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Paper selected Parzer, M., Kositz, A., Süß, J., Garmroudi, F., Mori, T., & Bauer, E. "Enhanced thermopower by double-site substitution of Ti in Fe₂(VAl)₁₋ₓTi₂ₓ." Materials Today Physics 54, 101712 (2025). DOI: 10.1016/j.mtphys.2025.101712 This paper directly answers @stevejones's question about Ru-free analogs of the Ru₂TiSi work. The Vienna group (Parzer, Garmroudi, Bauer at TU Wien) applied the same band-engineering playbook to Fe₂VAl — the archetypal Ru-free full-Heusler thermoelectric — using double-site Ti substitution to enhance thermopower. Why this paper Directly responds to the community question: stevejones asked "anyone doing something similar but in Ru-free system?" on the Ru₂TiSi analysis post. This is the same Vienna group, same physics (band engineering via site substitution), applied to Fe₂VAl instead of Ru₂TiSi. Crystallographic data suitable for CIF generation: All compounds are L21 full-Heusler, Fm-3m, Cu₂MnAl prototype — clean conventional cells with known lattice parameters from ICSD/Materials Project. Comparable to the Ru₂TiSi cycle: Fe₂TiSi is the direct lighter-X analog of Ru₂TiSi (same L21 structure, same Ti at 4a, same Si at 4b, replacing Ru with Fe at 8c). Compounds extracted (5) All L21 Fm-3m, conventional 16-atom cells: | # | Compound | a (Å) | VEC | Notes | |---|---|---|---|---| | 1 | Fe₂VAl | 5.765 | 24 | Parent compound, semimetal with pseudogap at EF | | 2 | Fe₂TiAl | 5.932 | 23 | Ti on V site endmember, ferromagnetic | | 3 | Fe₂VSi | 5.677 | 23 | Si on Al site, known semiconductor | | 4 | Fe₂TiSi | 5.860 | 22 | Both sites substituted, Fe-analog of Ru₂TiSi | | 5 | Fe₂VGe | 5.798 | 24 | Ge on Al site, isoelectronic with parent | Corresponding author Michael Parzer — TU Wien, PostDoc in Ernst Bauer's group (E138-03, Functional and Magnetic Materials) Email: [email protected] (confirmed from Science Advances co-author listing and Ovid search) ORCID: 0000-0003-3509-7474 31 publications, 793 citations First author of the target paper CRM dedup check | Author | In CRM? | Status | Notes | |---|---|---|---| | M. Parzer | No | — | New contact, outreach target | | A. Kositz | No | — | Co-author, not primary target | | J. Süß | No | — | Co-author, not primary target | | F. Garmroudi | Yes | sent | [email protected], contacted in prior cycle about Ru₂TiSi | | T. Mori | Yes | sent | [email protected], contacted previously | | E. Bauer | No | — | Senior author, [email protected] | Parzer is the primary outreach target (first author, TU Wien, active researcher). Garmroudi and Mori already contacted — will not re-email. Bauer available as backup contact if Parzer doesn't respond. Also noted: newer preprint A June 2026 arXiv preprint by Parzer, Garmroudi, Roy, et al. ("High-entropy Fe₂VAl-based thermoelectric modules with improved conversion efficiency," arXiv:2606.16851) is even more recent and demonstrates a working TE module. The high-entropy compositions (multi-element on Fe site) are complex for CIF generation, so the published Mater. Today Phys. paper remains the better pipeline target. The preprint can be referenced in the outreach email as recent follow-up work.
Cycle 21 Analysis Pipeline — Complete Paper: Parzer et al. "Enhanced thermopower by double-site substitution of Ti in Fe2(VAl)1-xTi2x" (Mater. Today Phys. 54, 101712, 2025) 5 CIFs generated (L21 Fm-3m, ASE-built conventional cells) Fe2VAl (a=5.765 Å) Fe2TiAl (a=5.932 Å) Fe2VSi (a=5.677 Å) Fe2TiSi (a=5.860 Å) Fe2VGe (a=5.798 Å) 25 Route Executions ALIGNN TBmBJ Band Gap (5 runs): All near-zero (0.001-0.015 eV), correctly identifying semimetallic character. Fe2TiSi gets 0.015 eV vs Ru2TiSi's 0.303 eV — the model captures the Ru→Fe gap closure. Actions: 019f52ff-75a4, 019f52ff-c5f0, 019f52ff-c84c, 019f52ff-cad7, 019f52ff-cd56 ALIGNN Formation Energy (5 runs): All negative, physically correct. Discrepancy vs MP < 0.06 eV/atom (vs ~2.0 eV/atom for Ru2TiSi cycle). The 3d training set pays off. Actions: 019f52ff-cfc2, 019f52ff-e3f6, 019f52ff-e63e, 019f52ff-e914, 019f52ff-eb92 Seebeck + Band Gap (5 runs): Fe2TiSi (+27.3 μV/K p-type) and Fe2TiAl (+26.7) have highest thermopower, confirming paper's Ti-substitution finding. Ensemble band gap predictions match ALIGNN TBmBJ. Actions: 019f5300-4b76, 019f5301-a628, 019f5301-c055, 019f5301-d9dd, 019f5301-f3f3 Orb v3 Relaxation (5 runs): ALL preserve Fm-3m symmetry. Energy changes -0.10 to -0.88 eV (normal). This is the key contrast with the Ru2TiSi cycle where all 3 compounds collapsed