13536-79-3Relevant articles and documents
Spectrum analysis of U3+-doped LaBr3 single crystals. Part 1: Crystal-field analysis
Sobczyk, Marcin,Drozdzynski, Janusz,Karbowiak, Miroslaw
, p. 536 - 544 (2005)
Single crystals of U3+:LaBr3 were grown by the Bridgman-Stockbarger technique. High-resolution polarized absorption spectra of the crystals were recorded at 4.2 K in the 4000-50,000 cm-1 range. Sixty-four experimental crystal-field energy levels of the U3+ ion were fitted to a semiempirical Hamiltonian employing free-ion, one-electron crystal-field as well as two-particle correlation crystal-field (CCF) operators with an r.m.s. deviation of 28 cm-1. The performed analysis of the spectra enabled the determination of crystal-field parameters and assignment of the observed 5f3→5f3 transitions. The effects of selected CCF operators on the splitting of some specific U3+ multiplets have been investigated and the obtained values of Hamiltonian parameters are discussed and compared with those reported in previous analyses.
La6Br10Fe: A La6Fe octahedron with a mixed M6X12/M6X8 type environment
Zheng, Chong,Mattausch, Hansjuergen,Hoch, Constantin,Simon, Arndt
, p. 2356 - 2361 (2008)
The title compound was synthesized from La, LaBr3, and Fe under Ar atmosphere at 800°C. It crystallizes in space group P41 (No. 76) with lattice constants a = 8.255(1) A and c = 30.033(6) A. The structure features an isolated Fe-centered La6 octahedron with all corners, 9 of its 12 edges, and 3 of its 8 triangular faces coordinated, bridged, or capped by Br atoms. The La6Fe octahedron is significantly distorted, and the La coordination by Br atoms deviates from the common close-packing arrangements found in other reduced rare earth metal halides. Band structure, bonding, and physical properties of the compound have been investigated.
Isolated and edge-sharing interstitially stabilized metal tetrahedra {M4Z} in La4ZBr7, M9Z 4I16, and BaM4Z2I8 (M = La,Ce). The nature of Z
Gerlitzki, Niels,Hammerich, Stefanie,Pantenburg, Ingo,Meyer, Gerd
, p. 2024 - 2030 (2006)
Metallothermic reductions of LaBr3, LaI3 and CeI 3 with barium metal resulted in single crystals of La 4ZBr7, M9Z4I16 and BaM4Z2I8 (M = La,Ce) as by-products, subject to apparently ubiquitous oxygen and/or nitrogen (= Z) impurities. The crystal structure of La4ZBr7 (1, orthorhombic, Pnma, Z = 4, a = 1212.4(1), b = 1404.8(2), c = 804.7(1) pm, R 1 = 0.0358 for I>2σI with N:O = 0.91:0.09) is determined by isolated {La4Z} tetrahedra surrounded by and connected through bromide ligands. In the crystal structure of Ce9Z4I 16 (2, orthorhombic, Fddd, Z = 8, a = 890.0(1), b = 2264.1(2), c = 4279.5(4) pm, R1 = 0.0262 for I>2σI with N:O = 0.75:0.25), {Ce4Z} tetrahedra are connected to {Ce4/2Z} chains via common edges and further to layers by iodide ligands. The layers are stacked and connected via the ninth cerium atom according to Ce[{Ce4/2Z}I 4]4. Similar {La4/2Z} chains and BaI 8/4 chains run perpendicularly to each other and are connected via common iodide ions in the crystal structure of BaLa4Z 2I8 = Ba2[{La4/2Z}I 4]4 (3, monoclinic, C2/c, Z = 4, a = 897.5(1), b = 2162.4(3), c = 1229.3(2), β = 110.32(1)°, R1 = 0.0261 for I>2σI with N:O = 0.54:0.46). The nature of the interstitial Z, oxygen and/or nitrogen, is evaluated.
La9Sb16Br3 and Ce9Sb 16Cl3: Stars and stripes in rare earth halide and intermetallic compounds
Zheng, Chong,Mattausch, Hansjuergen,Simon, Arndt
, p. 3684 - 3689 (2005)
The title compounds were synthesized from Ln, LnX3 (Ln = La, Ce; X = Cl, Br), and Sb under an Ar atmosphere at 950°C. They crystallize in the space group P63/m (No. 176) with lattice constants a = 21.232(5) and 20.862(2) A and c = 4.323(2) and 4.2728(7) A for La9Sb 16Br3 and Ce9Sb16Cl3, respectively. The solids are the most metal-rich members in the reduced rare earth metal halide family and contain partial structures which are characteristic of reduced halides and intermetallic phases. These are the [Ln6X6]∞, hexagon stars, Sb-centered [Ln3Sb]∞ trigonal prismatic columns, and stripes of Sb square meshes. Computational analysis indicates that their electronic structure is valence-precise in the reduced halide part, but electron-deficient in the intermetallic part. Susceptibility and resistivity measurements reveal the metallic nature of the compounds.
La4N2S3: A new nitride sulfide of lanthanum with unprecedented crystal structure
Lissner, Falk,Schleid, Thomas
, p. 1167 - 1172 (2006)
The oxidation of lanthanum powder with sulfur and cesium azide (CsN 3) in the presence of lanthanum tribromide (LaBr3) yields lanthanum nitride sulfide with the composition La4N2S 3 when appropriate molar ratios of the reactants are used. Additional cesium bromide (CsBr) as a flux secures fast reactions (7 d) at 900 °C in evacuated silica tubes as well as the formation of almost black single crystals. The orthorhombic crystal structure (Pnnm, Z = 2) was determined from single crystal X-ray diffraction data (a = 641.98(4), b = 1581.42(9), c = 409.87(3) pm). Two crystallographically different La3+ cations are present, La1 resides in sixfold coordination of two N3- and four S2- anions forming a trigonal prism and La2 is coordinated by two N3- and five S2- in the shape of a monocapped trigonal prism. However, the main feature of the crystal structure comprises N3--centred (La 3+)4 tetrahedra which arrange as pairs [N 2La6]12+ of edge-shared [NLa4] 9+ units and which are further connected via four vertices to form double chains ∞1{[N2La 2La′4/2]6+}. They get bundled along [001] like a hexagonal rod packing and are held together by two crystallographically different S2- anions. Further motifs for the connectivity of [NM 4]9+ tetrahedra in crystal structures of nitride chalcogenides and halides of the rare-earth elements (M = Sc, Y, La; Ce - Lu) with ratios of N : M = 1 : 2 are presented and discussed for comparison.
Rare earth ethenide-halides Ln2n+6(C2) n+4X2n+2: Preparation, crystal structure, intergrowth and twinning
Mattausch, Hansjuergen,Kienle, Lorenz,Duppel, Viola,Hoch, Constantin,Simon, Arndt
, p. 1527 - 1535 (2011/01/09)
Preparation, crystal structure, intergrowth and twinning of the compounds La10(C2)6Br6, Ce10(C 2)Br6 and Gd10(C2) 6(Cl6 are described.
