5th_SEM_EM_DVS_Unit_1.pdf5th sem Electrical machine notes 1st unit

5th sem Electrical machine notes 1st unit

1. Subject Name: Electrical Materials
Subject Code: 5EE3-01
Credit: 2 Max. Marks: 100(IA:30, ETE:70)
2L+0T+0P End Term Exam: 3 Hours
SubjectTeacherName: Dr.VirendraSharma
Name of Department: Electrical Engineering
UNIT-1

2. SyllabusofEM:SubjectName:5EE3-01:ELECTRICALMATERIALS
Credit:2;2L+0T+0P; Max.Marks:100(IA:30,ETE:70); EndTermExam:3Hours
Sr. No. Contents Hours
1. Introduction:Objective,scopeandoutcomeofthecourse. 01
2. ElementaryMaterialsScienceConceptsBondingandtypesofsolids,Crystallinestateandtheir
defects,Classicaltheoryofelectricalandthermalconductioninsolids,temperature
dependenceofresistivity,skineffect,Halleffect.
05
3. DielectricPropertiesofInsulatorsinStaticandAlternatingfield:Dielectricconstantofmono-
atomicgases,poly-atomicmoleculesandsolids,Internalfieldinsolidsandliquids,Propertiesof
Ferro-Electricmaterials,Polarization,Piezoelectricity,FrequencydependenceofElectronicand
IonicPolarizability,Complexdielectricconstantofnon-dipolarsolids,dielectriclosses.
08
4. MagneticPropertiesandSuperconductivityMagnetizationofmatter,MagneticMaterial
Classification,FerromagneticOrigin,Curie-WeissLaw,SoftandHardMagneticMaterials,
Superconductivityanditsorigin,ZeroresistanceandMeissnerEffect,criticalcurrentdensity.
05
5. ConductivityofmetalsOhm’slawandrelaxationtimeofelectrons,collisiontimeandmeanfree
path,electronscatteringandresistivityofmetals.
04
6. SemiconductorMaterials:Classificationofsemiconductors,semiconductorconductivity,
temperaturedependence,Carrierdensityandenergygap,TrendsinmaterialsusedinElectrical
Equipment.
04
Total27

3. SyllabusofEM:SubjectName:5EE3-01:ELECTRICALMATERIALS
1.ElectricalandElectronicsEngineeringMaterials,JBGupta
2.A Course in Electrical Engineering Materials
Author :R.K. Rajput, Edition :First Edition, 2009, ISBN
:9788131807040, JBA Book Code :52675
3.C S Indulkar, S. Chand Publishing, 2008 -Technology & Engineering-
468 pages
A Textbook for the students of B.Sc.(Engg.), B.E., B.Tech., AMIE and
Diploma Courses. A new chapter on ""Semiconductor Fabrication
Technology and Miscellaneous Semiconductor Devices"" had been
included and additional self-assessment questions with answers and
additional worked examples had been provided at the end of the
BOOK.
Total27

4. ElementaryMaterialsScienceConcepts:(1)
ElementaryMaterialsSciencefocusesonunderstandingthefundamental
propertiesandbehaviorsofmaterials.Herearesomekeyconcepts:
1.AtomicStructureandBonding:
AtomsandElements:Thebasicbuildingblocksofmaterials,eachelement
havingauniqueatomicstructure.
BondingTypes:
IonicBonding:Transferofelectronsbetweenatoms.
CovalentBonding:Sharingofelectronsbetweenatoms.
MetallicBonding:Electronsarefreetomovewithinametallattice.
VanderWaalsForces:Weakattractionsbetweenmolecules.
2.CrystallineandAmorphousStructures:
CrystalLattices:Regular,repeatingarrangementofatomsinamaterial,
formingstructureslikeBody-CenteredCubic(BCC),Face-CenteredCubic(FCC),
andHexagonalClose-Packed(HCP).
AmorphousMaterials:Lackalong-rangeorderintheiratomicarrangement,
likeglassandsomepolymers.
UNIT-1

5. ElementaryMaterialsScienceConcepts:
3.DefectsinSolids:
PointDefects:Vacancies(missingatoms),interstitials(extraatomsinthelattice),and
substitutionaldefects(foreignatomsreplacinghostatoms).
LineDefects(Dislocations):Imperfectionsinthecrystalstructurethataffect
mechanicalproperties.
SurfaceDefects:Grainboundaries,wheredifferentcrystallineregionsmeet.
4.PhaseDiagrams:
Phases:Differentformsofamaterial,suchassolid,liquid,andgas.
PhaseDiagrams:Graphsshowingthestablephasesofamaterialatdifferent
temperaturesandpressures.
Eutectic,Peritectic,andSolidSolutions:Commonfeaturesinphasediagramsthat
describehowdifferentphasescoexistortransform.
5.MechanicalProperties:
StressandStrain:Stressistheforceappliedperunitarea,andstrainisthe
deformationcausedbystress.
ElasticityandPlasticity:Elasticmaterialsreturntotheiroriginalshapeafterstressis
removed;plasticmaterialsdonot.

