This is very short introduction about ferrites, curie temperature and curie weiss law.

1. Curie temperature of
Ferrites
• Name- Ashutosh Tiwari (M.Sc. Physics 2nd year)
• Subject – Material science lab
Submitted to Dr. R.S. Gedam Sir

2. The magnetic behavior of materials can be classified into the following
five major groups:
1. Diamagnetism
2. Paramagnetism
3. Ferromagnetism
4. Ferrimagnetism or Ferrites*
5. Antiferromagnetism

3. What is ferrites ??
Ferrite is ceremic like material with magnetic properties and which is
used in high frequency electrical components.
Ferrite term is used to describe class of magnetic oxide compound that
contain iron oxide as main principle component.
The general chemical composition MO.Fe2O3, where M is a divalent
metal such as Mn, Mg, Fe, Zn, Ni, Cd, etc.

4. • The general chemical composition of ferrite 𝑀+2 𝑂−2. 𝐹𝑒2
+3
𝑂3
−2
, where
M is a divalent metal such as Mn, Mg, Fe, Zn, Ni, Cd, etc.
Crystal
structure of
ferrite

5. B-H Curve hysteresis :

6. Types of
ferrites :
• Soft ferrite : Low coercivity means the material magnetization can easily reverse direction
without dissipating much enegy(Hysteresis loss) while high resistivity prevent eddy current
losses.
• Hard ferrite : High coercivity means material resist to demagnetized as in permanent
magnets (ferromagnets). Due to high magnetic permeability these are called Ceramic magnet.

7. Curie
Temperature
• Curie point, also called Curie Temperature, temperature at which certain magnetic
materials undergo a sharp change in their magnetic properties.
• This temperature is named for the French physicist Pierre Curie, who in 1895
discovered the laws that relate some magnetic properties to change in temperature.
• At low temperatures, magnetic dipoles are aligned. Above the curie point, random
thermal motions nudge dipoles out of alignments.

8. 𝑇𝐶 for different materials:

9. Susceptibility, 𝜒 =
𝐶
𝑇−𝑇 𝐶
=
𝑀
𝐻
Property Diamagnetic paramagnetic ferromagnetic
𝜒 𝜒<0
(negative)
𝜒 does not depend on
temperature
𝜒 ≥ 0
(positive but low)
𝜒 =
𝐶
𝑇
𝜒 ≫ 0
(positive and high)
𝜒 =
𝐶
𝑇−𝑇 𝐶

11. Thank you …