Research method
X-ray Diffraction (XRD)
30 studies
X-ray diffraction records how a periodic solid scatters X-rays into angles set by the lattice. Single-crystal XRD gives atom positions, space group and disorder; powder XRD (PXRD) fingerprints a phase and, for nanoparticles, a short list of peak positions that can match an fcc metal. In this library those two experiments are used for three different claims: a coordination geometry, a single-crystal-to-single-crystal ligand swap, and confirmation that a colloid is metallic silver or platinum.
Chemists reach for XRD when the question is which lattice formed and where the atoms sit. It answers 'what crystalline phase is this?' Its main limitation is that a powder pattern of nanoparticles is not a full molecular structure, a high R-factor after a solid-state reaction is not an industrial turnover number, and a band gap computed beside a crystal structure is not an optical measurement on a device.
Studies
30
Findings
5
7 supporting · 0 challenging · 0 qualifying citations
Open tensions
2
Currently
What we know
- Single-crystal XRD can lock a coordination geometry that powder methods only corroborate. A Zn phenanthroline–maleate hydrate is distorted square pyramidal in triclinic P-1; Hirshfeld surfaces are 30.6% H···O/O···H contacts and 9.0% C···C π-stacking. Periodic-DFT on that lattice gives a 3.45 eV gap — a computed number, not a measured spectrum — and the antibacterial MIC against S. mutans is 1000 μg/mL, far weaker than gentamicin.
- Single-crystal-to-single-crystal XRD can watch a lattice stay crystalline while catalysis turns over. In solid rhodium organometallics, ethene substitution of a token NBA ligand gives an octahedral anion cage; the hexagonal porous polymorph (25% void) reaches TOF(90%) = 1160 h⁻¹ versus 20–29 h⁻¹ for nonporous crystals. Solution lifetimes are minutes, post-substitution R-factors are high, and industrial TON still trails silica-supported systems.
- Powder XRD of silver colloids is a phase fingerprint, not a molecular structure. Blackberry-leaf Ag nanoparticles show peaks at 38.1°, 44.4°, 54.5° and 77.9° with TEM diameters 50–120 nm and SPR at 449 nm. Glutathione-capped Ag stirred at 60 °C is fcc; TEM diameters grow 3.20 → 4.83 → 6.19 nm at 36, 48 and 72 h while SPR sits at 344–354 nm.
- XRD/TEM size of a fuel-cell catalyst need not match which particles do the electrochemistry. Platinum sputtered onto PEG starts as 1.8 nm primaries; heat treatment at 150 °C on Vulcan carbon yields a bimodal 2.5 ± 0.8 nm and 6.7 ± 1.8 nm distribution, and the larger population dominates oxygen-reduction activity. Gamma-made Ag, Se and Ag–Se particles average 10.95, 20.54 and 12.69 nm by complementary sizing, with UV-vis maxima at 406, 518 and 420 nm — XRD here is one size/phase check among several.
- For an unusual molecular crystal, SC-XRD reports isomer populations that NMR then names. Arylhalodiphosphene 8·(Et₂O)₂ is 85% E / 15% Z in the solid with E/Z disorder; ³¹P signals at 433 and 502 ppm (¹JPP = 574 Hz) confirm P=P. Computed E-8* is 2.96 kcal mol⁻¹ more stable than Z-8*. Halide abstraction still does not isolate a free diphosphadiazonium salt.
Largest unresolved question
A powder pattern of a colloid and a single-crystal structure of a molecule are not the same XRD experiment. Fcc Ag peaks at 38.1–77.9° identify a metal phase and roughly a size regime; they do not give a coordination number, a space group of a molecular hydrate, or an E/Z ratio. Quoting 'XRD confirmed the structure' without saying powder versus single-crystal erases that.
Procedure
How it works
The main stages of the method. Specific protocols and analysis choices vary between studies.
Prepare a crystalline sample
Single-crystal work needs a crystal large enough to mount; powder XRD needs a polycrystalline solid, often a nanoparticle pellet or dried colloid. Amorphous material and most capping ligands will not contribute Bragg peaks.
