7790-87-6Relevant articles and documents
Disorder in rare earth metal halide carbide nitrides
Schaloske, Manuel C.,Kienle, Lorenz,Mattausch, Hansjuergen,Duppel, Viola,Simon, Arndt
, p. 4049 - 4056 (2011)
Single-crystal X-ray structure determinations of Ce4I 6CN and disordered Ce6I9C2N phases are described together with electron-microscopy studies of Ce6I 9C2N and Y6I9C2N. Ce 4I6CN crystallizes in the tetragonal space group P4 2/mnm with a = 13.877(2) A, c = 9.665(2) A. Compounds β′-Ce6I9C2N and β″- Ce6I9C2N crystallize in space group P6/m with a = 41.774(6) A, c = 13.719(3) A and a = 20.958(3) A, c = 13.793(3) A, respectively. The main structural feature of these compounds are rods of RE6C2 octahedra and RE4N tetrahedra (RE = lanthanide) interconnected in different sequences. These rods are linked into Kagome-type frameworks with additional rods located in the centres of thehexagonal channels. The disorder patterns for these additional rods can be rationalized in terms of nearest-neighbour interactions.
Lanthanide(III) halides: Thermodynamic properties and their correlation with crystal structure
Rycerz,Gaune-Escard
, p. 167 - 174 (2008/10/09)
Temperatures and enthalpies of phase transitions of 17 lanthanide(III) halides determined experimentally are reported. Correlations were made between temperature of fusion of lanthanide(III) halides, on the one hand, and enthalpy of fusion, on the other, versus atomic number of lanthanide. According to this classification, the lanthanide(III) halides split into groups, as also do the corresponding crystal structures. A correlation between the crystal structure of lanthanide(III) halides and their respective entropy of fusion (or entropy of fusion + entropy of solid-solid phase transition) was inferred from the aforementioned features. Fusion in those halides with hexagonal, UCl3-type and orthorhombic, PuBr3-type, structures entails an entropy of fusion change (or entropy of fusion + entropy of solid-solid phase transition change) by 50 ± 4 J mol-1 K-1. The homologous entropy change within the group of halides having the rhomboedric, FeCl3-type, structure, is smaller and equals 40 ± 4 J mol-1 K-1. Halides with monoclinic, AlCl3-type, crystal structure constitute a third group associated to an even smaller entropy change upon fusion, only 31 ± 4 J mol-1 K-1. The halides with lower entropies of fusion also have a lower S1300 K - S298 K indicating either a higher degree of order in the liquid or a higher entropy in the solid at room temperatures.
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 (2008/10/09)
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.
