Properties at Nanoscale

As particle sizes and layer thicknesses approach the nm size scale, special properties begin to emerge. For example as particles get smaller in diameter a greater percentage of the atoms in the particle reside on the surface of the particle as shown below. Smaller than 10nm, the number of surface atoms dramatically increases, increasing the reactivity of these particles. At below 2nm diameter 50% of the atoms in the particle, and hence have more degree of freedom because they have fewer constraints and they become more active additionally as the particle become smaller, their relative surface areas increases, again making them more chemically active. When heated, the atoms in a crystal begin to oscillate with increasing degree of amplitude, when the temperature is hot enough to increase the amplitude of atomic oscillation to break the crystal structure, the material will spontaneously melt. In nanoscale particles, the surface atoms are not as strongly bound as core atoms. When most of the atoms in the particle reside on the surface, the melting point of the particle can be few nm gold particle can melt at room temperature. Following are examples of the special properties of nanomaterials.
1. By varying the size of the materials to nanoscale the emission wavelength can be adjusted to any color. This technology can be used in dyes, paint display and chemical sensitive, sunscreen for example Zno and Tio2 – both metal oxide in sunscreen because they absorb UV that dangerous to skin Tio2 (50nm) particle absorb high energy UV radiation and transparent to visible light.
 2. By varying the size of the materials to nanoscale the emission wavelength can be adjusted to any color from blue up through IR. This technology can be used in dye, paint, display and sunscreen. NOTE: Particle of TiO2 and ZnO both metal oxides used in su7nscreen because they absorb UV radiation that damages skin. TiO2 (50 nm) particle absorb high energy UV radiation and are transparent to visible light. Whereas normal sized TiO2 turns skin white.
3. Nanoscale components have very high surface area to volume ratio making them ideal for use in composite material, chemical energy storage.
 4. At nanoscale gravitational force diminishes whereas electrostatic force is prominent.
5. At nanoscale tensile strength is more for example carbon nanotube 100 times stronger than steel.
 6. At nanoscale material like Al become combustible.
7. At nano dimension opaque metal like copper become transparent.
8. Noble metals like Au, Hg become more active.
9. Nano structured macroscopic systems which have higher density can be employed in smaller and faster circuit with reduced power consumption.
10. At nanoscale metals like gold, silver etc. shows excellent anti microbial activity. Note: catheters are usually soaked with Ag nano particle which helps in destroying infection producing bacteria/germs.