Abstract
Fe-doped MnNiGe alloys were successfully synthesized by solid-state reaction. Giant negative thermal expansion (NTE) behaviors with the coefficients of thermal expansion (CTE) of −285.23 × 10−6 K−1 (192–305 K) and −1167.09 × 10−6 K−1 (246–305 K) have been obtained in Mn0.90Fe0.10NiGe and MnNi0.90Fe0.10Ge, respectively. Furthermore, these materials were combined with Cu in order to control the NTE properties. The results indicate that the absolute value of CTE gradually decreases with increasing Cu contents. In Mn0.92Fe0.08NiGe/x%Cu, the CTE gradually changes from −64.92 × 10−6 K−1 (125–274 K) to −4.73 × 10−6 K−1 (173–229 K) with increasing value of x from 15 to 70. The magnetic measurements reveal that the NTE behaviors in this work are strongly correlated with the process of the magnetic phase transition and the introduction of Fe atoms could also change the spiral anti-ferromagnetic (s-AFM) state into ferromagnetic (FM) state at low temperature. Our study launches a new candidate for controlling thermal expansion properties of metal matrix materials which could have potential application in variable temperature environment.
Highlights
Solid materials usually expand during heating while contract during cooling, i.e., positive thermal expansion (PTE)
The room temperature X-ray diffraction (XRD) patterns of MF8, MF10, MF16, and NF10 are collected to inspect the effect of Fe doping on the crystal structure of MnNiGe alloy
It is clear that the large temperature windows of observed negative thermal expansion (NTE) behaviors are in consistent with the magnetization decreasing slowly during the AFM-PM transformation in MF10 and NF10, which indicates a strong relationship between magnetism and thermal expansion properties in these serials compounds, as well the composites
Summary
Solid materials usually expand during heating while contract during cooling, i.e., positive thermal expansion (PTE). We prepared Fe-doped MnNiGe compounds successfully by solid-state reaction, and observed the giant NTE properties near room temperature (RT) in pure parent alloys.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have