Compendium

Materials Characterization Techniques — Deep Tier 2

28 min read

Materials Characterization Techniques — Deep

Tier 2 deep companion to characterization-methods. The Tier 1 note surveys the what and which-tool-for-which-question of materials probes. This note goes deeper: every family enumerated, every common instrument named, every preparation pitfall, and every standard (ASTM E series, ISO TC 202 and TC 164, IEC 60068 environmental) called out. SI primary; instrument vendor lineup as of 2024–2026.

See also: crystallography-phase-diagrams (diffraction physics), materials-overview (front door), electronic-structure-and-computational-materials (interpretation context), ndt-methods (the bulk-defect cousins UT/RT/PT/MT — used at the part level, not the material-science lab level).

1. The big picture — what we measure and why

Materials characterization answers four families of questions:

  1. What is it made of? Composition — elemental, isotopic, phase-fraction. Tools: EDS, WDS, XPS, AES, SIMS, LA-ICP-MS, GD-OES, NMR, FTIR, Raman, XRD (phase), Mössbauer.
  2. Where is it arranged? Structure — crystal lattice, microstructure, texture, defects, porosity. Tools: XRD (powder + HRXRD), SAED, EBSD, SEM, TEM, AFM, atom probe, micro-CT, FIB tomography.
  3. What is its surface or interface? Tools: XPS, AES, SIMS, LEIS, ToF-SIMS, AFM/STM, ellipsometry, AR-XPS for depth.
  4. How does it behave? Mechanical, thermal, magnetic, electrical, optical response. Tools: instrumented indentation, DSC, TGA, DMA, VSM, SQUID, four-point probe, Hall effect, ellipsometry, UV-Vis-NIR, PL.

A complete materials study uses tools from each family. A typical thin-film characterization stack:

  • XRR for thickness, density, roughness
  • HRXRD for epitaxy / strain
  • AFM for topography
  • SEM cross-section for stack geometry
  • XPS for surface chemistry
  • ToF-SIMS for depth profile
  • Ellipsometry for optical constants n, k
  • Four-point probe and Hall for electrical
  • TEM cross-section (FIB lift-out) for defect imaging

The challenge is rarely getting data — it’s correlating data across modalities at the same region of interest. Modern correlative-microscopy workflows (FIB-SEM with site-targeted TEM lift-out; atom probe + APT-EBSD; nanoprobe SIMS + EELS) address this; cost runs to \$10–20M per fully equipped suite.

2. Diffraction techniques

2.1 X-ray diffraction — powder (PXRD)

The workhorse for phase ID, lattice parameter refinement, and texture/strain. Bragg’s law: nλ = 2d·sin(θ).

Geometry options:

  • Bragg-Brentano (θ-2θ or θ-θ) — para-focusing; sample flat, ideally <20 μm grain size, infinitely thick. Most lab diffractometers.
  • Debye-Scherrer (capillary, transmission) — sample in 0.1–1 mm capillary, rotating; better statistics for non-flat sample.
  • Grazing-incidence (GIXRD) — fixed low ω (0.5–3°), 2θ scan; surface-sensitive (penetration 100 nm–few μm), good for thin films.
  • Reflectometry (XRR) — sub-critical-angle, 0–6° in 2θ; thickness, density, roughness of layered thin films.

Sources: Cu-Kα (λ=1.5406 Å, the default), Mo-Kα (λ=0.7093 Å, deeper penetration, lower-angle for amorphous PDF), Co-Kα (λ=1.7889 Å, avoids Fe fluorescence in Fe-rich samples), Cr-Kα (high d-spacing for high-d phases). Synchrotron: tunable, ~10× brighter, ms time-resolved.

Modern instruments (2024–2025):

  • Bruker D8 ADVANCE / D8 DISCOVER / D8 VENTURE (single-crystal), D2 PHASER for QC.
  • Rigaku SmartLab Studio II (with ML phase-search engine cutting setup from hours to minutes), MiniFlex, XtaLAB Synergy-DW (single crystal).
  • Malvern Panalytical Empyrean / Aeris / X’Pert3 MRD (epitaxy).
  • Stoe STADI MP (capillary, lab PDF source).
  • Anton Paar XRDynamic 500 (multipurpose with in-situ stages).

Detectors: position-sensitive linear (LynxEye, MYTHEN), 2D area (PILATUS, EIGER, Hypix). Modern hybrid pixel detectors give 1–10 ms exposures per pattern → time-resolved is routine.

Sample preparation pitfalls:

  • Grain size — coarse grains (>40 μm) give spotty patterns; mill or rotate sample. Polished bulk: surface preparation can introduce strain → broadened peaks.
  • Preferred orientation (texture) — flat preparation of platy minerals (mica, clay) biases intensities; use spinner stage or back-loading.
  • Height displacement — sample surface above or below the diffractometer focal plane shifts 2θ. Use NIST SRM 660c (LaB₆) or 640f (Si) for calibration.
  • Fluorescence — Fe or Co samples on Cu source: fluorescence raises background. Use a monochromator on the diffracted side or a Co source.

Standards: ICDD PDF-5+ database (>1M reference patterns, 2024 release); ICSD (Inorganic Crystal Structure Database, FIZ Karlsruhe); CSD (Cambridge Structural Database, organic + organometallic).

Rietveld refinement — full-pattern fit to crystal-structure model with refinement of: lattice parameters, atomic positions, thermal parameters, peak shape, preferred orientation, microstructure (size, strain). Software: TOPAS (commercial, Bruker), GSAS-II (free, APS Argonne), FullProf, JANA2020, MAUD. Modern automated Rietveld pipelines now sit inside instrument control software.

2.2 Single-crystal XRD

Full 3D atomic structure solution. Used for: small-molecule chemistry, mineralogy, protein crystallography (separate macromolecular crystallography branch), characterization of intermetallics. Instruments: Bruker D8 VENTURE / PHOTON III, Rigaku XtaLAB Synergy-DW, Stoe StadiVari. CCD/CMOS area detectors; mostly Mo or Cu microfocus.

