

5. A material is considered ferromagnetic if it can be
magnetized. Materials with a significant Iron, nickel or
cobalt content are generally ferromagnetic.
Ferromagnetic materials are made up of many regions in
which the magnetic fields of atoms are aligned. These
regions are call magnetic domains.
Magnetic domains point randomly in demagnetized material,
but can be aligned using electrical current or an external
magnetic field to magnetize the material.
Ferromagnetic Materials

6. observable magnetic properties that are commonly
associated with ferromagnetic materials are:
1. Magnetic saturation.
2. Magnetic remanance.
3. Coercivity.
These observable properties are characterized by
measuring the magnetic moment of a material as a
function of an applied magnetic field. A sample
magnetization vs. applied magnetic field curve can be
seen in next figure.
Basic properties of ferromagnetic materials

7. Figure (1): Representative plot of magnetization measured
as a function of applied magnetic field for a ferromagnetic
material.

8. Effect of Temperature
Figure (2): Effect of temperature on magnetic materials.

9. Effect of the applied magnetic field
Figure (3): Ferromagnetic
particles under the influence
of an external magnetic
field.
Figure (4): Ferromagnetic
particles in absence of an
external magnetic field.

10. Methods of preparation:
1. Co-precipitation:
This method may be the most promising one because of its
simplicity and productivity. It is widely used for
biomedical applications because of ease of implementation
and need for less hazardous materials and procedures.
Co-precipitation is specifically the precipitation of an
unbound "antigen along with an antigen-antibody
complex" in terms of medicine. The reaction principle is
simply as:

11. 2. Thermal decomposition.
The decomposition of iron precursors in the presence of hot organic
surfactants has yielded markedly improved samples with good size
control, narrow size distribution and good crystallinity of individual
and dispersible magnetic iron oxide nanoparticles.
Figure (4):
Synthesis of
iron oxide by
thermal
decomposition
method.

12. 3. Micro emulsion ( reverse micelle method).
Water-in-oil (W/O) micro emulsions systems, a fine micro
droplets of the aqueous phase trapped within assemblies of
surfactant molecules dispersed in a continuous oil phase.
The surfactant-stabilized micro cavities (typically in the
range of 10 nm) provide a confinement effect that limits
particle nucleation, growth, and agglomeration.
Figure (5):
Reverse micelle

14. Applications
1. Nanomagnetism.
Figure (6): The general trend for most ferromagnetic
materials of coercivity as a function of particle size.

15. Figure (7): The balance of energies at hand in
determining the formation of single domain or multi-
domain ferromagnetic particles.
1. Nanomagnetism.

16. 1. Nanomagnetism.
Figure (8): (a)The coercivity of various anisotropic particle
shapes as a function of aspect ratio, (b) A pictorial
representation of each anisotropic particle shape.

17. 2. Targeted drug delivery.
Figure (9): Principle of targeted drug delivery system .

18. Because of their small sizes, nanoparticles are taken by cells where
large particles would be excluded or cleared from the body
1. A nanoparticle carries the pharmaceutical agent
inside its core, while its shell is functionalized with a
‘binding’ agent.
2. Through the ‘binding’ agent, the ‘targeted’
nanoparticle recognizes the target cell. The
functionalized nanoparticle shell interacts with
the cell membrane.
3. The nanoparticle is ingested inside the cell, and
interacts with the biomolecules inside the cell.
4. The nanoparticle particles breaks, and the
pharmaceutical agent is released.
Figure (10): Targeted
drug delivery.

19. Healthy tissue Sick tissue treated
with non-targeted
nanoparticles
Sick tissue treated with targeted nanoparticles
Figure (11): Example of a tissue treated by targeted drug delivery
system.

20. Laboratory research has established that nanoscale metallic
iron is very effective in destroying a wide variety of
common contaminants. The basis for the reaction is the
corrosion of zero valent iron in the environment:
3. Zero valent iron for ground water remediation.
The use of nZVI for groundwater remediation represents,
the most widely investigated environmental
nanotechnological technique.

21. Two approaches to application of ZVI for
Ground water remediation:
1. Granular ZVI in the form of reactive barriers has been
used for many years at numerous sites all over the world
for the remediation of organic and inorganic
contaminants in groundwater as shown in figure a.
Figure (12):
Conventional
reactive
barrier using
granular ZVI.

22. 2. With nZVI, two possible techniques are used:
A. Immobile nZVI is injected to form a zone of iron
particles adsorbed on the aquifer solids as shown in
figure b.
Figure (13):
Injection of
nZVI to form
an immobile
Reaction zone.

23. B. Mobile nZVI is injected to form a plume of reactive Fe
particles that destroy any organic contaminants that
dissolve from a DNAPL (dense non-aqueous phase liquid)
source in the aquifer as shown in figure c.
Figure (14):
Injection of
mobile nZVI .

24. Thank you