6. ElementaryMaterialsScienceConcepts:
Hardness,Toughness,andDuctility:Measuresofamaterial'sresistanceto
deformation,fracture,andabilitytostretch.
6.ThermalProperties:
HeatCapacity:Theamountofheatrequiredtoraisethetemperatureofamaterial.
ThermalExpansion:Howmuchamaterialexpandswhenheated.
ThermalConductivity:Theabilityofamaterialtoconductheat.
7.ElectricalandMagneticProperties:
Conductivity:Theabilityofamaterialtoconductelectricity.
Semiconductors,Insulators,andConductors:Materialsclassifiedbasedontheir
abilitytoconductelectricity.
MagneticProperties:Howmaterialsrespondtomagneticfields,including
ferromagnetism,Paramagnetism,anddiamagnetism.
8.OpticalProperties:
RefractiveIndex:Ameasureofhowmuchlightisbentwhenenteringamaterial.
AbsorptionandTransmission:Howmaterialsabsorbandtransmitlight.
Luminescence:Emissionoflightbyamaterial,suchasfluorescenceand
phosphorescence.

7. ElementaryMaterialsScienceConcepts:
9.CorrosionandDegradation:
Oxidation:Acommonformofcorrosionwherematerials
reactwithoxygen.
ElectrochemicalCorrosion:
Degradationofmaterialsthroughelectrochemicalreactions,
ofteninvolvingwaterandsalts.
Theseconceptsformthefoundationofmaterialsscience
andareessentialforunderstandinghowmaterialsbehave
andhowtheycanbemanipulatedforvariousapplications.

8. BondingandTypesofSolids:(Topic-2)
Thepropertiesofsolidsarelargelydeterminedbythetypesofbondsthatholdtheir
atomsormoleculestogether.Thereareseveraltypesofbondinginsolids:
1.IonicBonding:
Mechanism:Ionicbondsformbetweenatomswithsignificantlydifferent
electronegativities,typicallybetweenmetalsandnon-metals.Themetalatom
donatesoneormoreelectronstothenon-metalatom,resultinginpositively
chargedcationsandnegativelychargedanions.
Characteristics:
Strongelectrostaticattractionbetweenions.
Highmeltingandboilingpoints.
Generally,poorelectricalconductivityinthesolidstatebutgoodconductivityin
moltenordissolvedstates.
Examples:Sodiumchloride(NaCl),magnesiumoxide(MgO).
2.CovalentBonding:
Mechanism:Covalentbondsformwhentwoatomsshareoneormorepairsof
electrons.Thistypeofbondingoccursprimarilybetweennon-metalatoms.
Characteristics:

9. BondingandTypesofSolids:
Characteristics:
Strongdirectionalbonds.
Highmeltingandboilingpoints,thoughlowerthanioniccompounds.
Poorelectricalconductivity,astherearenofreeelectronsorions.
Examples:Diamond(C),siliconcarbide(SiC),water(H₂O).
3.MetallicBonding:
Mechanism:Inmetallicbonding,atomsinametallatticereleasesomeoftheir
electronstoforma"seaofelectrons"thatarefreetomovethroughoutthe
structure.Thesedelocalizedelectronsallowmetalstoconductelectricity.
Characteristics:
Highelectricalandthermalconductivity.
Malleabilityandductility.
Generallyhighmeltingandboilingpoints.
Examples:Iron(Fe),aluminum(Al),copper(Cu).
4.VanderWaalsBonding(LondonDispersionForces):
Mechanism:VanderWaalsforcesareweak,non-covalentinteractionsbetween
molecules.Theyariseduetotemporarydipolescreatedbyfluctuationsinelectron
distribution.