Workflow: mount crystal (cryoloop in cryostream 100 K typical for organic), index (unit cell from initial frames), strategy (predict completeness coverage), data collection (hours-to-days), reduction (apply absorption, Lorentz, polarization), solution (SHELXT / direct methods or charge flipping), refinement (SHELXL, OLEX2 GUI). Output: CIF file deposited in CSD or ICSD.

2.3 High-resolution XRD (HRXRD) and reciprocal-space mapping (RSM)

For epitaxial films — composition, strain, relaxation, thickness fringes. Triple-axis monochromator (4-bounce Ge(220) or (440)) gives Δλ/λ ~10⁻⁴. ω-2θ scan around a substrate Bragg peak: film peak position gives composition (Vegard’s law for ternary like SiGe, InGaAs); fringe spacing gives film thickness (Δω = λ/(2t·cos(ω))).

Reciprocal-space map — 2D q_x-q_y map around an asymmetric reflection (e.g., (115) for cubic, (105) for hexagonal); separates strain from composition by independently measuring in-plane and out-of-plane lattice parameter.

Standard in compound-semiconductor fabs (Sumika, II-VI, Coherent, MicroLED foundries).

2.4 Small-angle scattering (SAXS/WAXS, USAXS)

Nanoscale structure at 1–100 nm. Standard tools: Anton Paar SAXSpoint 5.0, Xenocs Xeuss 3.0 with Pilatus3 R 300K detector, Bruker NANOSTAR. GISAXS (grazing-incidence) for thin films; standard at every block-copolymer and organic-PV lab.

SAXS analysis: Guinier regime (low q) → radius of gyration R_g. Porod regime (high q) → surface area / fractal dimension. Form factors (sphere, cylinder, lamella) → size distribution. Software: SasView (open-source), Anton Paar SAXSanalysis, Igor NIST package, Bruker SAXSquant.

2.5 Pair distribution function (PDF, total scattering)

For amorphous and nanocrystalline materials. Take a wide-Q scattering pattern (Q up to 25–30 Å⁻¹), Fourier-transform to real space → G(r), the probability of finding atom pairs at distance r. Lab Mo or Ag sources or synchrotron beamlines (APS 11-ID, NSLS-II XPD, ESRF ID22). Standard for: metallic glasses, amorphous oxides, nanoparticles, cathode materials. Software: PDFgui, PDFfit2, xPDFsuite, DiffPy.

2.6 Neutron diffraction

Complementary to XRD because:

  • Light-element sensitivity — H, Li, O, C have very low X-ray scattering but moderate neutron cross-sections (positive for some, negative for H).
  • Isotope contrast — H vs D differs strongly; deuterated samples for soft-matter studies.
  • Magnetic structure — neutron spin couples to electron magnetic moment; only way to map magnetic moments in real space (vs bulk magnetometry).
  • Deep penetration — cm-deep into Fe, Al, Ti; characterizes bulk parts non-destructively (engineering diffractometers HIPPO, ENGIN-X, VULCAN).
  • No radiation damage for most samples.

Sources: ORNL HFIR + SNS (USA), ILL (France), ISIS (UK), J-PARC (Japan), FRM-II (Germany), CSNS (China), ANSTO OPAL (Australia). Beam time competitive (proposal-based, 1–7 days per experiment).

2.7 Electron diffraction in TEM (SAED, CBED, 4D-STEM)

In a TEM, the parallel-beam diffraction pattern from a selected area (SAED) or convergent-beam from a focused probe (CBED) reveals nanoscale crystallography. CBED Higher Order Laue Zones encode 3D symmetry; HOLZ-line analysis gives lattice parameters to ~10⁻⁴.

4D-STEM — modern fast-detector technique (Gatan K3, Direct Electron Apollo, Dectris ELA, Thermo Fisher EDAX-Velox): scan focused probe, record full 2D diffraction at each pixel → 4-dimensional dataset. Maps strain, orientation (ACOM-TEM, NanoMEGAS ASTAR), and even ferroelectric polarization at nm resolution.

2.8 Electron backscatter diffraction (EBSD) in SEM

Orientation mapping of polycrystalline material. Backscattered electrons from a tilted (~70°) sample produce Kikuchi patterns; pattern indexing gives 3 Euler angles per pixel. Maps to 50 nm typical, down to 10 nm on field-emission SEM with newer CMOS direct-detection cameras.

Modern detectors: Oxford Symmetry S3, Symmetry S2; EDAX Velocity Super / Velocity Pro; Bruker eFlash HD. Detection at ~5000 patterns/second (Symmetry S3, 2023).

Pattern indexing methods:

  • Hough-transform (classic) — fast, robust for well-indexed materials.
  • Dictionary indexing — match against simulated patterns; works for HCP and complex multi-phase.
  • Spherical indexing (Marquardt, EMsoft 2017+) — fast, deep.

Pseudo-symmetry pitfalls (BCC vs FCC at certain orientations; trigonal in cubic setting) are well-documented; modern software flags them.

Companion techniques in SEM:

  • Transmission Kikuchi diffraction (TKD) — same Kikuchi patterns from thinned (FIB-prepared) electron-transparent sample; spatial resolution 10–30 nm.
  • HR-EBSD (high-resolution EBSD) — cross-correlation of reference and target pattern → elastic strain/rotation tensor at 10⁻⁴ resolution.

3. Imaging techniques

3.1 Optical microscopy

Light microscopy is the first-look for any metallographic sample. Polished + etched specimen reveals grain structure (Nital etch for steel; Keller for aluminum; Kroll for Ti; Murakami for stainless). Modern instruments: Zeiss Axio Imager + Smartzoom 5; Leica DM6 M / DM4 M; Olympus DSX1000 (digital, EDOF); Nikon LV150NL / Eclipse MA200. Standards: ASTM E3 specimen preparation, ASTM E407 etchants.

