Journal Article

PUBDB-2025-05469

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Local chemical disorder as the origin of anomalous thermal expansion in $TiFe_2$ Laves phase alloys

Azavedo, M.Extern* ; Dias, E. T.Extern* ; Srihari, V. ; Dankelman, R. ; Dhiman, I. ; Priolkar, K. (Corresponding author)Extern*

2025
RSC Publ. Cambridge

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Please use a persistent id in citations: doi:10.1039/D5CP03136B

Abstract: TiFe2 alloys, a C14 Laves phase system, exhibit negative or zero thermal expansion (NTE/ZTE) despite theabsence of the first-order transitions that typically drive such behavior in related compounds. Across thecompositional range, the magnetic ground state evolves from ferromagnetic ordering in Fe-rich alloysto antiferromagnetic ordering in Ti-rich variants, yet the thermal expansion response remains invariant.High-resolution synchrotron X-ray and neutron diffraction detect no anomalies in lattice volume ormagnetic moment, and Rietveld refinements exclude significant antisite disorder. In contrast, Fe and TiK-edge extended X-ray absorption fine structure (EXAFS) and elemental mapping via energy-dispersiveX-ray spectroscopy (EDAX) reveal pronounced nanoscale compositional inhomogeneity, forming Fe-richand Ti-rich regions. The coexistence of competing ferro- and antiferromagnetic interactions from thesechemically distinct domains gives rise to an invar-like effect below a characteristic temperature, T*.These results establish local chemical disorder as a key mechanism for stabilizing NTE/ZTE behavior inintermetallic systems, independent of long-range structural or magnetic transitions.

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Contributing Institute(s):

1. FS DOOR-User (FS DOOR-User)

Research Program(s):

1. FS-Proposal: I-20210145 (I-20210145) (I-20210145)
2. INDIA-DESY - INDIA-DESY Collaboration (2020_Join2-INDIA-DESY) (2020_Join2-INDIA-DESY)
3. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)

Experiment(s):

1. PETRA Beamline P65 (PETRA III)

Appears in the scientific report 2025

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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