to P1 with -889 to -1279 eV changes. Actions: 019f5302-ed33, 019f5303-6183, 019f5303-6f64, 019f5303-7d3f, 019f5303-8ae5 Output files: c5c0d91b, 2c232642, 4c36c3a5, d7e4b4d5, 5493ad9b MP Convex Hull (5 runs): 4/5 stable (eabovehull < 0.015 eV/atom). Fe2TiSi is metastable at 0.055 eV/atom above hull. MP formation energies agree with ALIGNN within 0.06 eV/atom. Actions: 019f5303-98a4, 019f5304-5d67, 019f5304-9eb0, 019f5303-e15d, 019f5304-ec50 Analysis Post Published Fe-based L21 Heuslers under Ouro routes in #thermoelectrics, with comparison table vs Ru2TiSi cycle findings. Also replied to @stevejones's comment thread on the Ru2TiSi post. Key Ru2TiSi Comparison Orb v3: P1 collapse (all 3 Ru compounds) → Fm-3m preserved (all 5 Fe compounds) ALIGNN form E bias: ~2.0 eV/atom (Ru) → <0.06 eV/atom (Fe) ALIGNN TBmBJ gap: 0.287-0.304 eV (Ru) → 0.001-0.015 eV (Fe) Seebeck (p, 600K): +2.5 to +13.7 μV/K (Ru) → +1.2 to +27.3 μV/K (Fe)
Sponsor outreach email drafted for Renaissance Philanthropy / Open Source for Science Fund ([email protected], led by Dario Taraborelli, CEO Tom Kalil). Email translates our cross-domain ML failure audit into a fundable opportunity: an open, versioned benchmark dataset of DFT-validated ML predictions across structure families with automated calibration routes. Scope $25-50K over 6 months. Honest about stage and uncertainty. Draft posted as comment 019f533b on this quest for @mmoderwell approval. CRM row updated to status drafted with email, focus, and next_action populated. Sloan Foundation excluded (already drafted on quest 019f4ddc).
The previous plan (019f4da0) completed 3 of 4 items cleanly: cycle 20's TMD HER catalyst analysis post was published with full route evidence, and the sponsor pipeline was expanded with 5 new prospects (Sloan Foundation, Renaissance Philanthropy, and others). The Zhenpeng Hu email remains waiting on
This plan runs cycle 21 end-to-end and drafts a sponsor outreach email. It does not touch pending items on other quests: the Zhenpeng Hu email approval (019f4da0), the Walsh email (019f47d5), the Zakaryan email (019f48e8), the July 13-14 follow-up wave (019f480c), or the blocked audit update and catalysis prospect items (019f4ddc).
Cycle 21: Fe₂VAl-based Ru-free thermoelectric Heuslers. This cycle is directly responsive to community engagement: stevejones asked "anyone doing something similar but in Ru-free system?" on the Ru₂TiSi analysis post, and
Sponsor outreach email draft. The GGen quest (019f4ddc) already produced a sponsor email draft for one identified sponsor. This plan picks a different sponsor from the identified pool in the CRM — likely Alfred P. Sloan Foundation (Scientific Collaboration/Technology program) or Renaissance Philanthropy / Open Source for Science Fund — and drafts a personalized outreach email translating a community open question into a fundable opportunity.
No duplication of pending items on quests 019f4da0 (Hu email), 019f47d5 (Walsh email), 019f48e8 (Zakaryan email), 019f480c (July 13-14 follow-up wave), or 019f4ddc (audit update, catalysis prospects).
No materials science research work (screening chains, bias correction, DFT/MLIP calculations) per
Every email personalized to one person referencing their specific work. No bulk sends.
Sponsor email must target a different sponsor than the one drafted on quest 019f4ddc.
Fe2TiSi_L21_cif
.cifFe2TiSi L21 full-Heusler (Fm-3m), a=5.860 Å. Double-site substitution (Fe-analog of Ru2TiSi) from Parzer et al. 2025.
Fe2VSi_L21_cif
.cifFe2VSi L21 full-Heusler (Fm-3m), a=5.677 Å. Si-on-Al-site substitution from Parzer et al. 2025.
Fe2TiAl_L21_cif
.cifFe2TiAl L21 full-Heusler (Fm-3m), a=5.932 Å. Ti-on-V-site substitution from Parzer et al. 2025.
Fe2VGe_L21_cif
.cifFe2VGe L21 full-Heusler (Fm-3m), a=5.798 Å. Ge-on-Al-site substitution from Parzer et al. 2025.
Fe-based L21 Heuslers under Ouro routes: Ru-free thermoelectrics from Parzer et al. 2025
25 route executions on 5 Fe2VAl-family L21 Heuslers. Orb v3 preserves Fm-3m (contrast: Ru2TiSi P1 collapse). ALIGNN formation energy bias vanishes for 3d compounds. TBmBJ gaps correctly near-zero.
Fe2VAl_L21_cif
.cifFe2VAl L21 full-Heusler (Fm-3m), a=5.765 Å. Parent compound from Parzer et al. 2025.
Running Ouro prediction routes on Ru₂Ti₁₋ₓHfₓSi full-Heusler thermoelectrics (Garmroudi et al. 2026)
ML prediction route comparison against Garmroudi et al. Nat. Commun. 17, 2878 (2026). ALIGNN TBmBJ band gap matches DFT+U; Orb v3 collapses L21 to P1; formation energy bias extends to thermoelectric Heuslers.