High-Entropy Alloys and Nanomaterials

Tier 3 family index covering high-entropy alloys (HEAs), compositionally complex alloys (CCAs), and the full hierarchy of engineered nanomaterials from 0D quantum dots through 3D mesoporous solids. These materials sit outside the classical alloy-design and bulk-ceramic toolkits and have their own production routes, characterization needs, and supplier ecosystems.

1. High-Entropy Alloys — history and definition

1.1 Independent dual discovery (2004)

Two papers appeared in the same year, neither citing the other in submission, that established HEAs as a distinct alloy class:

• Yeh et al., Advanced Engineering Materials 6 (5), 299-303 (May 2004) — “Nanostructured High-Entropy Alloys with Multiple Principal Elements.” Coined the term “high-entropy alloy” and proposed configurational entropy as the design principle.
• Cantor et al., Materials Science and Engineering A 375-377, 213-218 (July 2004) — “Microstructural development in equiatomic multicomponent alloys.” Reported the now-canonical CoCrFeMnNi equiatomic FCC alloy (the “Cantor alloy”) that became the most-studied composition.

1.2 Compositional definition

The conventional definition: at least 5 principal elements, each present at 5 to 35 atomic %. Configurational entropy of mixing for an n-component equiatomic solid solution:

S_config = R · ln(n)

For n = 5, S_config = 1.61 R = 13.4 J·mol⁻¹·K⁻¹ — comparable to the latent entropy of melting for many metals, large enough (per the original hypothesis) to stabilize a single solid-solution phase against ordered intermetallics at moderate temperature.

1.3 The four core effects (and current debate)

The 2004-era HEA literature postulated four effects that distinguish HEAs from conventional alloys:

1. High configurational entropy — stabilizes random solid solution phases.
2. Severe lattice distortion — each atom sees a different local environment because every neighbor is a different element; this distortion strengthens the lattice and slows dislocation motion.
3. Sluggish diffusion — vacancy hopping requires statistically improbable favorable local configurations; diffusion coefficients are reduced 1-2 orders of magnitude vs. dilute alloys (debated; recent tracer measurements show the effect is smaller than originally claimed).
4. Cocktail effect — the combined property is not a simple weighted average; synergistic interactions yield unexpected behaviors (e.g. fracture toughness rising as T falls in the Cantor alloy).

Modern view (post-2018): effects 1 and 2 are real but smaller than originally claimed; many “HEAs” do not in fact form single-phase solid solutions and instead form duplex or multi-phase microstructures. The term compositionally complex alloy (CCA) is increasingly preferred as the broader, more honest descriptor.

2. Major HEA families

2.1 Cantor alloy CoCrFeMnNi (FCC)

The reference single-phase FCC HEA. Ductile down to 77 K (liquid nitrogen) with toughness rising with decreasing temperature — opposite to the ductile-to-brittle transition of conventional steels. Gludovatz et al., Science 345, 1153-1158 (Sep 2014), measured K_JIc > 200 MPa·m^0.5 at 77 K. Mechanism: deformation switches from dislocation slip at room temperature to nanotwinning at cryogenic T, providing additional work-hardening capacity.

2.2 AlCoCrFeNi family (BCC and duplex)

Adding aluminum shifts the structure from FCC to BCC as Al content rises. AlCoCrFeNi with x = 0.7-1.0 is BCC with very high strength (yield > 1.5 GPa) but limited ductility (< 5% elongation). Eutectic high-entropy alloys (EHEAs) — Lu et al., Scientific Reports 4, 6200 (Aug 2014), AlCoCrFeNi2.1 — exhibit a fine lamellar FCC+BCC eutectic with simultaneous high strength (1.2 GPa) and ductility (15-20% elongation), addressing the classical strength-ductility tradeoff.

2.3 Refractory HEAs (Senkov class)

Senkov and Wilks at AFRL (Wright-Patterson) introduced refractory HEAs in Intermetallics 18 (9), 1758-1765 (Sep 2010):

• MoNbTaW and MoNbTaVW — BCC; retain yield strengths > 400 MPa at 1600 °C, the temperature range where Ni-based superalloys melt (~1350 °C). Targeted at turbine and hypersonic vehicle applications.
• HfNbTaTiZr — BCC single-phase; ductile at room temperature (~20% elongation); the most workable refractory HEA.
• HfNbZrTi — BCC; biomedical interest (no Ni, no Co — both allergenic).

