Mn-for-Fe substitution in Fe1-xMnxIn2S4 thiospinel – Crystal structure and thermoelectric properties. (May 2021)

• Record Type: Journal Article
• Authors: Wyżga, Paweł; Veremchuk, Igor; Koželj, Primož; Leithe-Jasper, Andreas; Gumeniuk, Roman
• Is Part Of: Journal of physics and chemistry of solids. Volume 152(2021)
• Publication Date: 2021-05
• Subjects: Solid solution -- Thermoelectric properties -- Indium thiospinel -- Chemical substitution; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2021.109984
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: Crystal structure as well as magnetic and thermoelectric properties of the quaternary Fe1- x Mn x In2 S4 thiospinel were investigated. A complete homogeneity range between FeIn2 S4 and MnIn2 S4 was confirmed by powder X-ray diffraction phase analysis supported by a linear increase of the cubic unit-cell parameter for greater Mn content, obeying Vegard's law. Rietveld refinement revealed a gradual decrease of the inversion parameter i upon incorporation of Mn into the structure, which indicated a change from inverse spinel (for FeIn2 S4 ) to nearly-normal spinel (for MnIn2 S4 ). This quaternary compound is an n -type semiconductor with high electrical resistivity ρ > 5 × 10 −4 Ω m and Seebeck coefficient | α | > 250 μV K −1 above RT. The thermal conductivity followed a compositional dependence typical for solid solutions and thus revealed a minimum for samples with 0.4 < x ≤ 0.8. The power factor and thermoelectric figure of merit monotonously decreased for greater Mn content within the quaternary compound. All samples showed magnetic transitions below 12 K with antiferromagnetic interactions. The determined effective magnetic moments corresponded to values for Fe 2+ and Mn 2+ ions. Graphical abstract: Image 1 Highlights: Quaternary Fe1- x Mn x In2 S4 thiospinels ( x = 0.2, 0.4, 0.6, 0.8, 1) were synthesized. A continuous homogeneity range between FeIn2 S4 and MnIn2 S4 was confirmed. Spinel crystal structure changed from inverse to nearly-normal upon increasing x. High electrical resistivity limited the power factor PF < 1.7 × 10 −4 W m −1 K −1 . Thermal conductivity revealed a trend typical for solid solutions.