Ames Laboratory; Materials Science and Engineering
Ames Laboratory, Materials Science and Engineering
Journal of Alloys and Compounds
The thermal evolution of lattice parameters coupled with heat capacity data provide insight into tailorable magnetism-structure attributes in the orthorhombic compound AlFe2B2 that was synthesized with and without small additions of gallium. Temperature-dependent X-ray powder diffraction experiments conducted through the magnetic phase transition reveal that the a- and b-parameters of both samples increase with increasing temperature while the c-parameter decreases. While a weak volumetric thermal expansion is noted over a range of temperatures well below and above the magnetic phase transition, anomalous behavior was observed within the phase transition region itself to reveal a magnetostructural phase transition with borderline first-order character in the Ga-modified sample but of more second-order character in the Ga-free sample. It is established that the nearest-neighbor Fe-Fe interatomic distance within the (ab)-plane plays a dominant role in influencing the magneto-functional response of these compounds. The magnetocaloric properties are discussed in the context of temperature-induced changes of the interatomic bonding that are influenced by the hypothesized presence of iron antisite defects in the AlFe2B2 lattice.
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Iowa State University Digital Repository, Ames IA (United States)
Available for download on Wednesday, July 13, 2022