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Materials Synthesis & Characterization: the role of positron annihilation
Input Materials
Known Material Properties
Synthesis(Equilibrium/
non equilibrium Methods)
Modify Structure,Microstructure,
Composition
Characterization/Property
Evaluation
Physical and chemicalProperties
Suitable?
Products/Components/Applications
YES
NO
Materials Synthesis & Characterization
Application-oriented Properties
OpticalMagneticElectricalMechanical
Probes for Materials characterization - Photons, Electrons, Protons, Neutrons, Ions, Positrons
Chemistry
Structure
Microstructure
How Do We Characterise?
General Methodology of Characterisation
General Analytical Technique - Average Information from Bulk material, generally destructive
Microscopy Techniques - Solid State, Non destructive, Probe Based Techniques, Position sensitive
MaterialSource DetectorProbe Response
Classification of Materials Characterization
StructuralCharacterisation
Crystal structureMicrostructureDefect structure
ChemicalCharacterisation
Chemical natureMacro chemical analysisMicro chemical analysisMajor element (>10%)Minor element (0.1 - 10%)Trace element (1-1000ppm)Ultra trace ( < 1 ppm)
Magnetic Structure – Neutron scattering, MS, PAC
Microstructure (Impurity states, Interstitials, Vacancies, Colorcentres, dislocations, Grain boundaries) – HRTEM, UVVIS, Raman, PL, FTIR, MS, PAC, PASMicrostructure (Cracks, Voids, Precipitates, Exclusions) – NDT, TEM, SAXS, SANS
Impurities & local chemical environment – Mass Spectroscopy, ESR, NMR, Mass spectroscopy, EPMA, AES, XPS, SIMS, PIXE, Raman, PL, FTIR, PAC, PAS, XRF, EXAFS
Surface topography – Optical Microscopy, SEM, AFM, Ellipsometry
Surface composition – AES, XPS, SIMS, EPMA, RBS
Surface structure – GIXRD, FIM, LEED, Ion Channeling, STM
Bulk composition –Spectrophotometry, Mass spectroscopy
Bulk structure – XRD, TEM, HRTEM, Neutron scattering
Chemical Characterization
Structural and Microstructural
Characterization
A big canvas of characterization techniques –Microstructural, Structural and Chemical aspects
Advances in Materials characterization, Eds. G. Amarendra, Baldev Raj, M.H. Manghnani, Universities Press, Hyderabad, 2007)
AES - Auger electron spectroscopyAFM – Atomic force microscopyEPMA – Electron probe microanalysis ESR – Electron spin resonance spectroscopyEXAFS – Extended X-ray absorption fluorescence spectroscopyFIM – Field ion microscopyFTIR – Fourier transform infrared spectroscopyGIXRD – Glancing incident X-ray diffraction HRTEM – High resolution electron microscopyEXAFS – Extended X-Ray Absorption Fine Structure LEED – Low energy electron diffractionMS – Mossbauer spectroscopy NDT – Non-destructive techniques
Abbreviations for the experimental techniques
NMR – Nuclear magnetic resonance spectroscopyPAC – Perturbed angular correlation spectroscopy PAS – Positron annihilation spectroscopy PL – Photoluminescence Spectroscopy RBS – Rutherford backscattering SpectroscopySANS - Small angle neutron scatteringSAXS - Small angle X-ray scattering SEM – Secondary electron microscopy SIMS - Secondary ion mass spectroscopySTM - Scanning tunneling microscopy TEM – Transmission electron microscopyUVVIS - UV-VIS absorption spectroscopyXPS – X-ray photoelectron spectroscopyXRD – X-ray diffractionXRF – X-ray resonance fluorescence
Defects -Atomistic Imperfections
Interstitial impurity atom
Edge dislocation Vacancy
Self interstitial atomPrecipitate of impurity atoms
Vacancy type dislocation loop
Interstitial type dislocation loop
Substitutionalimpurity atom
Amorphous
Void
Macroscopic consequences – Changes in mechanical (Cracks, Fracture, Swelling), Optical, electrical & magnetic properties
Point Defect Production
Crystal Growth Quenching, i.e. rapid coolingPlastic deformationIrradiation with electrons, ions, neutronsOxidation, Nitridation, SilicidationReactive Interfaces Precipitation
Experimental techniques for defect studies
Semiconductors ResistivityDilatometryNDTXRD, SAXSElectron MicroscopySANSRBS, Ion ChannelingEPR, NMRMossbauer spectroscopyElectron microscopyPerturbed angular correlationPositron Annihilation
spectroscopy Raman scatteringInfrared & Optical absorptionEllipsometry
Metals & alloysResistivity
Dilatometry
Non-destructive techniques (NDT)
X-ray diffraction (XRD), SAXS
Electron Microscopy (SEM, TEM)
Small Angle Neutron Scattering (SANS)
Positron Annihilation spectroscopy
Perturbed angular correlation
Comparison of various experimental techniques
Defect Size vs. Depth Defect Conc. vs. Depth
Each technique has sensitivity over certain size and concentration ranges and only by judicious combination of many, one can attempt to unravel complete information.
Applicability of positrons in various branches of science
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