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Dr. Saad B. H. FaridDepartment of Materials EngineeringUniversity of Technology

ENGINEERING MATERIALSINTHEFIELDOF

TELECOMMUNICATION

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Electronic Elements for Telecommunication

Magnetic cores

A magnetic core is a piece of magneticmaterial with a high permeability (thedegree of magnetization of a material inresponse to a magnetic field)used to confine and guide magneticfields in electrical, electromechanicaland magnetic devicessuch as electromagnets, transformers,electric motors, inductors and magnetic

assemblies.

FERRITES

Barium Ferrite and derivativesLead Ferrite and derivativesFerrite PZT and derivatives

Mn Ferrites and derivativesNickel Ferrites and Derivatives

Applications Ferrite characteristics

Filters Low loss, magnetic stability, high permeability

Signal transformers High saturation flux density, high permeability

Power conversion transformers High saturation flux density, low power loss

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http://www.ferrite-cores.net/

Manganese-Zinc FerriteNickel-Zinc ferrite

ISO-9001, ISO-14001

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Typical Physical Properties

Dielectric constantMn-Zn ferrite 240 to 300Ni-Zn ferrite 10 to 13

Specific heat 800 (J/kg K)Thermal conductivity 1 to 5 (W/m K)

Linear thermal expansion coefficient 1.2106 (1/K)

Vickers hardness 550

Tensile strength 2 to 5107 (N/m2)

Bending strength (50mm span) 9.8107 (N/m2)

Youngs modulus 1.21011 (N/m2)

Dielectric and Magnetic Properties

Tailored By DesignTailored by Materials

Candidate MaterialsCandidate Processes

Advantages of Nano-Materials

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Mn FerriteViaProcess routes

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The effect of the different preparation methods on the particle size,lattice parameter (a)FCC Structure,

X-ray density (Dx),

porosity (P%)and Curie temperature (TC)

Preparationmethod

Particlesize (nm)

Latticeparameter a (A)

Dx(g/cm3)

P% TC (K)

S.Ceramic 154.1 8.5621 4.964 2.84 693

Solgel 113.4 8.5372 4.972 6.84 653

Co-ppt 72.5 8.5213 4.948 3.73 513

Flash 40.7 8.5132 4.962 3.19 623

Citrate 14.1 8.4625 5.051 8.57 713

Other effective parametersCrystal defectsCrystallite sizeCrystal/Grain Boundary ChemistryGrain Shape

Porosity Shape and Distribution

All active Fields of R&D Jump of properties with

Nano-technology

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The molar magnetic susceptibility (M) for differentpreparation methods

A few tens of nanometers can be considered as single domains and,hence, display properties markedly different from the bulk. One of theinteresting features of nano-size magnetic materials is the presence of amagnetic relaxation process that is due to the thermal effect and theexistence of energy barriers separating the local minima for different

equilibrium states of the system. As a result, the magnetic behavior of asmall particle depends on its relaxation time ( ). When is smaller than

the experimental time, the magnetization vector is seen to change quicklybetween different states, i.e. the system is in a super-paramagnetic state.

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State of the art, International

State of the art, IRAQConclusions

Wide open Materials R&D and Product DesignEstablishing Material Engineering for TelecommunicationEconomic BenefitsNational Security A

B C

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Comparison between the wet methods and the conventional ceramic method

No Wet methods Conventional ceramic method

1 Chemical of mixing of the raw

materials results in ahomogeneous mixture.

Mechanical mixing of raw materials; difficult

to get complete homogeneity.

2 Single phase ferrite formation andsmall grain size can be easily

obtained.

Possibility of some phase segregation

cannot be ruled out

3 No impurity pick-up or material lossduring processing.

There is a possibility of impurity pick-ups andloss of material during the grinding process.

4 Lower temperature processing,shorter sintering duration requiredand no specific heating and or

cooling rate is required.

Processing requires a higher temperatureand longer durations due to lower reactivityof the starting oxides, the heating and/or

cooling rates control the particle size.5 Simple methods and economical. Cumbersome and expensive methods.

6 The raw materials are in the formnitrate, citrate, acetates and

chlorides.

The raw materials are always in the form ofoxides or carbonates

7 Increased reactivity of oxidesobtained on thermal decomposition. Starting oxides are of low reactivity.