2.4 Lightweight HEAs

Density-reduced HEAs replacing transition metals with Al + Li + Mg + Sc + Ti. Examples: Al20Li20Mg10Sc20Ti30 (Youssef 2015) — density 2.67 g·cm⁻³ (vs. ~8 g·cm⁻³ for Cantor), microhardness 4.9-5.8 GPa.

2.5 TWIP and TRIP HEAs

• TWIP (twinning-induced plasticity) — Fe40Mn40Co10Cr10; mechanical twinning provides additional hardening on top of dislocation slip; total elongation > 70%.
• TRIP (transformation-induced plasticity) — metastable FCC transforms to HCP under strain, providing strain-hardening; Fe50Mn30Co10Cr10 (Li-Pradeep-Deng-Tasan-Raabe, Nature 534, 227-230, Jun 2016).

2.6 Eutectic HEAs

EHEAs (see 2.2) exploit eutectic solidification to produce fine 2-phase composites in a single casting step. AlCoCrFeNi2.1 remains the benchmark; CoCrFeNi-X variants with Nb, Mo, or Hf are being developed for additive manufacturing.

2.7 High-entropy ceramics

• High-entropy oxides — (Mg,Co,Ni,Cu,Zn)O rock-salt structure (Rost-Maria-Sarkar 2015); (HfO2-ZrO2-CeO2-Y2O3-La2O3) fluorite for thermal barrier coatings.
• High-entropy borides — (Hf,Zr,Ti,Ta,Nb)B2 — AIM ultra-high temperature ceramic; oxidation resistance > 1800 °C.
• High-entropy carbides — (Hf,Zr,Ti,Ta,Nb)C — Sarker-Harrington-Toher-Curtarolo entropy-stabilized 2018; hardness ~30 GPa.
• High-entropy nitrides — (TiVCrZrHf)N — magnetron-sputtered hard coatings.

3. Compositionally complex alloys (CCAs)

CCAs is the broader umbrella term that includes:

• HEAs with truly random single-phase solid solutions
• Medium-entropy alloys (MEAs) — 3-4 principal elements (e.g. CoCrNi, CoCrFeNi)
• Compositionally complex multi-phase alloys (intentionally non-single-phase, designed via CALPHAD)

The shift from “HEA” to “CCA” reflects the recognition that single-phase status is the exception rather than the rule, and that multi-phase architectures often have better properties.

4. Production routes

Route	Typical lot	Notes
Arc melting	5-500 g	Lab-scale; chilled Cu hearth under Ar; rapid solidification but as-cast inhomogeneity
Induction melting	100 g - 10 kg	Pilot-scale; can use cold crucible to avoid contamination
Mechanical alloying	10-1000 g	Ball milling of elemental powders 20-60 h; fine grain (nanocrystalline) but oxygen pickup
Spark plasma sintering (SPS)	10-500 g pellets	Consolidates milled powder at 800-1200 °C, 50-100 MPa, 5-30 min; preserves nanocrystalline microstructure
Additive manufacturing — LPBF	parts to 500 mm	Laser powder bed fusion; rapid solidification (10⁵-10⁶ K·s⁻¹); enables non-equilibrium HEA compositions; main vehicle for HEA scale-up
Additive manufacturing — DED	parts to 2 m	Directed energy deposition; lower resolution than LPBF but allows in-situ compositional variation (FGM functionally-graded materials)
Suction casting	10-100 g	Lab; pulls melt into Cu mold; high cooling rate
Twin-roll strip casting	ribbon	Continuous; rapid quench

5. HEA databases

• NIST HEA Database — open; ~7,500 compositions with measured phase + property data.
• Materials Project HEA module (LBNL) — DFT-computed formation energies, phase predictions.
• MaterialsZone (commercial, Israel) — proprietary HEA database with ML-driven composition search.
• Citrine Informatics — commercial alloy informatics platform; HEA partner program.
• TCHEA5 (Thermo-Calc Software) — CALPHAD database specifically for HEAs.

6. HEA applications

• Cryogenic structural — LNG containment and tanker piping; Cantor alloy and FeCoNiMn lower-Co variants retain toughness at LNG service temperature (~111 K = -162 °C).
• High-temperature turbines — Senkov refractory HEAs target above the ~1350 °C Ni-superalloy ceiling; not yet certified for service.
• Nuclear — Zhang et al., Nature Communications 6, 8736 (Oct 2015), showed irradiation-induced defect clustering is delayed in HEAs because the chemically disordered lattice provides many local sink configurations; pursued by GE and Westinghouse for Gen-IV reactor cladding.
• Biomedical — Ti-Zr-Nb-Ta-Mo HEAs as Ni-free, Co-free implant alloys; lower elastic modulus (closer to bone) than Ti-6Al-4V.
• Wear and corrosion-resistant coatings — laser-clad CoCrFeNiMo on tool steels; AlCoCrFeNiCu on slurry pump impellers.
• Catalysis — high-entropy nanoparticle catalysts (Yao-Hu-Pan-Hu-Hong-Li-Wang-Wang 2018; carbothermal shock synthesis of HEA NPs) for ammonia decomposition, oxygen evolution.