10. BondingandTypesofSolids:
Characteristics:
Verylowmeltingandboilingpoints.
Usuallyfoundinmolecularsolidsandinertgases.
Weakandeasilydisruptedbythermalenergy.
Examples:Solidnoblegases(e.g.,Argon,Ar),molecularsolidslikeiodine(I₂).
5.HydrogenBonding:
Mechanism:Hydrogenbondingisaspecifictypeofdipole-dipoleinteractionthat
occurswhenhydrogeniscovalentlybondedtoahighlyelectronegativeatom(e.g.,
oxygen,nitrogen,orfluorine)andisattractedtoanotherelectronegativeatomina
neighboringmolecule.
Characteristics:
HighermeltingandboilingpointscomparedtoothervanderWaalsinteractions.
Significantinbiologicalmolecules(e.g.,DNA,proteins)andwater.
Examples:Water(H₂O),ammonia(NH₃),hydrogenfluoride(HF).
TypesofSolids
Basedonthebondingandstructuralorganizationoftheirconstituentparticles,
solidscanbeclassifiedintodifferenttypes:

11. BondingandTypesofSolids:
1.IonicSolids:
Constituents:Ions(cationsandanions).
Bonding:Ionicbonding.
Properties:
Hardandbrittle.
Highmeltingandboilingpoints.
Poorelectricalconductivityinthesolidstatebutconductivewhenmoltenor
dissolved.
Examples:Sodiumchloride(NaCl),calciumfluoride(CaF₂).
2.Covalent(Network)Solids:
Constituents:Atoms.
Bonding:Covalentbondingthroughouttheentirestructure.
Properties:
Veryhardandstrong.
Highmeltingpoints.
Poorelectricalconductivity.
Examples:Diamond(C),silicondioxide(SiO₂).

12. BondingandTypesofSolids:
3.MetallicSolids:
Constituents:Metalatoms.
Bonding:Metallicbonding.
Properties:
Goodelectricalandthermalconductivity.
Malleableandductile.
Rangeofmeltingpoints,generallyhigh.
Examples:Iron(Fe),copper(Cu),aluminum(Al).
4.MolecularSolids:
Constituents:Molecules.
Bonding:VanderWaalsforcesorhydrogenbonding.
Properties:
Lowmeltingandboilingpoints.
Usuallysoftandbrittle.
Poorelectricalconductivity.
Examples:Ice(H₂O),dryice(solidCO₂),iodine(I₂).

13. BondingandTypesofSolids:
5.AmorphousSolids:
Constituents:Atomsormoleculesnotarrangedinalong-range
order.
Bonding:Varies(canincludecovalent,ionic,metallic,orvander
Waalsbonding).
Properties:
Lackadefinitegeometricshape.
Donothaveasharpmeltingpoint.
Canbebrittle.
Examples:Glass,rubber,plastic.
Eachtypeofsolidhasdistinctphysicalpropertiesbasedonthe
natureofitsbondingandstructure,influencingitsapplications
andbehaviorunderdifferentconditions.

14. CrystallineStateandTheirDefects:(Topic-3)
Thecrystallinestatereferstothehighlyorderedstructureofamaterialinwhich
atoms,ions,ormoleculesarearrangedinarepeatingpatternextendinginallthree
spatialdimensions.Thisregulararrangementofparticlesresultsintheformationof
acrystallattice,whichisthefundamentalcharacteristicofacrystallinematerial.
KeyFeaturesoftheCrystallineState:
LatticeStructure:Theatomsormoleculesinacrystallinesolidarearrangedina
specificandrepeatingpatternknownasacrystallattice.Eachpointinthelattice,
calledalatticepoint,hasthesameenvironmentaseveryotherpoint.
UnitCell:Thesmallestrepeatingunitinacrystallatticeiscalledtheunitcell.The
entirecrystalstructurecanbegeneratedbyrepeatingtheunitcellinthree
dimensions.
Symmetry:Crystalsexhibitvarioustypesofsymmetry,suchasrotationalsymmetry,
reflectionsymmetry,andtranslationalsymmetry,whichcontributetotheiroverall
geometricregularity.
Anisotropy:Crystallinesolidsoftenexhibitanisotropicproperties,meaningthat
theirphysicalproperties,suchaselectricalconductivity,refractiveindex,and
thermalexpansion,varydependingonthedirectioninwhichtheyaremeasured.

