Neue Eisenlanthan‐Oxidsulfid‐ und ‐Oxidselenid‐Phasen mit Schichtstruktur: Fe₂La₂O₃E₂ (E = S, Se)

Abstract

Ein zweidimensionales Netzwerk aus flächenverknüpften FeO2E4‐Oktaedern (E = S, Se), gefolgt von Doppelschichten aus quadratischen E4O4‐Antiprismen, in deren Zentren sich Lanthanatome befinden – so könnte man die ungewöhnliche Schichtstruktur von Fe2La2O3E2‐Phasen (Bild rechts für E = Se) beschreiben. Sowohl das Oxidsulfid als auch das Oxidselenid sind Halbleiter mit interessanten magnetischen Eigenschaften.

Anion Ordering in Bichalcogenides

“…For example, the sulfide-oxide Eu5V3S6O7 [11] contains a weaved net of O and S rows (O/S = 7/6  1) and is best described as a 3-D lattice. Two-dimensional layers of Se and O are found in La2Fe2Se2O3 [12] where the ratio O/Se = 1.5. In Bi2SO2, stacked square layers of either O or S are observed [13] (Figure 1), with the ratio O/S = 2.…”

“…The six-fold coordination has even more possibilities, namely 5+1, 4+2, and 3+3, of which all have several configurational names ( Figure 5). So far, 5+1 has been reported for Cr 3+ [12]. The facial (fac) and the meridional (mer) 3+3 coordinations are still very rare and were almost solely reported for metal-organic complexes, where polydental ligands make it possible to control the fac and mer isomerism.…”

Synthesis and Crystal Structures of Two Novel Niobium Oxo-Selenides: K4Nb2Se11O Consisting of Infinite Anionic Chains and Cs4Nb2Se11O Being the First Example for the Coexistence of Molecular and Infinite Chainlike Transition Metal Polychalcogenide Anions in One Compound

“…2659( 1) 6933( 1) 1865( 1) 39(1) Se( 10) 1024( 1) 9214( 1) 1614( 1) 35(1) Se (11) -615(1) 10518( 1) 2074( 1) 47(1) Se (12) 2850( 1) 13088(1) -1584(1) 34(1) Se (13) 962( 1) 15135(1) -172(1) 26(1) Se (14) 1001( 1) 12726( 1) 1020( 1) 29(1) Se (15) 2968( 1) 11654( 1) 977( 1) 26(1) Se (16) 3751( 1) 14764(1) -300(1) 32(1) Se (17) 4929( 1) 13057(1) -18(1) 28(1) Se (18) 3038( 1) 13944( 1) 1790( 1) 29(1) Se (19) 3048( 1) 12763( 1) 3227( 1) 43(1) Se (20) 5818( 1) 10937( 1) 823( 1) 36(1) Se (21) 5162( 1) 10434( 1) 2777( 1) 47(1) Se (22) 4244( 1 tions are not visible (Figure 1). In the following, only the pentagonal planes and their differences will be discussed.…”

“…Most of the oxyselenides occur in the chemistry of rare earth metals. The known ternary or quaternary rare earth oxyselenides are Ln 2 O 2 Se (Ln = La, Pr, Nd, Sm, Gd, Ho, Er, Yb), Ln 10 Se 14 O (Ln = La, Ce, Pr), La 4 O 4 Se 3 , UOSe, ThOSe, LaGaOSe 2 , La 4 Ga 1.88 O 4 Se 4.82 , LaCrOSe 2 , Ln 2 Ta 3 Se 2 O 8 (Ln = La, Ce, Pr, Nd), Fe 2 La 2 O 3 Se 2 , SmCuSeO, and LnCuSeO (Ln = Gd, Dy) . The only examples for main group or transition metal oxyselenides are Bi 2 O 2 Se, BiCuOSe, and Na 1.9 Cu 2 Se 2 ·Cu 2 O .…”

Synthesis of novel rare earth—Iron oxide chalcogenides with the La2Fe2O3Se2 structure

“…Powder X-ray diffraction data were collected on a Stoe (Ce 2 Fe 2 O 3 S 2 ) and Bruker D8 Advance (Pr 2 Fe 2 O 3 S 2 ) diffractometers (CuKα 1 radiation, Ge(111) monochromator, reflection geometry) Rietveld refinements were performed with the TOPAS package [12] using the fundamental parameter approach as reflection profiles. The structural model proposed by Mayer et al [6] was used for the starting coordinate values. Preferred orientation was corrected using a spherical harmonics approach developed in TOPAS.…”