Specialty modes:

  • Bright-field, dark-field — phase identification and contrast.
  • Polarized light — birefringence; mineralogical and polymer identification.
  • Differential interference contrast (DIC, Nomarski) — height contrast on featureless surfaces.
  • Fluorescence — labeled organics, biofilms.
  • Confocal laser scanning (Keyence VK-X / VHX, Olympus LEXT OLS5100, Zeiss Smartproof 5) — optical sectioning, surface metrology Ra/Sz.
  • White-light interferometry (WLI) — Zygo NewView, Bruker Contour, Filmetrics Profilm3D; sub-nm vertical resolution for surface topography.
  • Hyperspectral / chemical imaging — μ-FTIR, μ-Raman, fluorescence lifetime.

3.2 SEM family

Scanning electron microscopes are the high-throughput imaging workhorse. See characterization-methods §2 for detailed signal-and-instrument coverage. This section extends with three less-covered topics.

Variable-pressure / environmental SEM — chamber at 10–4000 Pa H₂O or other gas; allows imaging of wet, biological, or charging samples without coating. Modern: Hitachi SU3900, Thermo Fisher Quattro S/ESEM (with up to 4000 Pa H₂O and Peltier stage), Zeiss EVO 25.

FIB-SEM dual beam — Ga (legacy), Xe-plasma (Thermo Fisher Helios Hydra, Zeiss Crossbeam 550 plasma, TESCAN SOLARIS X), or fs-laser front-end. Used for:

  • Cross-section preparation (typical 10×10 μm window).
  • TEM lift-out (FIB-cut a ~10×5×0.1 μm lamella, weld to TEM grid, thin to electron transparency).
  • Serial sectioning / FIB tomography (slice + image stack, reconstruct 3D microstructure at ~10 nm voxel).
  • Atom probe specimen sharpening (FIB sharpening to a <100 nm-tip).

In-situ stages:

  • Heating (Aduro / DENSsolutions Wildfire, Protochips Fusion).
  • Cooling (cryo).
  • Mechanical (Hysitron PI 88, Bruker Hysitron PicoIndenter).
  • Gas / liquid (Atmosphere from Protochips for STEM environmental).

3.3 TEM family

Transmission electron microscopes resolve to sub-Å in HRTEM / aberration-corrected STEM. Sample must be electron-transparent: <100 nm thick, often <50 nm.

Instruments (2024–2025):

  • Thermo Fisher Krios G4 Cryo-TEM — life-sciences (single-particle, tomography); also nanomaterials cryo.
  • Thermo Fisher Spectra 300 / Themis Z — aberration-corrected STEM, ~50 pm probe at 300 kV.
  • Thermo Fisher Talos F200X / G2 — workhorse 200 kV S/TEM.
  • JEOL JEM-ARM200F / ARM300F NEOARM — aberration-corrected, monochromated for high-energy-resolution EELS (~10 meV); the standard for advanced functional materials.
  • JEOL JEM-F200 — modern 200 kV cold-FEG.
  • Hitachi HF5000 / HD-2700 — 200 kV STEM dedicated.
  • Nion UltraSTEM 200CC — monochromated, sub-10 meV EELS (vibrational spectroscopy in EELS).

Signals: bright-field, dark-field (DF), high-angle annular dark-field (HAADF — Z² contrast for STEM), bright-field STEM, ABF (annular bright field for light atoms), EELS, EDS, 4D-STEM, electron tomography. Modern HAADF achieves single-atom imaging with column visibility down to Z~5.

Cryo-EM — frozen-hydrated specimen at 80–100 K in liquid-ethane-vitrified state. Originally biology; nanomaterials cryo addresses beam-sensitive samples (organic photovoltaics, MOF/COF, lithium battery materials, soft-matter assemblies).

Aberration correctors — Cs (spherical) correctors from CEOS GmbH (DCOR, ASCOR, CETCOR) brought TEM resolution from 0.2 nm to <0.05 nm and STEM probes to <50 pm. Standard above 200 kV. Cc (chromatic) correctors emerging in TEAM-style and Krios-style instruments.

3.4 Scanning probe family

AFM (atomic force microscopy) — sharp tip on cantilever, surface raster, deflection measured by laser bouncing off cantilever. Modes:

  • Contact — constant force, drag tip; gives lateral force (friction) too.
  • Tapping / intermittent contact — oscillate cantilever near resonance, image with amplitude or phase feedback; minimal sample damage; the default for soft samples.
  • Non-contact / FM-mode — UHV AFM; sub-atomic-resolution imaging of metal and semiconductor surfaces.
  • Conductive AFM (C-AFM) — current map alongside topography.
  • PFM (piezoresponse force microscopy) — AC bias applied; image local ferroelectric domains.
  • KPFM (Kelvin probe FM) — DC bias servoed to null electrostatic force; gives surface potential / work function with ~10 mV resolution.
  • MFM (magnetic force) — magnetized tip; image magnetic domain structure.
  • SThM (scanning thermal) — resistive tip; map thermal conductivity, 50 nm spatial.
  • PeakForce QNM (Bruker) — quantitative nanomechanics (modulus, adhesion) on every pixel.

Modern instruments: Bruker Dimension Icon / Dimension XR / FastScan; Park Systems NX-Hivac / NX20 / FX40; Asylum (Oxford Instruments) Cypher / Jupiter; Anasys nanoIR3 (AFM + IR spectroscopy on the tip → 10 nm chemical mapping); Witec alpha300 RAS combines AFM + Raman.

STM (scanning tunneling microscopy) — tip-sample tunnel current at ~1 nA, sub-Å z-resolution. Atomic resolution on conductors in UHV; molecular orbital imaging; quasiparticle interference (QPI) mapping for topological materials. Vendors: Omicron / Scienta Omicron, RHK Technology, Createc, Unisoku, SPECS, Bruker (Multimode VIII), Park (NX).

