(Cu)tet(Cr2–xSnx)octS4–ySey Spinels: Crystal structure, density functional theory calculations, and magnetic behavior
Autor
Moris-López, Silvana
Valencia-Gálvez, P.
Mejía-López, José
Peña, Octavio
Barahona-Huenchumil, Patricia
Galdámez, Antonio
Fecha
2019Resumen
A new series of (Cu)tet[Cr2–xSnx]octS4–ySey compounds was prepared by solid-state reaction at high temperature. Determination of the crystal structures by single-crystal X-ray diffraction revealed that CuCr1.0Sn1.0S2.1Se1.9, CuCr1.2Sn0.8S2.1Se1.9, CuCr1.3Sn0.7S2.2Se1.8, and CuCr1.5Sn0.5S2.2Se1.8 crystallize in a normal spinel-type structure (cubic Fd3m space group). The powder X-ray diffraction patterns and Rietveld refinements of nominal CuCr2–xSnxS2Se2 (x = 0.2, 0.4, 0.6, 0.8, and 1.0) were consistent with single-crystal X-ray diffraction data. Raman scattering analysis revealed that the A1g, Eg, and three F2g vibrational modes were observed in the spectra. The signal at ∼382 cm–1, corresponding to the A1g mode, is attributed to symmetrical stretching of the chalcogen bond with respect to the tetrahedral metal. The samples with x = 0.2 and 0.4 exhibited ferromagnetic behavior, characterized by large positive θ values of +261 and +189 K, respectively. In contrast, antiferromagnetic (AF) behavior was observed for CuCrSnS2Se2 with a Néel temperature (TN) of 18.8 K and a θ value of −36.0 K. Density functional theory (DFT) and effective magnetic moments (μeff/μtheo) experimentally measured showed that the Sn ion is in oxidation state of 4+, i.e., diamagnetic behavior. DFT calculations revealed that the most stable magnetic state of CuCr1.0Sn1.0S2Se2 was AF with exchange constants for first- and second-neighbor interactions of J1 = 56.22 cm–1 and J2 = −33.88 cm–1. Thus, the AF interactions between ferromagnetic chains in CuCr1.0Sn1.0S2Se2 originate from the presence of diamagnetic Sn cations.
Fuente
Inorganic Chemistry, 58(20), 13945-13952Link de Acceso
Click aquí para ver el documentoIdentificador DOI
doi.org/10.1021/acs.inorgchem.9b01853Colecciones
La publicación tiene asociados los siguientes ficheros de licencia: