(Cu)_tet(Cr_2–xSn_x)_octS_4–ySe_y Spinels: Crystal Structure, Density Functional Theory Calculations, and Magnetic Behavior

Abstract

A new series of (Cu) tet [Cr 2−x Sn x ] oct S 4−y Se y compounds was prepared by solid-state reaction at high temperature. Determination of the crystal structures by single-crystal X-ray diffraction revealed that CuCr 1.

RAMAN CHARACTERIZATION OF CuIrSnX4 NORMAL-SPINEL SYSTEMS

“…Figure 4 shows the spectra obtained for each of the phases, and in them, four bands are clearly observed; however, by fitting the spectra with Lorentzian functions, we can perform a more detailed analysis and identify five signals, which are located at the approximate frequencies of 130, 165, 230, 265 and 320 cm -1 . Table 1 summarizes the vibrations observed for the compounds reported in this work and others previously reported by our group for similar solid spinel-type solutions [3], [13].…”

“…The normal spinel-type compounds crystallize in the 𝐹𝑑3 ̅ 𝑚 space group, corresponding to a face-centered cubic structure (fcc) that has an arrangement with a large unit cell, which contains eight units of the formula (8 cations A, 16 cations M and 32 anions X) [6,18]. The structure has 17 vibrational modes, of which five of them are active in Raman,  R = A 1g + E g + 3 F 2g [3], [13], [16][17][18][19].…”

“…Raman spectroscopy is a useful technical to characterize spinel compounds. Several works on thio-and selenospinels have been published in the previous year [2], [3], [12], [13], in which the technique is used to give information about the dependence of the lattice vibrations on the tetrahedral and octahedral cations caused by slight structural distortions.…”

Effects of Tin and Sulfur Chemical Substitution on the Structural and Electrical Properties of CuCr2Se4 Selenospinel

“…For example, replacing metal ions in the octahedral or tetrahedral position with diamagnetic ions can alter the magnetic properties of CuCr2S4 and CuCr2Se4. In (Cu)tet[Cr2-xMx]octSe4 spinels, the substitutions of Cr by M (M = Zr, Sn) have indicated that M is present as a 4 + ion, and Cu as a diamagnetic Cu + ion [3,12]. For CuCr2S4, its physical properties can be understood if its charge distribution is assumed to be Cu + Cr 3+ Cr 4+ S4 8− ; thus, metallic conduction and ferromagnetism are ascribed to the double exchange between Cr 3+ and Cr 4+ [13,14].…”

“…§ cell a parameter obtained from single-crystal analysis of CuCr1.0Sn1.0S2.1Se1.9 was 10.398(2) Å[12].…”