15. CrystallineStateandTheirDefects:
TypesofCrystallineSolids:
IonicCrystals:Composedofionsarrangedinalatticestructure,heldtogetherby
strongelectrostaticforces(e.g.,sodiumchloride).
CovalentCrystals:Atomsareconnectedbycovalentbondsinanetworkextending
throughoutthematerial(e.g.,diamond,silicon).
MetallicCrystals:Consistofmetalatomssurroundedbyaseaofdelocalized
electrons,allowingforconductivityandmalleability(e.g.,copper,iron).
MolecularCrystals:Moleculesareheldtogetherbyweakerintermolecularforces
suchasvanderWaalsforcesorhydrogenbonds(e.g.,ice,solidCO2).
DefectsinCrystallineSolids:
Defectsinacrystallatticeareimperfectionsthatdisrupttheregulararrangementof
atoms,ions,ormolecules.Thesedefectscansignificantlyinfluencethephysical
propertiesofthematerial.
TypesofDefects:
PointDefects:
Vacancies:Occurwhenanatomorionismissingfromitslatticesite.
InterstitialDefects:Occurwhenanextraatomorionoccupiesaspaceinthe
latticethatisnotnormallyalatticepoint.

16. CrystallineStateandTheirDefects:
SubstitutionalDefects:Occurwhenanatomorioninthelatticeisreplacedbya
differentatomorion.
LineDefects:
Dislocations:Linedefectswhereatomsaremisalignedinthecrystalstructure.
Twomaintypesare:
EdgeDislocations:Extrahalf-planeofatomsisinsertedinthelattice.
ScrewDislocations:Thecrystalplanestwistaroundaline,formingahelical
structure.
SurfaceDefects:
GrainBoundaries:Theinterfaceswherecrystalsofdifferentorientationsmeet
withinamaterial.Theseboundariesdisruptthecontinuityofthelattice.
SurfaceSteps:Occuronthesurfaceofacrystalwhereonepartofthesurfaceis
raisedorloweredrelativetoanother,creatingastep.
VolumeDefects:
Voids:Largerregionswithinthecrystalwhereatomsorionsaremissing,
creatinganemptyspace.

17. CrystallineStateandTheirDefects:
ImpactofDefects:
MechanicalProperties:Defectscanweakenamaterialormakeitmore
ductile,dependingonthetypeandconcentrationofdefects.
ElectricalProperties:Defectscaninfluencetheelectricalconductivity
ofmaterials,particularlyinsemiconductorswherepointdefectscanact
aschargecarriers.
OpticalProperties:Defectscancausevariationsintherefractiveindex
andabsorbance,leadingtochangesincolorortransparency.
Understandingthecrystallinestateanditsdefectsiscrucialinmaterials
science,asitallowsforthemanipulationandenhancementofmaterial
propertiesforvariousapplications.

18. ClassicaltheoryofElectricalandThermalconductioninsolids:(Topic-4)
Theclassicaltheoryofelectricalandthermalconductioninsolidsis
primarilybasedontheDrudemodel,developedbyPaulDrudein1900.
Thismodeldescribesthebehaviorofelectronsinametalasaclassical
gasoffreeparticles,providingaframeworkforunderstandinghow
metalsconductelectricityandheat.
ElectricalConductioninSolids
1.DrudeModel:
ElectronGas:TheDrudemodeltreatstheelectronsinametalasagas
offree,non-interactingparticlesthatmovethroughthelatticeof
positiveions.
MeanFreePath:Electronsundergorandomcollisionswiththeionsin
thelattice.Theaveragedistanceanelectrontravelsbetweencollisions
iscalledthemeanfreepath.

19. ClassicaltheoryofElectricalandThermalconductioninsolids:
Ohm'sLaw:AccordingtotheDrudemodel,whenanelectricfieldisappliedtoa
metal,thefreeelectronsareacceleratedinthedirectionoppositetothefield.
ThisresultsinacurrentdensityJ,whichisproportionaltotheappliedelectricfieldE.
whereσistheelectricalconductivityofthematerial,definedas:
Here,nisthenumberdensityofelectrons,
eisthechargeofanelectron,
τ\tauτistheaveragetimebetweencollisions(relaxationtime),
andmisthemassofanelectron.
2.LimitationsoftheDrudeModel:
TemperatureDependence:TheDrudemodelpredictsthatelectricalconductivity
decreaseswithincreasingtemperatureduetoincreasedscattering,whichis
consistentwithexperimentalobservationsformetals.

20. ClassicaltheoryofElectricalandThermalconductioninsolids:
SpecificHeat:TheDrudemodeloverestimatestheelectronic
contributiontothespecificheatofmetalsbecauseitdoesn'tconsider
thequantumnatureofelectrons.
Electron-ElectronInteractions:Themodelignoresinteractions
betweenelectrons,whichcanbesignificantincertainmaterials.
ThermalConductioninSolids
1.ThermalConductivity(Fourier'sLaw):
HeatFlow:Inasolid,heatisconductedbythetransferofkineticenergy
fromhottertocoolerregions.AccordingtoFourier'slaw,theheatfluxq
isproportionaltothetemperaturegradient∇T.
wherekisthethermalconductivityofthematerial.

