The Crystal Structures of Re2Al, Re4Al11, and ReAl6

1993 ◽  
Vol 48 (12) ◽  
pp. 1767-1773 ◽  
Author(s):  
Sabine Niemann ◽  
Wolfgang Jeitschko
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Type Structure ◽  
Variable Parameters ◽  
X Ray ◽  
Lattice Constants ◽  
Structure Factors ◽  
Pauli Paramagnetism

Well-crystallized samples of the rhenium aluminides Re4Al11 and ReAl6 were obtained by reaction of rhenium with an excess of aluminum. Re4Al11 was found to be isotypic with Mn4Al11. The MnAl6 type structure of ReAl6 was confirmed. The crystal structures of both compounds were refined from single-crystal X-ray data. Re4Al11:P1̄, Z = 1, a = 516.0(1) pm, b = 896.3(2) pm, c = 516.9(1) pm, a = 90.44(1)°, β = 99.76(1)°, γ = 105.17(1)°, V = 0.2271 nm3, R = 0.036 for 2315 structure factors and 74 variable parameters. ReAl6: Cmcm, Z = 4, a = 761.0(1) pm, b = 660.5(1) pm, c = 903.4(1) pm, V = 0.4541 nm3, R = 0.013 for 711F values and 23 variables. In both structures the rhenium atoms have ten aluminum neighbors at distances from 245 to 277 pm. The Al-Al distances cover the whole range from 251 to 362 pm rather continuously. The previously reported compound Re2Al with the tetragonal MoSi2-type structure has the lattice constants a = 298.1(1) pm, c = 958.4(4) pm, V = 0.08519 nm3. ReAl6 shows Pauli-paramagnetism.

The Lanthanoid Osmium Gallides Er2Os3Ga10 and Tm2Os3Ga10 with Yb2Ru3Ga10-type Structure

2009 ◽  
Vol 64 (5) ◽  
pp. 499-503 ◽  
Author(s):  
Wolfgang Jeitschko ◽  
Martin Schlüter
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Intermetallic Compounds ◽  
High Frequency ◽  
Type Structure ◽  
Variable Parameters ◽  
X Ray ◽  
Lattice Constants

The title compounds were prepared by melting and annealing of stoichiometric mixtures of the elemental components in a high-frequency furnace. They are isotypic with Yb2Ru3Ga10 (P4/mbm, Z = 2). Their lattice constants were determined from X-ray powder data, and their crystal structures were refined from single-crystal X-ray data. Er2Os3Ga10: a = 883.4(1), c = 636.7(1) pm, R = 0.025 for 506 Fo values, and Tm2Os3Ga10: a = 883.2(1), c = 633.6(1) pm, R = 0.023 for 568 Fo values and 25 variable parameters each. The crystal structures of these intermetallic compounds are briefly discussed.

Quaternary Equiatomic Compounds LnZnSbO (Ln = La - Nd, Sm) with ZrCuSiAs-Type Structure

1997 ◽  
Vol 52 (12) ◽  
pp. 1467-1470 ◽  
Author(s):  
Petra Wollesen ◽  
Joachim W. Kaiser ◽  
Wolfgang Jeitschko
Keyword(s):  
Zinc Oxide ◽  
Single Crystal ◽  
Chemical Bonding ◽  
Type Structure ◽  
Variable Parameters ◽  
X Ray ◽  
Structure Factors ◽  
Cold Pressed

Abstract The five compounds LnZnSbO (Ln = La - Nd, Sm) were prepared by annealing cold-pressed pellets of the lanthanoids, zinc oxide, and antimony, or by reacting these components in a NaCl/KCl flux. They crystallize with the tetragonal ZrCuSiAs type structure, which was refined from single-crystal X-ray data of CeZnSbO : P 4/nmm, a = 419.76(4), c = 947.4(1) pm, Z = 2, R = 0.022 for 165 structure factors and 12 variable parameters. Chemical bonding in this and the formally isotypic compound CeZn1-xSb2 is briefly discussed.