7. Nanomaterials by dimensionality

A nanomaterial has at least one dimension < 100 nm. Properties diverge from bulk because surface-to-volume ratio dominates and quantum confinement becomes accessible.

7.1 0D — quantum dots and quantum confinement

Brus (Bell Labs, 1984) first showed semiconductor nanocrystal absorption edges blue-shift with decreasing diameter — the optical signature of quantum confinement. Murray, Norris, Bawendi at MIT (JACS 1993) developed the hot-injection synthesis of size-monodisperse CdSe quantum dots that is still the basis of modern colloidal-QD chemistry.

Standard QD families:

• CdSe / CdSe-ZnS core-shell — visible (450-650 nm) emission; PLQY > 90%; CdSe is RoHS-restricted in many markets.
• InP / InP-ZnS — cadmium-free; visible emission; lower PLQY than CdSe historically but now > 80% (Nanosys, Najing Tech).
• PbS, PbSe — near-IR / shortwave-IR (900-1600 nm); IR sensing and SWIR imaging (SWIR Vision Systems Acuros sensor).
• Perovskite QDs — CsPbBr3, CsPbCl3, CsPbI3; very high PLQY (often > 95%) but halide migration and stability issues. See mof-cof-perovskite-catalog for perovskite chemistry.
• Carbon dots — fluorescent ~2-10 nm graphitic; benign chemistry; lower PLQY (10-40%).

Display commercialization — QD-enhanced LCDs use a blue LED backlight with red+green QD color converter:

• Samsung QD-OLED (2022+) — blue OLED + red/green QD color converter; competitor to LG WOLED.
• Sony BRAVIA XR A95L — Samsung Display QD-OLED panel.
• LG QNED — Mini-LED + QD enhancement film (not OLED-based).
• TCL Mini-LED with QD — QDEF (quantum dot enhancement film, Nanosys / Shoei Chemical).

Nobel Prize 2023 — Bawendi (MIT), Brus (Columbia), Ekimov (Nanocrystals Tech.) for the discovery and synthesis of quantum dots.

7.2 1D — nanowires, nanorods, nanotubes (non-CNT)

• Si nanowires — Lieber group at Harvard (Cui-Lieber 2001); VLS (vapor-liquid-solid) growth using Au catalyst droplets; field-effect biosensors (label-free detection of viruses, proteins, DNA).
• ZnO nanorods — hydrothermal growth on Si or glass; piezoelectric harvesting (Wang, Georgia Tech, “nanogenerator” 2006); UV detectors.
• GaN nanowires — bottom-up LED structures; lower threading dislocation density than planar GaN; addressable for micro-LED.
• CdSe nanorods — polarized emission; LCD backlight.
• Au nanorods — plasmonic; aspect ratio tunes longitudinal plasmon from 600-1100 nm; photothermal therapy (Halas, Rice); SERS substrates.
• Ag nanowires — transparent conductive films (Cambrios ClearOhm, C3Nano); flexible touch screens and OLED transparent electrodes; competitor to ITO.

7.3 1D — carbon nanotubes (CNTs)

Discovery:

• MWCNT — Iijima, Nature 354, 56-58 (Nov 1991); multi-wall carbon nanotube; concentric graphene cylinders.
• SWCNT — Iijima and Ichihashi 1993 (independent of Bethune-Kiang-de Vries 1993); single graphene cylinder.
• DWCNT — double-wall; properties between SWCNT and MWCNT.

Chirality and electronic structure: a SWCNT is specified by integers (n,m) defining the rollup vector. If (n-m) mod 3 = 0, the tube is metallic; otherwise semiconducting. (6,5) is the most common semiconducting tube in sorted samples (~1.2 nm diameter, 1.27 eV bandgap). Diameter is ~0.083·√(n²+nm+m²) nm.