Atom probe tomography (APT) — sharpest tip + highest-field probe in all of materials science. Sample: needle ~50 nm radius. High voltage (or pulsed laser) field-evaporates atoms one at a time; position detector (delay-line crossed-wire) and time-of-flight mass spectrometer reconstruct 3D atom-by-atom composition with ~0.3 nm spatial resolution. Vendors: CAMECA LEAP 5000 XS / XR / XT, 6000 series (2023+).

Standards for APT: ISO 18115-2 surface chemical analysis; community-driven IVAS / APsuite software.

3.5 X-ray tomography (micro-CT, nano-CT)

3D imaging by rotation + reconstruction. Spatial resolution: micro-CT 0.5–10 μm; nano-CT (with X-ray-optics) 50–500 nm; synchrotron 20–100 nm. Used for: foam structure, additive-manufacturing porosity, biomaterial scaffolds, cement microstructure.

Instruments: Zeiss Xradia Versa 630 (lab nano-CT), Bruker SkyScan 1276 / 2214 / 2275 (micro-CT), GE Phoenix Nanotom / vtomex (large-volume), Rigaku NX series. Synchrotron beamlines (APS 2-BM, ESRF ID19, Diamond I12) for time-resolved.

4. Spectroscopy

4.1 Photoelectron spectroscopy — XPS, UPS, HAXPES

XPS (X-ray Photoelectron Spectroscopy / ESCA) — monochromated Al-Kα (1486.6 eV) or Mg-Kα (1253.6 eV); measure kinetic energy of emitted photoelectrons → binding energy → chemical state (oxidation state, bonding environment). Surface-sensitive: photoelectron inelastic mean-free-path 1–10 nm → typical sampling depth 3 × IMFP × cos(θ).

Modern instruments: Thermo Fisher K-Alpha / Nexsa G2 / ESCALAB Xi+; Kratos Axis Supra+ / Ultra DLD / Nova; SPECS Phoibos / EnviroESCA (near-ambient pressure); ULVAC-PHI VersaProbe 4 (small-area Auger-style imaging).

Modes:

  • Survey scan — element identification, ~1 atomic %.
  • High-resolution scan — chemical state from peak shift (C 1s shifts ~3 eV between C-C and C=O; Mn 2p shifts between Mn²⁺ / Mn³⁺ / Mn⁴⁺).
  • Depth profile — Ar+ ion etch + measure; cluster-Ar (Ar_n+ n=500–2000) for soft / organic / polymer samples.
  • Angle-resolved (AR-XPS) — vary detection angle → vary sampling depth → non-destructive depth profile <10 nm.
  • Near-ambient-pressure XPS (NAP-XPS) — operando catalysis at mbar pressures.

Standards: ISO 18115, 18118, 18516, NIST XPS database, AIST XPS database.

UPS (Ultraviolet Photoelectron Spectroscopy) — He-I (21.2 eV) or He-II (40.8 eV) source; probes valence band, work function. Standard for: organic semiconductor energy alignment, work-function measurement, density-of-states near Fermi level.

HAXPES (Hard X-ray Photoelectron Spectroscopy) — 5–10 keV photon, deeper sampling (10–50 nm); for buried interface chemistry. Synchrotron + a growing number of lab instruments (Scienta Omicron HAXPES Lab with Ga-Kα 9.25 keV).

4.2 Auger electron spectroscopy (AES)

Smaller probe than XPS (down to 10 nm spot), better lateral resolution; sensitive to first 1–5 nm. Used for: small-feature contamination, semiconductor / microelectronics, surface segregation studies. Modern: Thermo Fisher MICROLAB 350, ULVAC-PHI 710 / 660 Scanning Auger.

4.3 Secondary ion mass spectrometry (SIMS, ToF-SIMS, NanoSIMS)

Primary ion (Cs⁺, O₂⁺, Bi₃⁺, Ar gas cluster) sputters surface; secondary ions analyzed by mass spectrometer.

  • Dynamic SIMS (quadrupole or magnetic sector) — depth-profile concentration vs depth; ppb sensitivity; standard for semiconductor dopant profiling.
  • Static SIMS / ToF-SIMS — low primary dose, time-of-flight MS; full mass spectrum at every pixel; molecular fragment ID for organics / coatings.
  • NanoSIMS (CAMECA NanoSIMS 50L) — Cs⁺ or O⁻ focused to ~50 nm; isotope-ratio at sub-μm; geosciences, biology, batteries.

Modern instruments: CAMECA IMS 7f / SC Ultra (dynamic), CAMECA IMS 1280-HR (geosciences), IONTOF M6 / 5 (ToF-SIMS), ULVAC-PHI nanoTOF 3+ (ToF-SIMS with 200 nm primary probe).

4.4 LA-ICP-MS, GD-OES

Laser-ablation ICP-MS — UV laser (213 or 193 nm) ablates 10–100 μm pit; ablated aerosol carried to ICP-MS for elemental + isotopic. Used for: solid-sample geochemistry, rare-earth element traces.

Glow-discharge OES/MS — Ar discharge sputters sample; emission or MS analyses removed material. Bulk + depth-profile to ~100 μm at ~1 μm/s. Industrial workhorse for steel + Al + Cu alloy QC. Spectro GDS / GDA, Leco GDS900, ULVAC-PHI GD-OES.

4.5 EDS / WDS in electron microscopes

Energy-dispersive X-ray spectroscopy (EDS / EDX) — silicon-drift detector (SDD), 50–150 mm² active area, 120–135 eV resolution at Mn-Kα. Standard on every modern SEM and TEM. Maps to 1 μm in SEM, 1 nm in STEM. Modern: Oxford Ultim Max (170 mm²), Bruker XFlash 7 (160 mm² dual), EDAX Octane Elite (150 mm²).

