Top Banner
Comparison of B-versus-H behaviors for ferromagnetic/ferrimagnetic and diamagnetic/ paramagnetic materials
11
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Mag-1

Comparison of B-versus-H behaviors for ferromagnetic/ferrimagnetic and diamagnetic/ paramagnetic materials

Page 2: Mag-1

THE INFLUENCE OF TEMPERATURE ON MAGNETIC BEHAVIOR

• The saturation magnetization is a maximum at 0 K

• Curie temperature, Tc, the saturation magnetization diminishes

gradually and then abruptly drops to zero

• temperatures above Tc both ferromagnetic and ferrimagnetic

materials are paramagnetic

• for iron, cobalt, nickel, and Fe3O4, the respective values are 768,

1120, 335, and 585oC

Page 3: Mag-1

• Antiferromagnetism is also affected by temperature; this

behavior vanishes at what is called the Néel temperature.

• At temperatures above this point, antiferromagnetic

materials also become paramagnetic

Page 4: Mag-1

DOMAINS

Page 5: Mag-1

Magnetisation Curve

Page 6: Mag-1

Essential Characteristics of a Permanent Magnetic Material After it has been Magnetised

1 Coercive Force

2 Residual Magnetism or Remanence

3 Energy Product Value

Page 7: Mag-1

1 Coercive Force : It is a measure of materials

resistance to demagnetisation by electrical means

2 Residual Magnetism or Remanence : It relates to the

intensity of magnetism remaining in the magnet after

the magnetic field has been switched off

3 Energy Product Value: It is virtually the quantity of

energy stored in the magnet following magnetisation

It is derived from the demagnetisation curve RC

Page 8: Mag-1

HYSTERESIS

This lagging of the flux

density B with respect to

the magnetising field H is

called Hysteresis

OR represents remanent

magnetism or remanence, Br

Page 9: Mag-1

SOFT & HARD MAGNETIC MATERIALS

Page 10: Mag-1

HARD MAGNETIC MATERIALS

Page 11: Mag-1

PROPERTIES OF SOFT AND HARD MAGNETIC MATERIALSSOFT MAGNETIC MATERIALS

Have High Permeability

Magnetic Energy Stored is not High

Have Negligible Coercive Force

Have low Remanance

Have low Resistivity and low Hysteresis loss

HARD MAGNETIC MATERIALS

Possess High Value of Energy Product i.e. BH value

Have High Retentivity and High Coercivity

Have strong Magnetic Reluctance

Have Hysteresis Loop Rectangular in Shape

Have Low Initial Permeability and High Hysteresis Energy Loss