Illuminate with X-rays
A beam of known wavelength hits the sample. Periodic planes scatter constructively only at angles set by their spacing (Bragg's law). The pattern is a geometric fingerprint of the lattice, not a photograph of molecules in solution.
Record angles and intensities
A detector measures where the diffracted beams land and how strong they are. For powders this is a list of peak positions; for a single crystal it is a three-dimensional intensity set from which a structure can be solved.
Index the phase or solve the structure
Powder peaks are matched to a known phase (for example fcc silver) and sometimes a Scherrer size. Single-crystal data yield atom positions, space group, and disorder. A nanoparticle powder pattern is not equivalent to a molecular crystal structure.
Do not treat the lattice as purity or a device test
XRD answers which crystalline phase formed and, for SC-XRD, where the atoms sit. Matching fcc metal does not prove a pure colloid; a high R-factor after a solid-state reaction is not a turnover number; a band gap computed beside the structure is not an optical measurement on a device.
Common misconceptions
An XRD pattern that matches fcc silver proves the sample is pure Ag.
Peak positions identify a crystalline metal phase. Capping ligands, residual extract, and amorphous material are largely invisible. The blackberry Ag work still needs TEM/EDX (~90% Ag at 3 keV) and does not assign a full capping-molecule structure; GSH-capped particles still grow more polydisperse with stirring time.
If XRD gives a crystal structure, the computed band gap and the docking scores are also measurements.
The Zn paper's 3.45 eV gap is periodic-DFT on the lattice, and docking ΔG values are computational. Optical/electronic device tests were not done; antibacterial MIC 1000 μg/mL is a separate wet assay, not an XRD result.
A diffractogram of nanoparticles is equivalent to a single-crystal structure of a molecule.
NP powder peaks report a metal phase and a Scherrer-type size scale. The diphosphene and Zn papers use SC-XRD for atom positions, disorder (85% E / 15% Z) and packing; those coordinates are what a powder Ag pattern does not contain.
Related
Claim ledger
What the evidence shows
Drawn from 30 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.
Single-crystal XRD can lock a coordination geometry that powder methods only corroborate. A Zn phenanthroline–maleate hydrate is distorted square pyramidal in triclinic P-1; Hirshfeld surfaces are 30.6% H···O/O···H contacts and 9.0% C···C π-stacking. Periodic-DFT on that lattice gives a 3.45 eV gap — a computed number, not a measured spectrum — and the antibacterial MIC against S. mutans is 1000 μg/mL, far weaker than gentamicin.
Single-crystal-to-single-crystal XRD can watch a lattice stay crystalline while catalysis turns over. In solid rhodium organometallics, ethene substitution of a token NBA ligand gives an octahedral anion cage; the hexagonal porous polymorph (25% void) reaches TOF(90%) = 1160 h⁻¹ versus 20–29 h⁻¹ for nonporous crystals. Solution lifetimes are minutes, post-substitution R-factors are high, and industrial TON still trails silica-supported systems.
Powder XRD of silver colloids is a phase fingerprint, not a molecular structure. Blackberry-leaf Ag nanoparticles show peaks at 38.1°, 44.4°, 54.5° and 77.9° with TEM diameters 50–120 nm and SPR at 449 nm. Glutathione-capped Ag stirred at 60 °C is fcc; TEM diameters grow 3.20 → 4.83 → 6.19 nm at 36, 48 and 72 h while SPR sits at 344–354 nm.