Wavelength-dispersive X-ray spectroscopy (WDS) — diffracting crystal selects single wavelength; 5–10× better energy resolution → resolves overlapping peaks (S-Mo, Pb-S, P-Zr) and quantitative trace work down to ~10 ppm. Electron microprobe instruments: JEOL JXA-iHP200F, Cameca SXFiveFE, Shimadzu EPMA-1720.

4.6 EELS, XAS, XANES, EXAFS

Electron energy-loss spectroscopy (EELS) in TEM — measures energy-loss spectrum of transmitted electrons; gives composition (elemental), oxidation state (energy-loss near-edge structure, ELNES), bonding (extended energy-loss fine structure), and even phonons (vibrational EELS with monochromator < 10 meV). Modern detector: Gatan GIF Continuum / K3 IS, EDAX OneView. Nion’s monochromated UltraSTEM enables vibrational EELS at <10 meV.

X-ray absorption spectroscopy (XAS) — at a synchrotron, tune photon through an absorption edge:

  • XANES (X-ray absorption near-edge structure) — first ~50 eV above edge; oxidation state, coordination geometry. Fingerprint catalyst speciation.
  • EXAFS (extended X-ray absorption fine structure) — 50–1000 eV above edge; bond distances, coordination numbers, local disorder around the absorbing atom. Element-specific; works on amorphous, dilute, in-situ.

XMCD (X-ray magnetic circular dichroism) — element-specific magnetic moments via spin-resolved XAS. Standard at ALBA BL29, SOLEIL DEIMOS, NSLS-II 23-ID.

4.7 EDS chemical imaging

Routine: 2 μm SEM-EDS spectral cube, 10–100 element maps. Modern hardware enables 10⁶-pixel maps in minutes. Quantification: Cliff-Lorimer (TEM) or ZAF / PhiRhoZ (SEM); software (Oxford AZtec, Bruker Esprit, EDAX APEX, Thermo Fisher Pathfinder) automates phase identification + cluster analysis.

4.8 FTIR, Raman, photoluminescence

FTIR (Fourier-transform infrared) — vibrational spectrum 400–4000 cm⁻¹; functional-group identification, polymer chemistry, organic contamination.

  • Transmission (KBr pellet, NaCl plate).
  • ATR (attenuated total reflectance, diamond or Ge crystal) — needs no sample prep, the default for solids since 2005.
  • Reflection (specular, diffuse — DRIFTS).
  • Mapping / imaging FTIR with a focal-plane array detector — chemical map at ~5 μm.
  • Synchrotron-FTIR microscopy at sub-μm.

Modern instruments: Bruker INVENIO R / VERTEX 80v (vacuum), Thermo Fisher Nicolet iS50 / iS20, Agilent Cary 660. AFM-IR (Anasys / Bruker nanoIR3) brings spatial resolution to ~10 nm by detecting tip thermal expansion under tunable IR illumination.

Raman spectroscopy — inelastic scattering of monochromatic laser; complementary selection rules to IR (symmetric vibrations stronger). Modern instruments: WITec alpha300 (confocal Raman + AFM + SNOM); Renishaw inVia / Qontor; HORIBA LabRAM Soleil / XploRA; Thermo Fisher DXR3 / iXR; Bruker SENTERRA / MultiRAM.

Specialty modes:

  • Confocal Raman imaging — sub-μm 3D chemical map.
  • TERS (tip-enhanced Raman) — plasmonic tip → 10 nm chemical mapping.
  • SERS (surface-enhanced Raman) — Ag / Au nanoparticle substrate → 10⁶-10⁸× enhancement for trace detection.
  • Stimulated Raman scattering (SRS), CARS — coherent Raman for fast bio-imaging.
  • Raman in process — Kaiser RXN5 / EndoProbe — in-line manufacturing.

Photoluminescence (PL) — laser-pumped emission; band-gap, defect levels, quantum-dot brightness, ALD-film purity. Time-resolved PL (TRPL) gives carrier lifetime; PLE (excitation-mapped) maps absorption-emission relationships.

4.9 NMR — solid-state

Magic-angle spinning (MAS NMR) — rotor at 54.74° (magic angle) at 30–100 kHz; averages anisotropic interactions and recovers narrow lines for crystalline solids. Standard nuclei: ¹H, ¹³C (cross-polarized CP-MAS), ²⁹Si, ²⁷Al, ³¹P, ¹⁵N, ¹⁹F, ⁷Li (battery materials), ²³Na, ⁵¹V. Spectrometers: Bruker AVANCE NEO 600 / 800 / 1000 / 1.2 GHz (Lyon, 2020); JEOL ECZ; Varian (legacy).

Used for: zeolite framework, glass network, polymer chain dynamics, MOF framework, perovskite halide ordering, battery cathode Li environments, metal-organic complex chemistry.

4.10 EPR / ESR

Electron Paramagnetic Resonance — for unpaired-electron systems (transition-metal complexes, radicals, defects). Microwave absorption in magnetic field. Standard X-band (~9 GHz) and Q-band (~35 GHz). Bruker EMXmicro / E580 (pulsed), Magnettech MS5000.

4.11 Mössbauer spectroscopy

Recoil-free γ-ray absorption — for ⁵⁷Fe (most common), ¹¹⁹Sn, ¹²¹Sb, ⁶¹Ni, ¹⁶¹Dy and a few others. Reveals oxidation state, magnetic ordering, hyperfine field, quadrupole splitting. Standard tool for iron-bearing minerals, steel phase quantification (austenite/ferrite/martensite, magnetic vs paramagnetic), Fe nanoparticle characterization. Instruments: SeeCo / WissEl spectrometers, Topometrix CMTE.

4.12 Positron annihilation lifetime spectroscopy (PALS)

Positron from ²²Na source; positron-electron annihilation lifetime depends on local electron density and thus on free-volume / vacancy concentration. Sensitive to ppb vacancy concentrations in metals, free-volume distribution in polymers (size and volume fraction of nanopores 0.3–1 nm). Lab + reactor / accelerator slow-positron beams (HZDR ELBE, NEPOMUC at FRM-II).

