Samples and preparation
What a beam-time sample of these garnets must be, and what has to happen at home before February 2027 (P0). The rule is simple: every number refined at the facility will be compared with a number measured at home on the same powder.
Which samples
- K12 fresh: the twelve compositions of the key set re-made by the thesis's M-SSR route, in one campaign, with the precursors' lots recorded. Powders of at least 3 g each (2–3 g fill an 8 mm vanadium can for D2B; 0.1 g is enough for capillaries and XAS), and sintered pellets made exactly as in the thesis (1200 °C, 6 h, mother powder, covered alumina boats) for the crushed-pellet measurements.
- A38 as stored: the thesis's 38 powders as they are, for the synchrotron survey (P2) and the room-temperature neutron survey (P3), with their storage history written down.
- Twins: one fresh powder of Ga–Ta and of Ga–Y₀.₂₀–Ta kept under argon, and its twin left in air for a known time: the protonation measured, not guessed (G08).
- A zirconia-crucible pair: Ga–Y₀.₂₀–Ta sintered in an alumina boat and in a zirconia or MgO crucible, to separate the effect of Al (G03).
- References for EXAFS: \(\mathrm{Y_{2}O_{3}}\), an yttria-stabilised zirconia (Y on a Zr-like site), \(\mathrm{Y_{3}Al_{5}O_{12}}\) (Y in 8-fold coordination), \(\mathrm{Ga_{2}O_{3}}\), \(\mathrm{LiGaO_{2}}\), \(\mathrm{Sc_{2}O_{3}}\), a Rb salt.
Measured at home, on the same powders
| ICP-OES: Li, Ga, Al, La, Zr, M (and Ta or Sc) |
the composition every occupancy is refined under; Li loss; Al uptake; the Zr/La ratio of the \(\mathrm{Li_{2}ZrO_{3}}\) question |
P1–P4, G02, G03, G09 |
| TGA–MS (\(\mathrm{H_{2}O}\), \(\mathrm{CO_{2}}\)) to 900 °C |
protons and carbonate |
G08, P1 |
| Laboratory XRD with an internal Si standard |
lattice parameters with esd and zero shift stated; phase check before shipping |
all |
| Archimedes density with the theoretical density from the refined cell and composition |
a density the conductivity can be compared with |
G09 |
| Impedance at higher frequency (MHz) or low temperature on the best compositions |
bulk and grain boundary separated, the activation energy of the lattice |
G10 |
Handling
- From the last calcination to the beam: argon glove box, sealed vials, vanadium cans and capillaries loaded under argon (the facilities have glove boxes), time in air recorded.
- Shipping to Grenoble in sealed containers; the facilities' sample declaration (chemical safety) done with the proposal.
- ⁷Li: natural lithium for the first round; ⁷\(\mathrm{Li_{2}CO_{3}}\) for two compositions only if D2B shows the lithium occupancies limited by absorption (a supplier quote first).