Distinction Between Nano Particles, Molecules and Bulk Materials

DISTINCTION BETWEEN NANO PARTICLES, MOLECULES AND BULK MATERIALS

1. The size of nano particles are less than 100 nm in diameter, molecules are in the range of picometers, but bulk materials are larger in micron size.

2. Molecule is a collection of atoms, nano particles are collection of few molecules that is less than 100 nm but bulk materials contains thousands of molecules.

3. Surface area of nano particles is more than the bulk materials.

4. Hardness of nano materials is 5 times more than the bulk materials.

5. Strength of nano materials is 3 - 10 times higher than the bulk materials.

6. Nano particles possesses size dependent properties, but bulk materials possess constant physical properties.

7. Corrosion resistance is more than the bulk materials, hence localised corrosion in nano materials is stopped.

8. Behavior of bulk materials can be changed, but cannot enter inside the nano particles.

9. Nano particles, due to its size, possess unexpected optical (visible) properties.

Examples

(i) Gold nano particles appear deep red to black colour in solution compared to yellow colour with Gold.

(ii) ZnO nanoparticles possesses superior UV blocking property compared to bulk material.

(iii) Absorption of solar radiation in photovoltaic cell containing nano particles are higher than the film (bulk material).

10. Nano particles possesses lower melting point than the bulk materials.

Example

Gold nanoparticles melt at lower temperature (300°C) for 2.5 nm, but Gold slab melts at 1064°C.

11. Sintering of nano particles takes place at lower temperature and in short time than the bulk materials.

12. Electrical properties, resistivity of nano particles are increased by 3 times.

13. Suspension of nano particles is possible, because nano particles possess high surface area, but bulk materials cannot.

14. The wear resistance of nano particles are 170 times higher than the bulk materials.

Table 2.1 Comparison of atom/molecule, nano particles/cluster, bulk materials