- Blackberry-leaf silver nanoparticles against plant pathogens
- Stirring time sets GSH-capped silver nanoparticle size
Study Role Design N Population Outcome Blackberry-leaf silver nanoparticles against plant pathogens Supports Animal / in-vitroPlant-extract AgNP synthesis with antibacterial titration against plant pathogens and DPPH assays Materials/antimicrobial assay study — no sample N Ralstonia solanacearum and Erwinia carotovora cultures exposed to Rubus-derived AgNPs Pathogen inhibition and antioxidant activity of biogenic AgNPs Stirring time sets GSH-capped silver nanoparticle size Supports OtherTime-dependent glutathione-capped AgNP growth tracked by SPR/TEM/XRD Nanomaterial synthesis kinetics — no sample N Silver nanoparticles prepared with glutathione at 60 °C Stirring-time dependence of particle diameter and SPR XRD/TEM size of a fuel-cell catalyst need not match which particles do the electrochemistry. Platinum sputtered onto PEG starts as 1.8 nm primaries; heat treatment at 150 °C on Vulcan carbon yields a bimodal 2.5 ± 0.8 nm and 6.7 ± 1.8 nm distribution, and the larger population dominates oxygen-reduction activity. Gamma-made Ag, Se and Ag–Se particles average 10.95, 20.54 and 12.69 nm by complementary sizing, with UV-vis maxima at 406, 518 and 420 nm — XRD here is one size/phase check among several.
- Sputtering Pt onto PEG to make fuel-cell catalysts
- Gamma-made Ag–Se nanoparticles carrying cefotaxime
Study Role Design N Population Outcome Sputtering Pt onto PEG to make fuel-cell catalysts Supports OtherHeat-treated Pt nanoparticle catalyst layers with bimodal size distribution for ORR Electrocatalysis materials characterization — no sample N Carbon-supported platinum nanoparticle fuel-cell catalyst layers ORR activity contribution of larger vs smaller Pt particle populations Gamma-made Ag–Se nanoparticles carrying cefotaxime Supports Animal / in-vitroRadiolytic synthesis of Ag, Se, and Ag–Se nanoparticles loaded with cefotaxime for antimicrobial/antibiofilm assays Particle characterization and multi-organism assays rather than a single sample N Bacterial cultures in antimicrobial and antibiofilm tests Cefotaxime-loaded Ag–Se nanoparticles show synergistic antimicrobial and antibiofilm activity with membrane-leakage evidence For an unusual molecular crystal, SC-XRD reports isomer populations that NMR then names. Arylhalodiphosphene 8·(Et₂O)₂ is 85% E / 15% Z in the solid with E/Z disorder; ³¹P signals at 433 and 502 ppm (¹JPP = 574 Hz) confirm P=P. Computed E-8* is 2.96 kcal mol⁻¹ more stable than Z-8*. Halide abstraction still does not isolate a free diphosphadiazonium salt.
Debates
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.
A powder pattern of a colloid and a single-crystal structure of a molecule are not the same XRD experiment. Fcc Ag peaks at 38.1–77.9° identify a metal phase and roughly a size regime; they do not give a coordination number, a space group of a molecular hydrate, or an E/Z ratio. Quoting 'XRD confirmed the structure' without saying powder versus single-crystal erases that.
A powder pattern of a colloid and a single-crystal structure of a molecule are not the same XRD experiment. Fcc Ag peaks at 38.1–77.9° identify a metal phase and roughly a size regime; they do not give a coordination number, a space group of a molecular hydrate, or an E/Z ratio. Quoting 'XRD confirmed the structure' without saying powder versus single-crystal erases that.