Production:

• HiPco (High-Pressure CO disproportionation; Smalley, Rice) — Fe carbonyl catalyst; SWCNTs ~0.8-1.2 nm; historic but now low-volume.
• CoMoCAT — Co-Mo silica-supported catalyst; narrow chirality distribution; SouthWest NanoTechnologies (now Chasm Advanced Materials).
• CVD — most common at scale; CoMo or Fe-Mo catalysts on Al2O3 or SiO2; C2H4 / C2H2 / CH4 feedstock; CCVD (catalytic chemical vapor deposition).
• Floating-catalyst CVD — ferrocene + thiophene + CH4 + H2; produces direct-spun CNT fibers (Tortoise / Nanocomp).
• Arc-discharge — historic; produces MWCNTs with crystalline graphite shells.

Suppliers (commercial scale):

• OCSiAl — Tuball SWCNT; Luxembourg / Russia; world’s largest SWCNT producer (~75-100 t·yr⁻¹).
• Cnano (China) — MWCNT; ~30,000 t·yr⁻¹ capacity for battery additives.
• LG Chem — MWCNT 1,700 t·yr⁻¹ for in-house battery cathode use.
• Arkema Graphistrength — MWCNT for conductive plastics.
• Showa Denko VGCF — vapor-grown carbon fiber (intermediate between CNT and carbon fiber).
• Nanocyl — Belgium; MWCNT NC7000 for conductive composites and ESD.
• Cabot Corporation — acquired DM Materials; CNT and graphene additives.

Applications:

• Li-ion battery conductive additive — primary commercial application; Nanocyl, OCSiAl Tuball, LG Chem; 0.5-2 wt% SWCNT in NMC811 cathode replaces 2-5 wt% carbon black, raising energy density.
• Conductive films and yarns — Tortoise Materials; Lintec; CNT yarn shielding cables (NASA, US Army).
• Composites — Toray T-CCT prepregs; Mitsubishi Rayon; CNT-toughened CFRP for aerospace secondary structures.
• Transistors — IBM 2017 demonstrated CNT FET at sub-10-nm node; long-term CMOS replacement candidate but contact resistance and chirality purity remain blockers.

7.4 2D — graphene and beyond

Graphene — single sheet of sp²-hybridized carbon, honeycomb lattice; thickness 0.34 nm; zero-bandgap semimetal with Dirac-cone band structure; Young’s modulus ~1 TPa, electrical mobility > 200,000 cm²·V⁻¹·s⁻¹ (suspended).

Discovery: Geim and Novoselov, Science 306, 666-669 (Oct 2004) — Scotch-tape mechanical exfoliation of HOPG. Nobel Prize Physics 2010.

Production methods:

• Mechanical exfoliation — lab only; not scalable.
• LPE liquid-phase exfoliation — Coleman (Trinity College Dublin); shear-mixing graphite in NMP or aqueous surfactant; few-layer graphene flakes at gram scale; First Graphene, Versarien, Talga, Graphenea also use variants.
• CVD on Cu foil — Ruoff (UT Austin) 2009; methane + hydrogen at 1000 °C; single-layer continuous film transferable to target substrate; Manchester, Cambridge, Graphenea, 2D Carbon Tech, Bluestone Global Tech.
• Epitaxial graphene on SiC — sublimation of Si from SiC(0001) at 1500 °C in Ar; wafer-scale single-layer graphene for high-frequency electronics; Graphensic (Sweden).
• Reduced graphene oxide (rGO) — Hummers’ method to oxidize graphite, exfoliate to GO, then chemically or thermally reduce; defective but cheapest at scale; The Sixth Element, Standard Graphene.

Commercial suppliers: First Graphene (Australia), Graphenea (Spain), Versarien (UK), LG Chem (Korea), Standard Graphene, 2D Materials Pte (Singapore), Talga (Sweden), Cabot Corp, Nanografi.

Applications:

• Conductive composites — graphene-loaded epoxy for lightning-strike protection on CFRP aerostructures (Haydale, First Graphene).
• Barrier coatings — graphene + polymer multilayer for water vapor transmission rate (WVTR) < 10⁻³ g·m⁻²·d⁻¹; OLED encapsulation candidate.
• Battery and supercapacitor electrodes — graphene-rich composite electrodes with higher rate capability.
• Heat spreader — laminate graphene films (Kaneka Graphene); thermal conductivity in-plane ~1500-1900 W·m⁻¹·K⁻¹.

Hexagonal boron nitride (hBN) — insulator analogue of graphene; bandgap ~6 eV; clean dielectric substrate for 2D-material devices (lower charge-impurity scattering than SiO2); thermal substrate.