5. Thermal analysis

5.1 DSC (differential scanning calorimetry)

Measures heat flow into / out of sample as function of T. Reveals: glass transition (T_g), melting (T_m), crystallization (T_c), solid-solid transformations, polymerization / curing exotherms, decomposition. Modern instruments:

  • TA Instruments Q2000 / Discovery DSC 250 / 2500.
  • Mettler Toledo DSC 3 / Flash DSC 2+ (the Flash version operates at 10⁵ °C/s — quenches and characterizes metallic glasses, polymer crystallization at near-melt rates).
  • Netzsch DSC 214 Polyma / 404 F1 Pegasus (HT to 2400 °C).

Modulated DSC (TA), Power-compensated DSC (PerkinElmer DSC 8000) — separates reversing and non-reversing heat flow → cleanly resolves T_g from overlapping enthalpy events.

Standards: ASTM E967, E968, E1356 (T_g); ASTM D3418 (polymers); ISO 11357.

5.2 TGA, simultaneous TGA-DSC

Thermogravimetric analysis — sample mass as function of T. Reveals: dehydration, decomposition, oxidation, reduction (in H₂ atmosphere), char yield. Coupled to FTIR or MS (TGA-FTIR, TGA-MS) for evolved-gas analysis. Modern: TA Discovery TGA 5500 / 550, Netzsch TG 209 F3, Mettler TGA/DSC 3+ STAR.

5.3 DMA (dynamic mechanical analysis)

Oscillating force on polymer or composite sample, measure storage (E’) and loss (E”) modulus vs T or frequency. Standard for polymer T_g, time-temperature superposition, viscoelastic master curves. Modern: TA Instruments DMA 850 / RSA-G2, Netzsch DMA 242 E, Mettler DMA 1.

5.4 Dilatometry, DTA, microcalorimetry, MCC

Dilatometry — measures sample length vs T → thermal expansion coefficient (CTE), phase transition strain (e.g., martensitic shape recovery). Push-rod, optical (Linseis L75 PT), high-vacuum (Linseis DIL L78). For steel, dilatometry resolves the austenite → ferrite/pearlite/bainite/martensite transformations on a CCT diagram.

DTA (differential thermal analysis) — older, simpler cousin of DSC; ΔT between sample and reference. Still common in geosciences and refractories.

Microcalorimetry / Calvet / Tian-Calvet — high-sensitivity heat flux; characterizes weak transitions, adsorption isotherms, biological samples. Setaram BT 2.15, TA Nano-DSC.

Microscale combustion calorimetry (MCC, ASTM D7309) — characterizes polymer flammability; outputs heat release capacity, total heat release.

6. Mechanical and mechano-physical characterization

6.1 Macro mechanical testing

Standard tensile (ASTM E8 / ISO 6892), compression (ASTM E9), bend (ASTM E290), shear, fatigue (ASTM E466 / ISO 1099, axial; ASTM E647 / ISO 12108, crack growth), creep (ASTM E139), impact (Charpy ASTM E23, Izod ASTM D256), fracture toughness (K_IC by ASTM E399, J_IC by ASTM E1820). Instruments: Instron 5900 / 6800 series, MTS Insight / Criterion / Landmark / Acumen series, Zwick Roell zwickiLine / zwickline / AllroundLine / Vibrophore.

Specialty:

  • Servo-hydraulic for high-rate (10–100 m/s) and fatigue.
  • Drop tower for impact (ASTM E2298, ISO 6603).
  • Split Hopkinson pressure bar (SHPB) for high strain rates 10³–10⁵ s⁻¹.
  • Climatic chambers for –150 °C to +600 °C testing.

6.2 Instrumented indentation / nanoindentation

Standardized in ISO 14577 (Oliver-Pharr method). Load-displacement curve gives reduced modulus E_r and hardness H from contact area at unloading. Instruments: Bruker Hysitron TI 980 / TI 950, KLA iMicro / iNano, Anton Paar NHT/UNHT, Fischer Picodentor HM500.

Modern moves:

  • High-throughput indentation mapping — automated grid of 1000+ indents → modulus + hardness map, used for combinatorial alloy discovery.
  • High-temperature nano-indentation to 800 °C (Bruker Hysitron, Micro Materials NanoTest Vantage).
  • In-situ SEM/TEM indentation (Hysitron PI 88 PicoIndenter, Bruker PI 95 / PI 89) — observe deformation mechanism live; quantitative compression of micropillars / micro-cantilevers.

6.3 Tribometry

Wear, friction, lubrication. Pin-on-disc (ASTM G99), ball-on-disc, ball-on-three-discs (4-ball, ASTM D4172 for lubricants), reciprocating (ASTM G133). Instruments: Anton Paar TRB³, Rtec Instruments MFT-5000, Bruker UMT, CETR.

Modern moves: in-situ Raman or AES at the contact for tribochemical-film characterization; high-frequency reciprocating rig (HFRR) for fuel lubricity; AFM-based nano-tribometry.

Coverage: tribology.

6.4 Fatigue and creep rigs

Servo-electric or servo-hydraulic; load-controlled or strain-controlled; isothermal or thermo-mechanical (TMF). High-T creep at 500–1100 °C with constant-load lever-arm (NPL Mayes / ATS / Zwick LCF rigs). For very long-term creep (10⁴ h+), national-laboratory campaigns (NIMS Japan, ORNL US).

6.5 Nanoscale and in-situ mechanical

MEMS-based push-to-pull devices + electron microscope for in-situ tensile of nanowires, thin films at sub-μm sizes (Hysitron PI 95 with PTP devices).

Brillouin scattering — inelastic light scattering from phonons → elastic constants without contact. Standard for thin films and biological tissues.

