A complete Detail on Magnetism which gives a broad idea about the topic

1. Presented by :
Arvind Singh Heer
MSc-I
(Sem-II)
Inorganic Chemistry
MITHIBAI COLLEGE
MAGNETISM

2. CONTENT
 INTRODUCTION
 TYPES OF MAGNETISM
 CURIE AND CURIE WEISS LAWS
 MAGNECTIC SUSCEPTIBILITY

3. INTRODUCTION
Magnetism is a property of materials
that respond to an applied magnetic
field that cause the material to be
either attracted or repelled.

4. TYPES OF MAGNETISM
Paramagnetic
Ferromagnetic
Antiferromagnetic
ferrimagnetic

5. Diamagnetic
 Feebly repelled by the magnetic fields.
Non-metallic elements (excepts O2, S)
inert gases and species with paired
electrons are diamagnetic
 All paired electrons
 TiO2, V2O5,NaCl, C6H6(benzene)
 Insulator

6. Paramagnetic
 Attracted by the magnetic field due to the
presence of permanent magnetic dipoles
(unpaired electrons). In magnetic field,
these tend to orient themselves parallel to
the direction of the field and thus, produce
magnetism in the substances.
 At least one unpaired electron
 O2, Cu2+, Fe3+, TiO, Ti2O3, VO, VO2, CuO
 Electronic appliances

7. Ferromagnetic
 Permanent magnetism even in the
absence of magnetic field, Above a
temperature called Curie temperature,
there is no ferromagnetism.
 Dipoles are aligned in the same direction
 Fe, Ni, Co, CrO2
 CrO2 is used in audio and video tapes

8. Antiferromagnetic
 This arises when the dipole alignment is
zero due to equal and opposite alignment.
 MnO, MnO2,Mn2O, FeO, Fe2O3; NiO,
Cr2O3, CoO, Co3O4,

9. CURIE LAW
This law indicates that the susceptibility of paramagnetic
materials is inversely proportional to their temperature, i.e.
that materials become more magnetic at lower temperatures.
The mathematical expression is:
M- magnetisation
X- magnetic susceptibility
H- magnetic field
T- absolute temperature
C- curie’s constant

10. CURIE & WEISS LAW
The temperature dependence of which
requires an amended version of Curie's
law, known as the Curie–Weiss law:
θ - Weiss constant

11. MAGNETIC SUSCEPTIBILITY
Magnetic susceptibility is related to the
force experienced by a substance in a
magnetic field
The magnetic moment is calculated from
the magnetic susceptibility, since the
magnetic
moment is not measured directly
The magnetic susceptibility per unit volume
is
K = I/H

12.  Generally, it is more convenient to use mass
units,therefore the mass or gram susceptibility is
defined as:
xg =k/d
where d is the density of the solid.
 The molar susceptibility is the mass susceptibility
multiplied by the formula weight.
xm= xg(F.W. in g mol ) -1

13.  In the Faraday balance the field is inhomogeneous.
 The pole pieces of the magnet are so shaped that there
is region in which the product of the field strength and
field gradient in the z direction is constant.
 The sample is placed in this region.
 The force in this case is independent of the packing of
the sample and depends only on the total mass of the
material present.
 The method is sensitive and highly reproducible and
can be applied to single crystals
 The force is measured as a weight change, using a
torsion balance.

14. Magnetic behavior may be distinguished by the values of χ and
μ and by their temperature and field dependence
1. Positive vs. negative value: only diamagnetic materials
show negative χ
2. Absolute value: ferromagnetic materials show huge
positivevalue
3. Temerature dependence: diamagnetism is not temp.
dependence,
antiferromagentic materials increase with increasing
temp, and
para- and ferromagnetic materials decrease with
increasing temp

15. REFERENCE
Chemical Structure and Bonding
H.B. Gray
R.L. Dekock
-THANK YOU