Synthesis and Structural Characterization of Sb-Doped TiFe2Sn Heusler Compounds

Abstract

Heusler compounds form a numerous class of intermetallics, which include two families with general compositions ABC and AB 2 C, usually referred to as half-and full-Heusler compounds, respectively. Given their tunable electronic properties, made possible by adjusting the chemical composition, these materials are currently considered for the possible use in sustainable technologies such as solar energy and thermoelectric conversion. According to theoretical predictions, Sb substitution in the TiFe 2 Sn full-Heusler compound is thought to yield band structure modifications that should enhance the thermoelectric power factor. In this work we tested the phase stability and the structural and microstructural properties of such heavily-doped compounds. We synthesized polycrystalline TiFe 2 Sn 1-x Sb x samples, with x = 0, 0.1, 0.2 and 1.0 by arc melting, followed by an annealing treatment. The structural characterization, performed by x-ray powder diffraction and microscopy analyses, confirmed the formation of the Heusler AB 2 C structure (cF16, Fm-3m, prototype: MnCu 2 Al) in all samples, with only few percent amounts of secondary phases and only slight deviations from nominal stoichiometry. With increasing Sb substitution we found a steady decrease of the lattice parameter, confirming that the replacement takes place at the Sn site. Quite unusually, the as cast samples exhibited a higher lattice contraction than the annealed ones. The fully substituted x=1.0 compound, again adopting the MnCu 2 Al structure, does not form as stoichiometric phase and turned out to be strongly Fe deficient. The physical behavior at room temperature indicated that annealing with increasing temperature is beneficial for electrical and thermoelectrical transport. Moreover, we measured a slight improvement of electrical and thermoelectrical properties in the x=0.1 sample and a suppression in the x=0.2 sample, as compared to the undoped x=0 sample.

Roadmap on thermoelectricity

“…Nevertheless, the optimization of these materials is largely attempted in many laboratories. The insertion of different lanthanide ions in Co/Ni- [85], Fe/Ni- [86] and Fe/ Co- [87] based skutterudites, as well as the partial substitution of Sb by an aliovalent ion [87,88], can be considered in this perspective; the partial substitution of Sn by Sb in the Heusler phase Fe 2 TiSn pursues the same goals [89,90].…”

First-Principles Calculations to Investigate the Stability and Thermodynamic Properties of a Newly Exposed Lithium–Gallium–Iridium-Based Full-Heusler Compound

“…Several researchers from all over the world have focused on Heusler metals because of their tunable properties, including their high Curie temp, tunable electronics structure, acceptable semiconducting lattice parameter, and varied magnetic property. − Heusler alloy intermetallic compounds are attractive options for thermoelectric materials − and topological insulators. , They can also be used as shape-memory materials, spin-gapless semiconductors, and other forms of thermoelectric materials. − Heusler substances can be broadly categorized into half-Heusler, full-Heusler, and last, quaternary-Heusler. These structures’ stoichiometric configurations are XYZ, XY 2 Z, and XYMZ, in which X, Y, and M are typically transition metals and Z is the leading group component. − XY 2 Z, a full-Heusler configuration, settles in a cubic L2 1 arrangement (MnCu 2 Al-sample) with the spatial group Fm 3̅ m (# 225). ,, In this article, we will investigate the physical characteristics of one such type. LiGa 2 Ir Heusler is a relatively new intermetallic compound that has attracted attention in the scientific community due to its unique combination of physical and superconducting properties .…”

“… 18 − 20 XY 2 Z, a full-Heusler configuration, settles in a cubic L2 1 arrangement (MnCu 2 Al-sample) with the spatial group Fm 3̅ m (# 225). 18 , 21 , 22 In this article, we will investigate the physical characteristics of one such type. LiGa 2 Ir Heusler is a relatively new intermetallic compound that has attracted attention in the scientific community due to its unique combination of physical and superconducting properties.…”