7. Surface area, porosity, particle size

7.1 BET nitrogen sorption

Brunauer-Emmett-Teller surface area at 77 K liquid-nitrogen. Standard for: catalyst supports, MOF/COF, activated carbon, battery electrode powders. Modern: Micromeritics 3Flex / ASAP 2460 / TriStar II Plus / 3030 / 3022; Anton Paar Autosorb-iQ-XR / Quadrasorb / NOVA 800; BELSORP MAX-II. Output: SSA in m²/g; pore-size distribution by BJH (Barrett-Joyner-Halenda mesopore), HK / SF (Horvath-Kawazoe / Saito-Foley micropore), NL-DFT, QSDFT (gold-standard for mixed pore systems). Standards: ISO 9277, ISO 15901.

7.2 Mercury intrusion porosimetry (MIP)

Wet Hg into pores; pressure-volume curve gives pore-size distribution 3 nm–800 μm. Standard: ASTM D4404, ISO 15901-1. Instruments: Micromeritics AutoPore V, Anton Paar PoreMaster, Quantachrome PoreMaster.

Caveat: Hg toxicity + environmental regulation has pushed labs to alternative gas-sorption methods; in 2025 several countries restrict MIP to specific licensed facilities.

7.3 Particle size

TechniqueRangeUse
Dynamic light scattering (DLS)1 nm–10 μmAggregates in suspension; rapid; Malvern Zetasizer Ultra / Pro, HORIBA SZ-100
Static light scattering (Mie)0.1–3000 μmBulk powder; Malvern Mastersizer 3000, HORIBA LA-960
Laser diffraction0.01–3000 μmCement, ceramic, pharma; standard ISO 13320
Sedimentation0.1–100 μmDensity-based; ISO 13317
Sieve analysis20 μm–100 mmCoarse particles; ASTM E11, ISO 3310
Electrozone (Coulter)0.4–1600 μmBeckman Coulter
Image analysis1 μm+Automated SEM (Sympatec, Microtrac MRB CAMSIZER X2)
SAXS1–100 nmSee §2.4

7.4 Zeta potential

Electrokinetic / electrophoretic mobility → zeta potential; predicts colloidal stability. Modern: Malvern Zetasizer Ultra, Anton Paar Litesizer 500, HORIBA SZ-100. ISO 13099-1.

8. Magnetic and electrical characterization

8.1 Bulk magnetometry

VSM (vibrating-sample magnetometer) — sample oscillates in fixed field; induced voltage in pickup coils gives moment. Range: 10⁻⁶ to 10² emu. Field: ±2 to ±14 T (superconducting magnet). Instruments: Quantum Design PPMS DynaCool with VSM option, Lake Shore 8400 / 7400, MicroSense EZ7 / EV9.

SQUID (superconducting quantum interference device) — most sensitive: 10⁻⁸ emu. Quantum Design MPMS 3, Cryogenic Ltd S700/S900. Common for: dilute magnetic semiconductors, rare-earth nano-magnets, magnetic protein assemblies.

AC susceptometry — small AC field on top of DC bias → frequency-dependent χ’ and χ” → relaxation, Curie-Weiss, glass transitions in spin glasses.

Magneto-optical (MOKE) — Kerr rotation of polarized light reflection; surface-sensitive, fast imaging of magnetic domains; Evico Magnetics, Durham MagOptics.

8.2 Domain imaging

MFM (§3.4), Kerr microscopy (Evico, Zeiss-based), Lorentz TEM (in-line magnetic-field imaging in TEM), electron holography for quantitative magnetic + electrostatic potential. Spin-polarized STM for atomic-scale magnetism.

8.3 Electrical: bulk and contact

Four-point probe — resistivity bulk + thin film without contact-resistance error. Manual (Jandel, Ossila) or automated (KLA Tencor, KLA Surfscan).

Hall effect / van der Pauw — carrier density, mobility, type. Hall, ECOPIA HMS-7000 / 5500, Lake Shore 8400 (with sample rotator), Nanometrics HL5500, Linseis HCS-1.

Eddy-current and impedance — coatings, plate thickness, conductivity. Foerster SIGMATEST, Fischer SIGMASCOPE.

Impedance spectroscopy / dielectric — ionic conductivity, dielectric ε’, loss tan δ. Solartron 1260+1287, Novocontrol Concept 80, Bio-Logic VSP-300. Standard in fuel cell + battery + ferroelectric research.

ECIS (electric cell-substrate impedance sensing) — Applied BioPhysics — for cell-attachment and barrier-function studies on biomaterials.

8.4 Photoconductivity and quantum efficiency

For PV cells and detectors: Newport / Oriel solar simulator (AM 1.5G), Bentham PVE300 / Enlitech QE-R EQE measurement, Imec SPECTRADIODE for IQE. Standards: ASTM G173, IEC 60904.

9. Optical and ellipsometric characterization

9.1 Spectroscopic ellipsometry

Polarization-state change after reflection → complex refractive index n + ik, layer thicknesses. Sub-nm thickness, wide spectral range (UV-Vis-NIR-MIR). Modern instruments: J.A. Woollam M-2000 / RC2-XI / IR-VASE; HORIBA Auto-SE / UVISEL Plus; Sentech / Accurion. Used widely for: ALD-film process control, semiconductor stack, anti-reflection coatings, perovskite-PV layers.

9.2 UV-Vis-NIR spectroscopy

Transmission / reflectance / diffuse reflectance over 200–2500 nm. Determines band-gap (Tauc plot), absorption coefficient, color. Modern: PerkinElmer Lambda 1050+ / Lambda 750 / Lambda 365, Agilent Cary 5000 / 5000i, Shimadzu UV-3600.

9.3 Fluorescence and PL

Already covered in §4.8. Time-resolved PL with picosecond / nanosecond pulsed sources (Horiba DeltaPro, PicoQuant FluoTime 300, Edinburgh Instruments LifeSpec II).

