THAPAR UNIVERSITY PATIALA

M TECH 2nd sem. 2012

MATERIALS AND METALLURGICAL

ANOOP PRATAP SINGH

ROLL NO 601102002

Under the supervision

Dr. PUNEET SHARMA

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“HEXA-FERRITE THIN FILM

PREPARED BY SOL-GEL

METHOD”

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Hexa-ferrites

The Hexa-Ferrites are also assigned as Hard because the Magnetization directions not change easily.

Formula M (Fe12O19)

Where M =Ba, Sr, Pb

It has one c- axis which easily magnetized

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M -type (BaFe12O19 )

U-type (Ba4Me2Fe36O60)

W- type (BaMe2Fe16O27)

X- type (Ba2Me2Fe28O46)

Y- type (Ba2Me2Fe12O22)

Z- type (Ba3Me2Fe24O41)

Type of Hexa-ferrites

Main type

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Physical properties of Ba, Sr, and Pb Hexa-ferrite

  Lattice constant (a)

Lattice constant (c)

Mass density(gm/cm3)

µ0.MS(RT)

(T)

Tc(K)

BaM 0.589 2.32 5.3 0.48 740

SrM 0.587 2.31 5.11 .043 745

PbM 0.588 2.30 5.68 0.43 725

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Processing of Hexa-Ferrites

Chemical Co-precipitation

Method

Self Propagating High

Temperature Synthesis,

Salt Melting Method,

Ball Milling,

Solid State Method, and

Sol-Gel Method

Sol-Gel-The Sol-Gel process involves the

transition of a solution system

from a liquid "Sol" (mostly

colloidal) into a solid "Gel" phase.

The Sol-Gel Synthesis is to “dissolve” the compound in a liquid in order to bring it back as a solid in a controlled manner

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Why

Sol

-Gel

??

Advantages of Sol- Gel method To provide corrosion protection Produced high purity productsCan have low temperature

sintering capability, usually 200-600°C.

Economically it is cheapLow processing Temperature Good shape abilityGood homogeneity Processing

Disadvantage of Sol -Gel Method High cost of raw materialLarge shrinkage damage

processingResidual fine pores and

hydroxylsHealth , hazards of organic

solutionsEasily cracking during the

drying stageTake Large processing times 

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Sol –Gel Formation

Sol Formation Gel Formation

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Deposition Method of thin films

Physical method

Thermal EvaporatorSputtering Pulse Laser

DepositionsArc DepositionsElectro-Spray

Deposition

Chemical methods

Electro-PlatingChemical Solution

Deposition Chemical-Vapor DepositionAtomic Layer DepositionsSpin Coating/Spin Casting

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Spin CoatingSol-Gel precursor deposited onto a smooth flat sub-strate that

is spun at a high velocity to centrifugally spread the solution

over the substrate

The speed of spin and the viscosity of sol to determine the

thickness of the deposited film

If process of spread repeated then thickness of film against

increase

Thermal treatment given to crystalline the amorphous spin

coated film such crystalline film can exhibit certain preferred

orientation as a single crystal structure.

To create thin films with thicknesses below 10 nm

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Spin Coating

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