ICP-OES; TGA–MS; laboratory XRD with an internal standard; glove box; EIS to higher frequency or lower temperature

No proposal: the groups' own means, from November 2026

K12 re-synthesised fresh by the thesis's M-SSR route, as powders (\(\ge 3\) g each) and sintered pellets; the stored powders of the thesis kept for comparison.

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• Li, Ga, Al, La, Zr and M by ICP-OES on powders and pellets: the constraint every Li occupancy is refined under.
• TGA–MS (\(\mathrm{H_{2}O}\), \(\mathrm{CO_{2}}\)) on the same powders: protonation and carbonate.
• Laboratory XRD with Si (NIST 640) as internal standard: lattice parameters with esd and zero shift stated, before and after storage.
• Storage under argon from synthesis to beam; a deliberately aged twin of Ga–Ta and Ga–Y₀.₂₀–Ta.
• The decision on ⁷Li: natural Li for the matrix; ⁷\(\mathrm{Li_{2}CO_{3}}\) for two or three compositions if the D2B data ask for it.

Samples whose composition is known and whose history is recorded; the preliminary data every proposal needs.

Panels fund questions, not samples. The ICP and TGA numbers turn "we want to see the Li" into "the nominal Li is 6.5, ICP gives x, neutrons will say where it is".

Re-synthesis may not reproduce the thesis's phase fractions exactly; that is itself a result (reproducibility), and the stored powders measured beside the fresh ones say how much.

Before mid-February 2027

D2B (λ = 1.594 Å, Δd/d \(\approx\) \(5\times10^{-4}\), 2\(\theta\) to 160°); alternative D20 in its high-resolution Ge configuration

ILL standard proposal, College 5 (materials), with UPV/EHU proposers ensuring the two-thirds member-country rule; cross-referenced to P2

K12 (fresh, from P0), 2–3 g each, natural Li, in 8 mm vanadium cans; two sintered pellets crushed (Ga–Y₀.₂₀–Ta, Ga–Rb₀.₀₃–Sc).

\(\approx 8\) shifts (2.7 days): about 4 h per sample for 14 samples, plus empty can, vanadium and Si standard. Estimate.

• Full patterns to \(d \approx 0.81\) Å at room temperature.
• Joint Rietveld refinement with the ID22 pattern of the same powder (P2) in diff-ref-struct: lattice and profile from X-rays, Li/Ga/Al occupancies, O1/O2 coordinates and displacement parameters from neutrons.
• Constraints: ICP composition (P0), charge balance, site capacities.

For each composition: Li over 12a, 12b and 48e with esd (the measured vacancy concentration); Ga on 12a; Al or its upper bound; the acentric O distortion; Ba on the La site for the Ba series; H from the background. The vacancy argument of the thesis tested against measured Li contents.

Lithium and oxygen carry 57 % of the neutron scattering power of the garnet against 6 % in X-rays; every Li question is 2–4 times more visible (Contrast page). D2B's resolution separates the cubic and tetragonal garnets and \(\mathrm{Li_{2}ZrO_{3}}\).

Absorption of natural Li (\(\mu \approx 1.5\) \(\mathrm{cm}^{-1}\), \(\mu R \approx 0.37\) in an 8 mm can): correctable, but ⁷Li (μ \(\approx 0.12\) \(\mathrm{cm}^{-1}\)) would remove it for the two compositions where the Li occupancy matters most.

15 February 2027 (ILL standard round)

ID22 (31–35 keV, 13-channel analyser, FWHM \(\approx 0.0025\)°, robot for 75 capillaries); alternative BM25 SpLine through the Spanish CRG route

ESRF standard proposal, UPV/EHU as main proposer; or a BAG with UPV/EHU as PI and at least three groups

A38 calcined powders and K12 crushed pellets, 0.5 mm capillaries, with an internal standard for the amorphous fraction; \(\mathrm{LaB_{6}}\) / Si for calibration.

\(\approx 6\) shifts: 50 patterns of a few tens of minutes with the robot, plus resonant data at the Y K edge (17.04 keV) for 3 compositions at 3 energies. Estimate.

• Lattice parameters with esd for all 38 under one protocol (the two chapters on one footing).
• Phase fractions (c-LLZO, t-LLZO, \(\mathrm{Li_{2}ZrO_{3}}\), \(\mathrm{BaZrO_{3}}\), \(\mathrm{Sc_{2}O_{3}}\), \(\mathrm{Y_{2}O_{3}}\), \(\mathrm{La_{2}Zr_{2}O_{7}}\)) with detection limits \(\approx 0.1\) wt%, for powders and pellets.
• La-site occupancy (Y, Rb on La) under the ICP constraint; weak \(I\bar{4}3d\) reflections; peak shapes (strain, compositional spread).
• Resonant diffraction below and at the Y K edge: the Y contrast changed on purpose, site by site.

The structural table of the thesis remade with esd; a closed mass balance for each composition; the powder-to-pellet change of the phase state; the fraction of Y missing from the La site.

Resolution and statistics no laboratory instrument reaches; the X-ray contrast is the right one for Y, Rb, Ta and Sc on their sites (Contrast page).