9.4 FTIR microscopy and IR ellipsometry

§4.8. IR-ellipsometry: J.A. Woollam IR-VASE Mark II to 30 μm wavelength; characterizes thin films + bulk crystals in MIR.

10. Cross-cutting and operando techniques

The fastest-growing area in characterization is operando — measuring during the function. Examples:

  • In-situ XRD on battery electrodes during charge/discharge: track Li intercalation, phase change.
  • NAP-XPS during catalysis in CO oxidation, hydrogen evolution, ammonia synthesis.
  • In-situ TEM with environmental cell (Protochips Atmosphere, DENSsolutions Climate) for gas-solid reactions at 1 atm.
  • In-situ heating TEM to 1500 °C (Aduro / Wildfire MEMS chip).
  • Cryo-TEM for beam-sensitive Li-batteries, MOFs, organics.
  • In-situ mechanical TEM (Hysitron PI 95 + PTP devices) — quantitative tension on nanowires while imaging dislocations.

Synchrotron and neutron-source schedules increasingly emphasize operando infrastructure (e.g., APS-U battery line, NSLS-II catalysis line, SNS engineering diffraction beamline VULCAN).

11p. Edge cases / gotchas

  • Sample preparation is half the answer. Polishing artefacts, ion-beam damage (Ga FIB amorphizes 5–20 nm; Xe-plasma is gentler at ~2 nm), electron-beam damage (organics, MOFs, perovskite degrade in seconds), oxidation (transfer in dry-glovebox to UHV cluster tool), charging (insulators in SEM/XPS).
  • Beam damage — every electron / ion / X-ray flux can change the sample. ALARA dose principles: image at lowest dose that answers the question, use a fresh region for the “real” measurement after exploratory work.
  • Statistical sampling — a single SEM image of 10 μm × 10 μm is ~0.0001 % of a 1 cm² sample. Need automation (Thermo Fisher Maps, Zeiss ZEN Connect, EDAX Velocity), Stereology methods (point counting, ASTM E1245), or representative-volume-element (RVE) analysis.
  • Calibration — every instrument drifts. NIST SRMs (660c LaB₆ for XRD, 661 photoelectron line position for XPS, 484f magnification standard for SEM), in-house standards, regular instrument checks.
  • Quantification limits — XPS sensitivity factors are theoretical; matrix effects can bias by 30 %. EDS for light elements (B, C, N, O) requires careful background subtraction. Pre-existing surface oxides confound any “bulk” composition measurement on metal samples.
  • Conflicts between techniques — XPS sees 3 nm, EDS in SEM sees 1 μm. A surface contamination layer reads strong on XPS but weak on EDS. Always cite probe depth.
  • Vacuum compatibility — UHV instruments (XPS, AES, atom probe) cannot tolerate volatile samples; water, organics, polymers may need pre-bake or low-T transfer.
  • Standards expire — ICDD PDF subscriptions, NIST SRM lots, atomic-form-factor tables (recently updated 2020 IT-C). Verify current edition before publication.
  • Phase ID without reference data — uncommon polytypes, off-stoichiometry phases, metastable phases may not be in PDF. Use Pawley + atomic-pair-distribution refinement; or solve from SAED + HRTEM + EDS.
  • Quantitative TEM / STEM — beam current, sample thickness, channeling all bias EDS/EELS. Use absorption corrections (Cliff-Lorimer with k-factor + ζ-factor), reference standards, and cross-check with XPS or LA-ICP-MS.
  • Anisotropy — single-point measurement on textured samples is misleading. Map orientation (EBSD) first, then sample in known directions.
  • Modeling required — many techniques (XRR, ellipsometry, XAS-EXAFS, SAXS form-factor) give a parameterized model fit, not a direct image. Model assumptions (number of layers, scatterer shape) bias the answer.

12p. Tools & software

XRD analysis — TOPAS (Bruker, commercial; the gold standard), GSAS-II (APS, open-source), FullProf (free), JANA2020 (Czech AS), Match! (CrystalImpact), HighScore Plus (Malvern Panalytical), PDXL2 (Rigaku), DIFFRAC.SUITE (Bruker).

Single-crystal solution — SHELXT / SHELXL (Sheldrick), OLEX2 (GUI), CRYSTALS, WinGX, Mercury (CCDC for visualization).

SAXS analysis — SasView (open), Anton Paar SAXSanalysis, ATSAS (EMBL for biology), Igor NIST package.

PDF analysis — PDFgui / PDFfit2, xPDFsuite, DiffPy CMI.

TEM/STEM analysis — Gatan DigitalMicrograph + GMS, Thermo Fisher Velox, JEOL DigitalMicrograph variants. For EELS / EDS: HyperSpy (open Python), EDAX TEAM Pegasus, Bruker Esprit.

EBSD analysis — Oxford AZtecCrystal, EDAX TEAM EBSD / OIM Analysis, Bruker QUANTAX CrystAlign, MTEX (open MATLAB), DREAM.3D (BlueQuartz, open).

Atom probe analysis — CAMECA IVAS, APsuite (open).

FTIR / Raman analysis — OMNIC (Thermo), OPUS (Bruker), Renishaw WiRE, HORIBA LabSpec, KnowItAll, Spectragryph (free).

XPS analysis — CasaXPS (Casa Software), Thermo Avantage, Kratos ESCApe, ULVAC-PHI MultiPak, SpecsLab Prodigy, Avantage cloud, IGOR Pro.

Tomography — Avizo / Amira (Thermo Fisher), Dragonfly (ORS / Comet), VG Studio Max (Volume Graphics), 3D Slicer (open, medical-origin).

Phase-field / microstructure — DREAM.3D, MOOSE / PRISMS-PF, MICRESS.

Database services — ICDD PDF-5+, ICSD, CSD, NIST XPS database, MaterialsProject.org, AFLOW.org, OQMD.

13. Cross-references

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