Fersi & Dalia (Bull. Mater. Sci. 2026) synthesized Zr3TiFe8 for the first time; the refined R3m structure matches the measured-data-call candidate CIF to 0.25%. Measured Tc and Ms are still absent, so the 450-500 K gate remains untested.
In April 2026, R. Fersi and A. P. Dalia published the first synthesis of Zr3TiFe8 (Bulletin of Materials Science 49, 65, DOI 10.1007/s12034-026-03588-6). Rietveld refinement of room-temperature XRD gives a trigonal R3m structure with a = 4.952 Å and c = 24.215 Å. That matters here for a simple reason: Zr3TiFe8 is rank 9 on the RE-free PM lab shortlist and one of the nine candidates in our measured-data call, and until now nothing about the phase was established experimentally.
The candidate CIF on the call is a Materials Project structure relaxed with Orb v3, which preserved R3m throughout (R3m → R3m). Converted to the hexagonal setting it gives a = 4.9396 Å, c = 24.1818 Å. Against the refinement:
a (Å) | c (Å) | |
|---|---|---|
Fersi & Dalia 2026 (XRD, refined) | 4.952 | 24.215 |
Our candidate (MP + Orb v3, relaxed) | 4.9396 | 24.1818 |
difference |
Two independent routes, a computed database entry relaxed with a machine-learned potential and a laboratory XRD refinement, landed on the same structure within a quarter of a percent. The candidate is real, and it is arc-meltable.
Measured: the structure, at room temperature.
Not measured: Curie temperature, saturation magnetization, magnetic ordering. The paper's own DFT (GGA-PBE on the refined structure) finds Fe moments of 2.10-2.28 μB and a ferromagnetic ground state, with no imaginary phonons across all 36 modes; the authors argue from Fe8-sublattice optical modes at 10-14 THz that spin-phonon coupling is notable and hypothesize a high Curie temperature. A hypothesis is what our model Tc of 473 K is too. The two computed pictures are consistent with each other, but neither is a measurement.
The blind spot is narrower than it was a week ago: the phase exists, is synthetically accessible, and is structurally pinned. What remains is exactly what the call requested for this candidate: one thermomagnetic M(T) scan across 300-600 K and one room-temperature M(H) to 5 T. A single Tc number decides whether this top-10 candidate passes or fails the 450-500 K operating-margin gate.
The slice row
−0.14% |