- Blackberry-leaf silver nanoparticles against plant pathogens
- A new Zn phenanthroline–maleate crystal
- Isolating rare arylhalodiphosphene P=P–X bonds
Study Role Design N Population Outcome Blackberry-leaf silver nanoparticles against plant pathogens Supports Animal / in-vitroPlant-extract AgNP synthesis with antibacterial titration against plant pathogens and DPPH assays Materials/antimicrobial assay study — no sample N Ralstonia solanacearum and Erwinia carotovora cultures exposed to Rubus-derived AgNPs Pathogen inhibition and antioxidant activity of biogenic AgNPs A new Zn phenanthroline–maleate crystal Supports OtherCrystal structure, periodic DFT, and secondary MIC assays of a Zn–phenanthroline–maleate complex Coordination-chemistry characterization — no cohort N Zn(II) phenanthroline/maleate coordination compound Structure, electronics, and weak antibacterial activity vs S. mutans Isolating rare arylhalodiphosphene P=P–X bonds Supports OtherSynthesis, SC-XRD, and DFT of thermally robust arylhalodiphosphenes and halide exchanges Main-group synthesis/structure study — no sample N Arylhalodiphosphene compounds and silver coordination complexes P=P bonding metrics and E/Z preferences across halide series
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
XRD can show a lattice that is not the working catalyst. The rhodium hexagonal polymorph's 25% void tracks a 1160 versus 20–29 h⁻¹ TOF split, but post-SC-SC R-factors are already high. On carbon-supported Pt, the particles XRD/TEM size (the 6.7 nm mode) are the ORR-active population, not the leftover 1.8 nm primaries. Structure of what was synthesised is not automatically structure of what turns over.
XRD can show a lattice that is not the working catalyst. The rhodium hexagonal polymorph's 25% void tracks a 1160 versus 20–29 h⁻¹ TOF split, but post-SC-SC R-factors are already high. On carbon-supported Pt, the particles XRD/TEM size (the 6.7 nm mode) are the ORR-active population, not the leftover 1.8 nm primaries. Structure of what was synthesised is not automatically structure of what turns over.
- Solid Rh crystals isomerize butene without dissolving
- Sputtering Pt onto PEG to make fuel-cell catalysts
Study Role Design N Population Outcome Solid Rh crystals isomerize butene without dissolving Supports OtherSolid/gas SC-SC organometallic substitutions and polymorphic catalysis of 1-butene isomerization Solid-state organometallic materials — no sample N Molecular organometallic crystals ([1-NBA]/[BArF4] ethene polymorphs) SC-SC reactivity and TOF differences between porous hexagonal and octahedral polymorphs Sputtering Pt onto PEG to make fuel-cell catalysts Supports OtherHeat-treated Pt nanoparticle catalyst layers with bimodal size distribution for ORR Electrocatalysis materials characterization — no sample N Carbon-supported platinum nanoparticle fuel-cell catalyst layers ORR activity contribution of larger vs smaller Pt particle populations
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
Timeline
How understanding moved
Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.
2026
- A new Zn phenanthroline–maleate crystal
- Isolating rare arylhalodiphosphene P=P–X bonds
Concept page published
X-ray Diffraction (XRD)
Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Coverage edits are distinct from reviewed research changes and corrections. Dates record PaperFren updates; study publication dates appear in the timeline.
- Coverage updated · Concept page published
Papers
30 studies in this library bear on X-ray Diffraction (XRD), ordered by citations.
- Single-atom Co–N–C catalyzes nitroarene azo coupling
A self-supporting Co–N–C single-atom catalyst with a CoN4C8-1-2O2 site hydrogenatively couples nitroarenes to azo compounds.
- Ir nanodendrites on ATO for acid OER
TTAB-grown Ir nanodendrites on mesoporous ATO outperform Ir black for oxygen evolution in acid and in a PEM electrolyzer.
- A copper porphyrin oxidizes water at low overpotential
A molecular Cu(II) porphyrin evolves O2 at 300–440 mV overpotential in neutral phosphate buffer with >93% faradaic efficiency.
- Unsymmetrical ligands still make one Pd2L4 cage isomer
Steric and geometric ligand design plus solvent polarity steer unsymmetrical dipyridyl ligands into a single cis or trans Pd2L4 cage rather than a statistical isomer mix.
- Bismuth oxyhalide films as photoelectrodes
AACVD BiOX films show halide-tuned bandgaps; untreated BiOBr gives about 0.38 mA cm−2 photoanodic current without a sacrificial donor.
- Ultrathin porous CoP nanosheets drive HER
Phosphidation of Co3O4 yields sub-1.1 nm porous CoP sheets with exposed {200} facets and high HER mass activity.