Rb, Ba and La absorb at 31–35 keV in 0.5 mm capillaries; diluted or thinner capillaries, or 60 keV, if needed.

1 March 2027 (ESRF standard round)

D20 (1.30 Å, \(\approx\) \(10^{8}\) n \(\mathrm{cm}^{-2}\) \(\mathrm{s}^{-1}\); furnace to 1100 °C); alternatives through the Spanish CRG routes: D1B (CNRS–CSIC) and XtremeD (INMA–CSIC), both with furnaces to 1200 K

ILL standard proposal; or the D1B / XtremeD CRG calls (Spanish share)

A38 at room temperature (the compositions not in P1 for Li trends across the matrix); four compositions heated to 1000 K: Ga–Ta, Ga–Y₀.₂₀–Ta, Ga–Rb₀.₀₃–Sc, Ga–Rb₀.₂₀–Ta (tetragonal–cubic transition).

\(\approx 6\) shifts: about 15 min per room-temperature pattern, 6–8 h per heating ramp. Estimate.

• Room temperature: Li content and tetragonal fraction across the 38, at lower resolution than D2B but with the same contrast.
• Ramps to 1000 K: lattice expansion, the tetragonal–cubic transition, Li loss in situ, high-temperature datasets for nuclear density maps of the Li pathways.

The Li-content trend of every series; the tetragonal–cubic transition temperature against the measured Li content; Li density maps at 300, 600 and 900 K for the four compositions.

D20's flux makes the whole matrix and the ramps possible in days. The Spanish CRG instruments give a second route if the ILL round is tight.

Li volatilisation above 900 °C in the furnace: closed Nb or Pt containers, and the ramp stopped below the sintering temperature.

15 February 2027 (ILL); spring CRG calls (D1B, XtremeD)

BM23 (4.5–90 keV, multi-sample holders); BM08 LISA or BM20 for the Sc K edge (4.49 keV); BM25 SpLine (Spanish route) for edges above 5 keV

ESRF standard proposal; BM25 through the Spanish CRG committee (March and September calls)

Ga–Y–Ta (x = 0.05, 0.10, 0.20, 0.30), Ga–Y–Sc (0.05, 0.20), Ga–Rb–Ta (0.20), Ga–Rb–Sc (0.03, 0.20), the two references; references \(\mathrm{Y_{2}O_{3}}\), YSZ, \(\mathrm{Y_{3}Al_{5}O_{12}}\), \(\mathrm{RbNO_{3}}\) or \(\mathrm{Rb_{2}CO_{3}}\), \(\mathrm{Ga_{2}O_{3}}\), \(\mathrm{LiGaO_{2}}\), \(\mathrm{Sc_{2}O_{3}}\). Pellets diluted in cellulose or BN, transmission.

\(\approx 9\) shifts: Y K (17.04 keV) about 10 samples, Rb K (15.20 keV) 4, Ga K (10.37 keV) 6, Zr K (18.0 keV) 4, with references. Sc K separately on BM08 or BM20. Estimate.

• Y K EXAFS: Y–O coordination number and distance, Y–cation shells: 6-coordinated Zr site against 8-coordinated La site.
• Rb K: the Rb environment in the garnet against Rb-rich second phases.
• Ga K: tetrahedral Ga, Ga–O distance, the local picture behind the 12a occupancy of P1.
• Zr K: the octahedral site as seen from Zr, for the Y and Sc series.

The Y site fractions of G04 measured locally; Rb and Ga environments confirmed; the Sc site.

Only a local, element-specific probe can tell Y on the Zr site from Y on the La site; neither diffraction probe can (Contrast page, cases y-zr and y-la).

Ba L3 is cut by the La L3 edge 236 eV above it and Ta L3 by Ga K: Ba and Ta only by K-edge (37.4 and 67.4 keV) if needed, or not at all in the first round.

1 March 2027 (ESRF); March call (BM25)

ID15A (X-ray PDF; oven to 1200 K), ILL D4c (neutron PDF); BM31 (XAS + XRD + PDF in situ) or ID15A for the synthesis

After P1–P4 results; September 2027 rounds

Ga–Ta, Ga–Y₀.₂₀–Ta, Ga–Rb₀.₀₃–Sc for PDF; the precursor mixture of Ga–Y₀.₂₀–Ta for the synthesis in situ (\(450 \to 900\) °C).

\(\approx 3\) shifts ID15A, \(\approx 2\) days D4c. Estimate.

• X-ray and neutron PDF: local distortions around Y, Rb, Ga; Li–O and Li–Li correlations.
• In situ synthesis: the order in which \(\mathrm{La_{2}Zr_{2}O_{7}}\), \(\mathrm{Li_{2}ZrO_{3}}\), t- and c-LLZO form along the thesis's M-SSR route, and where lithium is lost.

The local structure behind the average one; the step of the synthesis where the \(\mathrm{Li_{2}ZrO_{3}}\) of G09 forms.

It answers what P1–P4 leave open, and connects the thesis's synthesis chapter (Chapter II) to the structures.

Only worth asking once P1–P2 have shown which compositions carry the effects.

September 2027 rounds