Transition-metal dichalcogenides (TMDC) — MX2 with M = Mo, W, Re; X = S, Se, Te. Bandgap 1.2-2.0 eV; direct in monolayer (indirect in bulk). MoS2, WS2, MoSe2, WSe2, MoTe2 are most studied. Wang-Kis at EPFL (Nature Nanotechnology 6, 147-150, Mar 2011) demonstrated the first MoS2 monolayer transistor with mobility ~200 cm²·V⁻¹·s⁻¹ and on/off ratio 10⁸.

Phosphorene — single layer of black phosphorus; puckered honeycomb; bandgap thickness-tunable 0.3-2.0 eV; Li-Xia (Fudan / Vanderbilt) 2014.

Other 2D allotropes — silicene, germanene, stanene (heavier group-IV analogues — substrate-stabilized only); borophene (Mannix, Northwestern 2015).

MXenes — Gogotsi and Barsoum at Drexel (Advanced Materials 23 (37), 4248-4253, Oct 2011); MAX-phase precursor (e.g. Ti3AlC2) etched with HF to remove the A-layer, leaving Ti3C2Tx 2D carbide with surface terminations T_x (-O, -OH, -F). Over 30 compositions: Ti2CTx, V2CTx, Nb2CTx, Mo2CTx, etc. Metallic; very high volumetric capacitance for supercapacitors; EMI shielding (single 45-nm-thick film attenuates > 90 dB), electrocatalysis, water purification. Commercial: Murata, MXene Inc., Y-Carbon.

7.5 3D — porous and aerogel nanomaterials

Aerogels — Kistler, Nature 1931; silica aerogel synthesized by supercritical drying of a wet gel. Density < 0.1 g·cm⁻³; thermal conductivity 12-18 mW·m⁻¹·K⁻¹ (lower than still air).

• Aspen Aerogels (Northborough, MA) — production-scale silica aerogel blankets:
  • Cryogel Z — for cryogenic and LNG service; 5 and 10 mm thick.
  • Pyrogel XTE / XTF — for industrial high-T (up to 650 °C continuous).
  • Spaceloft — building envelope; 5 and 10 mm.
• Cabot Aerogel — discontinued aerogel particle product line (Lumira) in 2020; aerogel returned to Aspen as primary supplier.
• Graphene aerogel — ultralight (~3 mg·cm⁻³); compressible; energy absorption; Bao-Marsh (LLNL).
• CNT aerogel — direct-spun multi-walled CNT sheets and felts.
• Cellulose nanofiber aerogel — biodegradable insulation; Stora Enso pilot.

Ordered mesoporous oxides — Beck, Kresge et al. at Mobil Oil (Nature 359, 710-712, Oct 1992) — surfactant template-directed synthesis of MCM-41 (hexagonal channels, pore 1.5-10 nm) and MCM-48 (cubic). Zhao, Stucky et al. at UCSB (1998) — SBA-15 (Pluronic P123 surfactant; hexagonal; pore 5-30 nm; thicker walls).

Applications: catalyst supports, drug delivery, controlled release. Commercial: Sigma-Aldrich, Glantreo, MCMaterials.

8. Nano-fabrication and patterning

• ALD atomic layer deposition — Suntola (Finland) 1977; self-limiting surface reactions; Å-level thickness control; conformal on high-aspect-ratio features. Mainstream for high-k gate oxides (HfO2, ZrO2), DRAM trench capacitor, 3D NAND oxide-nitride stacks, OLED encapsulation, MEMS coatings. See deposition tools in refractory-and-thin-film-deposition.
• MBE molecular beam epitaxy — ultra-high vacuum (10⁻¹⁰ Torr) effusion-cell sources; Å-monolayer epitaxial growth of III-V, II-VI, oxide superlattices. Veeco GENxplor R&D, GEN200 6”-wafer production, GEN3000 200 mm production.
• CVD — see refractory-and-thin-film-deposition.
• EBL electron-beam lithography — Raith eLINE Plus, JEOL JBX-9500FS, Vistec EBPG5200; resolution ~10 nm in PMMA on HSQ; slow (serial); used for photomask fabrication and research patterning.
• FIB-SEM focused ion beam scanning electron microscopy — Zeiss Crossbeam 550 / 350, FEI Helios, Tescan Solaris; Ga+ ion mill for cross-section and TEM lamella prep; 5-10 nm precision; also direct-write of nanostructures.
• Two-photon lithography — Nanoscribe Photonic Professional GT2 and Quantum X; 780 nm fs laser; voxel ~150 nm lateral × 500 nm axial; arbitrary 3D structures up to mm scale; photonic crystals, microfluidics, scaffolds.
• DUV and EUV stepper lithography — covered in design-semiconductor-lithography-stepper under Engineering family.
• Nanoimprint lithography (NIL) — Canon FPA-1200NZ2C and EV Group EVG770 NT; replica molding for high-volume nano-patterning at HDD media plant scale.

