Abstract
Isotropic low thermal expansion (LTE) is highly sought after for practical applications but remains rare due to the strict symmetry constraints that typically restrict its occurrence to cubic systems. In this study, we overcome this limitation in the hexagonal Laves-phase TiFe2 by tailoring the microscopic magnetic structure through vanadium substitution at Fe sites. The resulting Ti(Fe0.85V0.15)2 compound exhibits nearly isotropic LTE within an intrinsically anisotropic hexagonal lattice, with thermal expansion anisotropy reduced by an order of magnitude relative to the parent compound. Comprehensive structural and magnetic characterizations, combined with first-principles calculations, reveal that non-uniform vanadium occupancy creates a heterogeneous local structure that disrupts magnetic frustration. This design triggers significant magnetovolume effects along different crystallographic directions, resulting in the observed near-isotropic LTE. Our work demonstrates that engineering the microscopic magnetic structure is a viable strategy for achieving isotropic physical properties in magnetic functional materials beyond cubic systems.
| Original language | English |
|---|---|
| Article number | 103190 |
| Journal | Materials Today |
| DOIs | |
| State | Accepted/In press - 2026 |
Funding
This work was supported by the Beijing Outstanding Young Scientist Program ( JWZQ20240101015 ), the National Natural Science Foundation of China ( 22522103 and 12574007 ), and the Fundamental Research Funds for the Central Universities ( FRF-EF-25-07A ). The SXRD experiments were performed at SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (2024A1691). A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the ORNL. The beam time was allocated to (NOMAD) on proposal number IPTS-33670.1. We acknowledge Dr. Chin-Wei Wang for collecting the NPD data at the high-intensity diffractometer Wombat of the ANSTO. We acknowledge the Space Environment Simulation Research Infrastructure for its help in our experiment.