1. Electrical and Electronics Engineering Materials
Electrical and Electronics Engineering Materials Electrical Engineering Third Semester

2. Detailed Contents Classifications of materials
Properties of conductors
Properties of semiconductors
Properties of insulators
Classification based on atomic structure and energy band
Copper and its properties
Aluminium and its properties
High resistivity materials
Superconductors
Semiconductors

3. Classification of materials
Classification of Conducting ,semi conducting and insulating materials based on atomic structure
Classification of Conducting ,semi conducting and insulating materials based on energy bands
A conductor of electricity is a material or substance which allows to flow of electric current when subjected to a potential difference Gold ,silver, copper and Aluminium are conductors.
A material or an object that does not easily allow heat, electricity, light, or sound to pass through it. Air, cloth and rubber are good electrical insulators
Semiconductor has a conductivity between that of an insulator and conductor example silicon and germanium

4. Properties of conductors
Resistance of conductor is very low or negligible.
The electric filed inside the conductor is zero
The charge density inside the conductor is zero
High conductivity
Casted, forged, rolled, drawn and machined
Malleable and Ductile
Positive temperature coefficient of resistance.

5. Properties of Semiconductor
Conductivity lies between conductor and insulator.
They are negative temperature coefficients of resistance.
Resistivity is high
Adding of impurity result in increased conductivity.
Small forbidden energy band of 1ev approx.

6. Properties of Insulators
High resistance
High dielectric strength
They are rigid , tough and strong
Low permittivity
Low dissipation factor
Least thermal expansion
High thermal strength

7. Classification based on atomic structure

8. Classification based on energy bands

9. Classification of conducting material as low resistivity and high resistivity materials
Low resistance materials Copper, Aluminium, steel, Silver, Gold, Platinum , copper alloys Brass, Bronze.
High resistivity materials manganin, constantan, Nichrome, mercury, platinum, carbon and tungsten

10. Copper and its properties
A good electrical conductor
A good thermal conductor
Corrosion resistant
Antibacterial
Easily joined
Ductile
Tough
Non magnetic
Easy to alloy
Recyclable
Catalytic

11. Properties of Aluminium
It is silver- white in colour
It posses high ductility
It has high thermal and electrical conductivity
It has high contact resistance
High reflectivity for light rays
It can be rolled into thin sheets and drawn into wires

12. Copper alloys Brass, Bronze
An alloy is a combination of metals
Brass and bronze are both alloys of copper -- that is, they are ``solid solutions," or mixtures of copper with another metal.
The main difference between brasses and bronzes is that brass is mostly made of copper and zinc while bronze is mostly made of copper and tin.

13. High resistivity material properties
High melting point.
High mechanical strength.
High ductility, so that can be drawn in the form of wire easily.
High corrosion resistance mean free from oxidation.
Low cost.
Long life or durable.
High flexibility.

14. Superconductors and their applications
Superconductivity is a phenomenon of exactly zero electrical resistance when cooled below a characteristic critical temperature
Superconducting magnets are used in MRI (Magnetic Resonance Imaging) which is a way of looking at the soft
Low and high field magnets for Nuclear Magnetic Resonance (NMR) parts of the body.
Industrial magnets for materials magnetic separation

15. Semiconductors
A solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects
Most common materials commercially used as semiconductors are germanium (Ge) and silicon (Si) because of their property to withstand high temperature
Semiconductors show negative temperature coefficient
Semiconductor in its pure form is called as intrinsic semiconductor
Impure semiconductors are called extrinsic semiconductors

16. Extrinsic Semiconductors Types
N-type and P-type semiconductors
N-type semiconductor majority carriers are electrons and minority carriers are holes. It is formed by adding pentavalent impurity e.g. P. As, Sb
P-type semiconductor majority carriers are holes, and minority carriers are electrons. These are formed by adding trivalent impurity e.g. B, Al Ba

17. Thanks