21. ClassicaltheoryofElectricalandThermalconductioninsolids:
2.Wiedemann-FranzLaw:
RelationBetweenElectricalandThermalConductivity:TheDrude
modelpredictsarelationshipbetweentheelectricalconductivityσand
thethermalconductivitykofametal,givenbytheWiedemann-Franz
law:
whereListheLorenznumber,andTistheabsolutetemperature.This
lawimpliesthatmetalswithhighelectricalconductivityalsohavehigh
thermalconductivity.
3.LimitationsofClassicalTheory:
Phonons:Theclassicaltheoryonlyconsiderselectroncontributionsto
thermalconductivity.However,innon-metalsandeveninsomemetals
athightemperatures,heatisalsoconductedbylatticevibrations,
knownasphonons.

22. ClassicaltheoryofElectricalandThermalconductioninsolids:
QuantumEffects:Theclassicaltheoryfailstoexplaincertainlow-
temperaturephenomena,suchasthesharpdecreaseinthermal
conductivitywithdecreasingtemperature,whichrequiresquantum
mechanicalexplanations.
SummaryoftheClassicalTheory
ElectricalConduction:BasedontheDrudemodel,whichtreats
electronsasaclassicalgas,predictingelectricalconductivityusing
Ohm'slaw.
ThermalConduction:DescribedbyFourier'slawandrelatedto
electricalconductivitythroughtheWiedemann-Franzlaw.
Limitations:Theclassicaltheoryhassignificantlimitations,especiallyin
explaininglow-temperaturebehaviorandspecificheat,requiring
quantummechanicaltheorieslikethefreeelectronmodelandthe
Blochtheorytoprovideamoreaccuratedescription.

23. ClassicaltheoryofElectricalandThermalconductioninsolids:
Theclassicaltheorieslaidthegroundworkfortheunderstandingof
conductioninsolids,buttheyhavesincebeenrefinedandexpandedby
quantummechanicstomoreaccuratelydescribethebehaviorof
electronsandthermalconductioninmaterials.

24. Temperaturedependenceofresistivity,skineffect,Halleffect:(Topic-5)
1.TemperatureDependenceofResistivity:
Resistivity(ρ)referstoamaterial'sresistancetotheflowofelectric
current.It'sinfluencedbytemperature.
Inmetals:Astemperatureincreases,theatomicvibrationsintensify,
causingmorecollisionsbetweenconductionelectronsandatoms,
whichincreasesresistivity.
????????????=??????
0[1+????????????−??????
0]
Where,
??????
0istheresistivityattemperature??????
0and??????isthetemperature
coefficientofresistivity.
Insemiconductors:Resistivitydecreaseswithtemperature,as
morechargecarriersaregeneratedathighertemperatures.

25. Temperaturedependenceofresistivity,skineffect,Halleffect:
2.SkinEffect:
Skineffectreferstothetendencyofalternatingcurrent(AC)toflow
primarilynearthesurfaceofaconductor,ratherthanuniformly
throughoutitscross-section.
Thiseffectbecomesmorepronouncedathigherfrequenciesbecause
theinductivereactancewithintheconductorincreaseswithfrequency.
Theskindepth(δ),orthedepthatwhichthecurrentdensityfallsto
1/eofitsvalueatthesurface,isgivenby:
??????=
2??????
????????????
where:??????is the resistivity,
??????is the permeability of the material,
ω is the angular frequency of the AC current.

26. Temperaturedependenceofresistivity,skineffect,Halleffect:
3.HallEffect:
Halleffectoccurswhenacurrent-carryingconductorisplacedinamagneticfieldperpendicular
tothedirectionofthecurrent,resultinginatransverseelectricfield(theHallvoltage).
Thiseffectcanbeusedtomeasuremagneticfieldstrengthorthetype(positiveornegative)of
chargecarriersinamaterial.
The Hall voltage (??????
�)is given by:
??????
�=
��
????????????�
where:
Iis the current,
Bis the magnetic field,
nis the charge carrier density,
qis the charge of the carriers,
Ais the cross-sectional area of the conductor.
Eachoftheseconceptsplaysanimportantroleinunderstandingthebehaviorofelectrical
conductorsandsemiconductorsindifferentconditions.