Quaternary Selenides EuLnCuSe3: Synthesis, Structures, Properties and In Silico Studies

Abstract

In this work, we report on the synthesis, in-depth crystal structure studies as well as optical and magnetic properties of newly synthesized heterometallic quaternary selenides of the Eu+2Ln+3Cu+1Se3 composition. Crystal structures of the obtained compounds were refined by the derivative difference minimization (DDM) method from the powder X-ray diffraction data. The structures are found to belong to orthorhombic space groups Pnma (structure type Ba2MnS3 for EuLaCuSe3 and structure type Eu2CuS3 for EuLnCuSe3, where Ln = Sm, Gd, Tb, Dy, Ho and Y) and Cmcm (structure type KZrCuS3 for EuLnCuSe3, where Ln = Tm, Yb and Lu). Space groups Pnma and Cmcm were delimited based on the tolerance factor t’, and vibrational spectroscopy additionally confirmed the formation of three structural types. With a decrease in the ionic radius of Ln3+ in the reported structures, the distortion of the (LnCuSe3) layers decreases, and a gradual formation of the more symmetric structure occurs in the sequence Ba2MnS3 → Eu2CuS3 → KZrCuS3. According to magnetic studies, compounds EuLnCuSe3 (Ln = Tb, Dy, Ho and Tm) each exhibit ferrimagnetic properties with transition temperatures ranging from 4.7 to 6.3 K. A negative magnetization effect is observed for compound EuHoCuSe3 at temperatures below 4.8 K. The magnetic properties of the discussed selenides and isostructural sulfides were compared. The direct optical band gaps for EuLnCuSe3, subtracted from the corresponding diffuse reflectance spectra, were found to be 1.87–2.09 eV. Deviation between experimental and calculated band gaps is ascribed to lower d states of Eu2+ in the crystal field of EuLnCuSe3, while anomalous narrowing of the band gap of EuYbCuSe3 is explained by the low-lying charge-transfer state. Ab initio calculations of the crystal structures, elastic properties and phonon spectra of the reported compounds were performed.

Crystal-Structure Prediction and Experimental Investigation of the Polymorphic Lanthanum Fluoride Selenides LaFSe and La2F4Se

“…The effective core pseudopotential (ECP) labeled La ECP Heifets 2013 for lanthanum , was used, together with the all-electron basis set (AEBS)-labeled Se_976-311d51G_towler_1995 for selenium , and AEBS-labeled F_7-311G_nada_1993 for fluorine. , The labels of the special points of the Brillouin zones of the calculated band structures correspond to those of a tetragonal (P) lattice in the case of A-LaFSe, to the hexagonal (H) lattice in the case of the B- and C-LaFSe phases, and to the tetragonal (BC) lattice for D-LaFSe, respectively.…”

A Challenge toward Novel Quaternary Sulfides SrLnCuS3 (Ln = La, Nd, Tm): Unraveling Synthetic Pathways, Structures and Properties

“…Layered chalcogenides containing d -metals are of particular interest due to their valuable properties, as well as being used as superconductors [ 1 ], magnetic [ 2 , 3 ] and thermoelectric materials [ 4 ], materials for infrared and nonlinear optics [ 5 , 6 , 7 ] and catalysts [ 8 ]. The quaternary chalcogenides ABCX 3 (A is an alkali or alkaline earth metal, Eu; B is a d - or f -element; C is a d -element; X is a chalcogenide) produce layered and/or channel structures, crystallizing in various structural types [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. An overwhelming majority of the crystal structures of ABCX 3 exhibit 2D anionic layers [BCX 3 ] n− with trapped A n+ cations.…”

“…Thus, thermodynamically stable quaternary compounds are potential high-performance thermoelectrics, thermal barrier coatings, and thermal data-storage devices [ 26 , 29 , 30 , 31 , 32 ]. Furthermore, semiconductor, magnetic, optical, and thermodynamic properties have also been described for these compounds [ 4 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 23 , 24 , 33 , 34 , 35 , 36 , 37 , 38 ].…”

“…The isostructural quaternary sulfides EuLnCuS 3 [ 37 , 49 ] and selenides EuLnCuSe 3 [ 23 ] and SrLnCuSe 3 [ 50 , 51 ] always start to crystallize in the structural type Ba 2 MnS 3 . Due to the similar ionic radii of Eu 2+ and Sr 2+ (1.17 and 1.18 Å, respectively [ 52 ]), the structural types of EuLnCuS 3 and SrLnCuS 3 should also be similar.…”

“…In all the listed compounds, the Eu 2+ and Ln 3+ ions occupy two crystallographically independent positions. The change of space group from Pnma to Cmcm occurs between SrYCuS 3 and SrErCuS 3 [ 23 ]. SrLnCuS 3 melt incongruently at 1429–1712 K [ 34 , 43 ].…”