- Defect hydroxides in UiO-66 shuttle protons
Simulations of missing-linker UiO-66 put charge-balancing OH on under-coordinated Zr and show those sites swap between hydroxide and water by rapid proton transfer with extra-framework water.
- Ten-gram grinding makes lanthanum coordination polymers
Manual grinding of LaCl3 with 5-sulfosalicylate and 8-hydroxyquinoline yields ternary CPs whose IR/XPS/MS match a chelated nanocomposite.
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- Squaramide macrocycles that prefer sulfate in water
Meta-linked squaramide macrocycles bind SO42− so tightly in wet DMSO that NMR cannot measure Ka, and they still select sulfate in 50% water.
- Rotating pyrazine rings put a kink in Xe isotherms
SIFSIX-3-Fe takes up more Xe than Kr because its pores match Xe, while an inflection in SIFSIX-3-Ni’s Xe isotherm is attributed to pyrazine rings ordering from disordered to aligned rotations.
- Pyrazine reservoirs that lower cobalt HER overpotential
Moving a redox-active pyrazine on a cobalt polypyridine ligand cuts hydrogen-evolution overpotential by about 200 mV versus pyridine analogues in water.
- Carbon-coated nickel nanoparticles that make CO from CO2
N-doped carbon plus a carbon coat lets metallic Ni nanoparticles reach about 94% CO faradaic efficiency, suppressing hydrogen evolution.
- A MOF that merges Cu and Ru photocatalysis
CR–BPY1 places copper ions next to a Ru-substituted polyoxometalate so N-phenyl-THIQ and ketones couple under an 18 W lamp with pore size-selectivity.
- Stirring time sets GSH-capped silver nanoparticle size
Glutathione reduces AgNO3 at 60 °C; longer stirring grows spherical Ag nanoparticles from about 3 to 6 nm.
- Hard vs soft Ni–Fe catalysts for making hydrogen
A matrix of S-bridged Ni–Fe nitrosyl complexes shows how NO ‘softness’ trades catalytic potential against acid strength and TOF in HER.
- CH···anion bonds that template zinc molecular knots
Weak C–H···anion contacts in water/methanol steer a Zn(II) dynamic library toward a trefoil knot that binds two bromides in its cavity.
- Solid Rh crystals isomerize butene without dissolving
A crystalline Rh σ-alkane complex swaps NBA for alkenes in the solid state and the porous ethene polymorph isomerizes 1-butene with high TOF.
- Gamma-made Ag–Se nanoparticles carrying cefotaxime
Radiolytic Ag, Se, and Ag–Se nanoparticles (about 11–21 nm) are characterized and loaded with cefotaxime for synergistic antimicrobial tests.
- DOS fragments grow hits in several directions at once
A modular diversity-oriented fragment library gave crystallographic hits on several proteins and then short, cheap sequences to many analogues, including a first covalent PBP3 fragment.
- Stibnite in carbon sheets stores sodium better
Natural Sb2S3 anchored on sulfur-doped carbon sheets delivers much higher reversible sodium-storage capacity and cycle retention than raw stibnite.
- Gold dithiolene radical holds a 21 μs spin qubit
Neutral [Au(adt)2] stores the unpaired electron on the ligand, giving phase-memory times up to 21 μs in low-spin solvents and 1.44 μs when doped into a nickel molecular semiconductor.
- Magnetic Cu-on-pumice catalyst for nitro reductions
A cellulose-textured volcanic-pumice magnetite composite bearing copper nanoparticles reduces nitrobenzenes to anilines in eight minutes.
- Glycerol tunes silver nanoparticle size
Silver nitrate reduced in 10–100% glycerol with PVP at room temperature gives plasmonic Ag nanoparticles from ultra-small (~1.8 nm) up to ~160 nm.
- Blackberry-leaf silver nanoparticles against plant pathogens
Rubus fruticosus extract reduces Ag+ to 50–120 nm AgNPs (SPR 449 nm) that fully inhibit two phytopathogens at the highest dose.
