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