The document discusses the properties of nanomaterials, including their optical, electrical, mechanical, magnetic, and chemical characteristics, which are significantly influenced by their nanoscale size (1-100 nm). It highlights how size affects light absorption, electrical conductivity, mechanical strength, and reactivity, leading to unique behaviors such as superparamagnetism and changes in melting points. Additionally, it illustrates the differences in properties between bulk materials and nanoparticles, emphasizing their potential applications in various fields.

1. NANOMATERIALS
Abdullah Ahad
Department of
Chemistry
University of Rajshahi

2. Properties of Nanomaterials
Optical Electrical Mechanical Magnetic Chemical
Some common type of feature of nanomaterials are-
• Size 1-100nm
• Chemically active
• Show different color upon their size
• strong, Hard, and ductile

3. Optical Properties:
Depends on the size of nanomaterials
Light absorption/scattering change with the size of materials-
 < 20nm - Adsorption
 >100nm - Scattering
# Nanoparticles show variation of color upon their size-
• Bulk level - Opaque
• Nanoscale – Transparent
e.g. Copper, silicon
In case of Gold-
• 50nm particles show green in color
• 100nm particles show orange
• >100nm show yellow in color
Gold color in bulk level Gold color in Nano scale

4. Electrical Properties:
Electrical conductivity is altered when it is reduced
to nano size
e.g.
In ceramics,
• Electrical conductivity Nanoparticle size
In metals,
• Electrical conductivity Nanoparticle size
Electrical properties changes with nano particles size
and there are 4 case may be work-
 Surface structure
 Change of electronic structure
 Quantum transport
 Effect of microstructure

5. Mechanical Properties:
Strength, Plasticity, Hardness, Toughness, Ductility, Rigidity
#Nanomaterials shows excellent mechanical properties
due to the volume, surface and quantum effect of Nanoparticles
#Addition, the amount, ratio, and nanoparticle size have a certain
impact on the mechanical properties of nanocomposites
e.g.
The fracture toughness, flexural strength, and hardness
of a cermet composite can be better promoted by
adding nano-TiN than by adding nano-Al2O3 to the matrix
Nanomaterials Size Mechanical properties

6. Magnetic Properties:
 Magnetic nanoparticles (range in 1nm-100nm)
can display superparamagnetic properties. It may
Increase by adding external magnet.
Magnetic nanoparticles
 Nanomaterials are more magnetic than
bulk martials. Even non-magnetic
solid becomes magnetic when
reduced to nanoscale
Magnetic properties nanoparticles
 Example-
Na, k behaves as paramagnetic at bulk
but ferromagnetic at the nano-scale
Again,
Fe, Co, Ni, show ferromagnetic behavior
at bulk whereas superparamagnetic at
the nano size.

7. Chemical Properties:
Melting Points
 Nanoparticles has usually low melting point and reduced lattice constant.
Due to-
Change of Surface energy to Volume energy ratio
 Decrease the size of
nanoparticles then the melting
Point decreases. Surface
energy increases with
the increase of Surface area.
Size effect of nanoparticles
 Melting point may be lower
or higher for nanoparticles,
depending on the strength of
the interaction between the
particles and matrix.

8. Reactivity & Stability
More reactive than bulk materials because of
high surface area/surface energy. When we break
the bond to make nano-size, it get high surface energy.
Surface area Size of particles
 Reactivity Surface area
Size and surface area comparison
Nanomaterials are extensively
Unstable.
Reactivity Stability

9. Size effect of Nanomaterials
 Surface effect
 Quantum Confinement effect(Unique identity of nanomaterials.)
R Eg

10. Deviation of properties
with the size of particles:
Particles Bulk level Nano level
Copper Opaque Transparent
Platinum Inert Catalytic
Aluminum Stable Combustible
Gold Solid Liquid
Silicon Insulator Conductor

11. Thank You…..