- On–off allosteric control of a bifunctional catalyst
A Pt(II) weak-link tweezer and a sulfonate regulator switch a squaramide–amine co-catalyst fully on or off in situ.
- Pyrolysis-free Fe–PIPhen catalyzes alkaline ORR
An Fe2+ coordination polymer of a nitrogen-rich phenanthroline ligand on carbon reduces O2 near 0.85 V with a four-electron pathway.
- Plasmonic SiO2/TiO2 aerogels degrade RhB
Anatase TiO2 grown in silica aerogels, then Ag@Au nanoshells, adsorbs and photocatalyzes rhodamine B far better than TiO2 powder.
- Sputtering Pt onto PEG to make fuel-cell catalysts
Pt sputtered onto liquid PEG, then heat-transferred onto carbon, gives bimodal nanoparticles whose larger population drives ORR activity.
- Isolating rare arylhalodiphosphene P=P–X bonds
A bulky aryl-PPCl diphosphene is isolated as a monomer, swapped to Br and I, and shown to have a P=P double bond unlike diazonium chlorides.
- A new Zn phenanthroline–maleate crystal
Slow evaporation yields [Zn(phen)(maleate)(H2O)]·H2O, a distorted square-pyramidal complex with a 3.45 eV DFT gap and H-bond-dominated packing.
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Questions
What is still open
A powder pattern of a colloid and a single-crystal structure of a molecule are not the same XRD experiment. Fcc Ag peaks at 38.1–77.9° identify a metal phase and roughly a size regime; they do not give a coordination number, a space group of a molecular hydrate, or an E/Z ratio. Quoting 'XRD confirmed the structure' without saying powder versus single-crystal erases that.
XRD can show a lattice that is not the working catalyst. The rhodium hexagonal polymorph's 25% void tracks a 1160 versus 20–29 h⁻¹ TOF split, but post-SC-SC R-factors are already high. On carbon-supported Pt, the particles XRD/TEM size (the 6.7 nm mode) are the ORR-active population, not the leftover 1.8 nm primaries. Structure of what was synthesised is not automatically structure of what turns over.
Ask PaperFren about X-ray Diffraction (XRD)
Study this conceptflashcards and short-answer questions
Blackberry-leaf silver nanoparticles show XRD peaks at 38.1°, 44.4°, 54.5° and 77.9° and TEM diameters of 50–120 nm. What has XRD established, and what has it not?
XRD has established a crystalline fcc-like Ag phase consistent with those angles. It has not given a molecular formula of the leaf-extract cap, a particle-by-particle size histogram (that is TEM), or field efficacy. EDX (~90% Ag) is a composition check, not a purity proof of the organic shell.
Why can the hexagonal rhodium polymorph's 25% void and TOF(90%) = 1160 h⁻¹ not be read as 'XRD measured the catalytic rate'?
XRD (with complementary methods) identifies which crystalline polymorph is porous. The TOF is a separate solid/gas conversion measurement. High post-SC-SC R-factors and still-low industrial TON versus silica-supported systems are reminders that the lattice snapshot is not a process metric.
Heat-treated Pt on carbon is bimodal at 2.5 ± 0.8 nm and 6.7 ± 1.8 nm. If XRD/TEM show both, how do the authors decide which size 'is the catalyst'?
They compare oxygen-reduction activity: the larger 6.7 nm population dominates ORR relative to the smaller 2.5 nm set. Size from diffraction/microscopy is necessary but not sufficient; electrochemical activity assigns which mode matters. No full MEA lifetime is claimed.
Arylhalodiphosphene 8 is 85% E / 15% Z by SC-XRD and shows ³¹P at 433 and 502 ppm with ¹JPP = 574 Hz. What does each method uniquely contribute?
SC-XRD gives the solid-state isomer ratio and E/Z disorder in the lattice. ³¹P NMR identifies the P=P connectivity in the sample that was dissolved or in the bulk molecular solid's spectroscopic fingerprint. Computed 2.96 kcal mol⁻¹ E-over-Z preference is a DFT ranking, not a crystallographic occupancy.