9. Suppliers (research-scale nanomaterials)

Vendor	Specialty
Sigma-Aldrich (Merck)	Broadest catalog; nanoparticles, QDs, MOFs, 2D materials
Strem Chemicals (Ascensus)	Organometallics, precursors for ALD/MOCVD
Nanocs	Conjugation-grade nanoparticles
American Elements	Custom nanoparticles, oxides
MKnano	Carbon nanomaterials, BN, MoS2
Inframat	Oxides, nitrides nanopowders
US Research Nanomaterials	Nanopowders, dispersions
Skyspring Nanomaterials	Generalist
Tokyo Chemical Industry (TCI)	Organic and organometallic precursors
ACS Material	2D materials, MXenes, graphene

Carbon black and fumed silica (bulk amorphous nanomaterials)

• Cabot Corp — Vulcan, Black Pearls (carbon black); Cab-O-Sil (fumed silica); fumed alumina; tantalum oxide powders for capacitors.
• Evonik (Degussa) — AEROSIL fumed silica; AEROXIDE fumed alumina; AERODISP dispersions.
• Wacker Chemie — HDK fumed silica.
• Birla Carbon, Orion Engineered Carbons, Tokai Carbon — carbon black supply.

Quantum dot suppliers

• Nanosys (now Shoei Chemical, acquired 2023) — QDEF film for displays.
• Najing Tech (China) — InP QDs for cadmium-free displays.
• Mesolight — CdSe and InP.
• Quantum Materials Corp. — perovskite and CdSe.
• Nanoco Group (UK) — cadmium-free heavy-metal-free QDs.
• UbiQD — agricultural QD films.

CNT suppliers (commercial scale)

OCSiAl Tuball, Cnano, LG Chem, Arkema, Nanocyl, Showa Denko, Cabot, Hyperion, Bayer (legacy), Carbon Solutions (research).

Graphene suppliers (commercial scale)

First Graphene, Graphenea, Versarien, Talga, Standard Graphene (Korea), The Sixth Element (China), 2D Materials Pte (Singapore), LG Chem, Cabot (rGO).

Aerogel

Aspen Aerogels (Cryogel, Pyrogel, Spaceloft), Active Aerogels, JIOS Aerogel, Enersens.

10. Characterization gaps specific to HEAs and nanomaterials

• Local chemistry resolution — APT atom-probe tomography (CAMECA LEAP 5000XR) at sub-nm and single-atom chemical resolution; the only technique that can directly visualize chemical short-range order in an HEA. See characterization-techniques-deep.
• Single-particle ICP-MS — sp-ICP-MS for nanoparticle size distribution down to 5 nm at trace concentration (PerkinElmer NexION 5000, Agilent 7900 in sp-mode).
• DLS dynamic light scattering — Malvern Zetasizer Pro / Ultra; hydrodynamic diameter 0.3 nm to 10 µm.
• SAXS small-angle X-ray scattering — Anton Paar SAXSpoint 5.0, Xenocs Xeuss 3.0; structural information 1-100 nm; complements TEM for ensemble statistics.
• AFM atomic force microscopy — Bruker Dimension Icon, Park NX-Hivac; topography and modulus mapping at sub-nm.
• Nanoindentation — Bruker Hysitron TI 980, Keysight G200 NanoIndenter; hardness and modulus at depths < 100 nm; essential for thin films and HEA single-grain mechanics.

Adjacent notes

• mof-cof-perovskite-catalog — porous crystalline materials and hybrid organic-inorganic systems.
• magnetic-and-optical-materials — soft and hard magnets, photonic materials.
• refractory-and-thin-film-deposition — high-T ceramics and deposition equipment used for nanomaterials.
• characterization-techniques-deep — APT, TEM, EBSD, XRD, XPS workflows for HEA and nano analysis.
• metallurgy-and-alloys — conventional alloy design context.
• ceramics-and-glasses — bulk ceramics adjacent to high-entropy ceramics.
• semiconductor-materials — Si, SiC, GaN, InP semiconductors; QD and 2D-material devices.
• design-semiconductor-lithography-stepper — DUV and EUV patterning.