Dimorphic ThNi2P2 with BaCu2S2 and CaBe2Ge2 Type Structure

1994 ◽  
Vol 49 (8) ◽  
pp. 1074-1080 ◽  
Author(s):  
Jörg H. Albering ◽  
Wolfgang Jeitschko
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Crystal Structures ◽  
Type Structure ◽  
Variable Parameters ◽  
Higher Symmetry ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
High Temperature Form

Two modifications of ThNi2P2 were prepared in a tin flux at 850 °C (α-ThNi2P2) and 1000 °C (β-ThNi2P2). The crystal structures of both modifications were refined from single­crystal X-ray data. α-ThNi2P2 (BaCu2S2 type structure): Pnma. a = 819.69(5), b = 394.28(3), c = 981.54(7) pm. R = 0.028 for 32 variables and 654 structure factors: β-ThNi2P2 (CaBe2Ge2 type structure): P4/nmm, a = 408.5(1), c = 908.0(3) pm, R = 0.033 for 15 variable parameters and 261 F values. Although the two structures are closely related, they can be transformed into each other only by a reconstructive phase transformation. The differences and similari­ties of the two structures are discussed. The high temperature form has higher symmetry, a smaller number of variable positional parameters, and a tendency for higher coordination numbers.

Quaternary Equiatomic Manganese Pnictide Oxides AMnPO (A = La-Nd, Sm, Gd-Dy), AMnAsO (A = Y, La-Nd, Sm, Gd-Dy, U), and AMnSbO (A = La-Nd, Sm, Gd) with ZrCuSiAs Type Structure

1997 ◽  
Vol 52 (5) ◽  
pp. 560-564 ◽  
Author(s):  
Andre T. Nientiedt ◽  
Wolfgang Jeitschko ◽  
Peter G. Pollmeier ◽  
Markus Brylak
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Single Crystal ◽  
Chemical Bonding ◽  
Type Structure ◽  
Variable Parameters ◽  
X Ray ◽  
Structure Factors ◽  
The Rare Earth

Abstract The 24 title compounds were prepared in well crystallized form by reaction of the rare earth elements (or uranium, respectively), manganese, the pnictide components, and MnO2 in a NaCl/KCl flux. They crystallize with the tetragonal ZrCuSiAs type structure (P4/nmm, Z = 2), which has been refined from single-crystal X-ray data of NdMnPO (a = 398.9(1), c = 867.4(1) pm, R = 0.026), NdMnAsO (a = 404,9(2), c = 889.3(4) pm, R = 0.025), and NdMnSbO (a = 416.5(1), c = 946.2(2) pm, R = 0.021) for 107, 190, and 124 structure factors, respectively, and 11 variable parameters each. Chemical bonding in these compounds is briefly discussed.

Preparation and Crystal Structure of the Isotypic Carbides Ln3.67TC6 (Ln = rare earth elements; T = Mn, Fe, Ru) and Eu3,16NiC6

1996 ◽  
Vol 51 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Anne M. Witte ◽  
Wolfgang Jeitschko
Keyword(s):  
Crystal Structure ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Single Crystal ◽  
Crystal Structures ◽  
Variable Parameters ◽  
X Ray ◽  
Arc Melting ◽  
Structure Factors

Abstract The 14 carbides Ln3.67MnC6 (Ln = La-Nd) and Ln3.67TC6 (Ln = La-Nd, Sm; T = Fe, Ru) were prepared from the elemental components by arc-melting and subsequent annealing. Eu3.16NiC6 was obtained from a lithium flux. The crystal structures of these nearly isotypic, hexagonal compounds (P63/m, Z = 2) were determined from single-crystal X-ray data; La3.67- FeC6: a = 878.7(2), c = 535.1(1) pm, R = 0.052 for 548 structure factors and 25 variable parameters; Eu3.16NiC6: a -860.0(1), c = 548.2(2) pm, R = 0.015 for 606 structure factors and 25 variables. The structures differ from the previously reported Gd3Mn2C6 structure by the occupancy of one manganese position by rare earth atoms. Since the lanthanum atoms are larger than the manganese atoms, only two thirds of these manganese positions can be occupied by the lanthanum atoms in La3.67FeC6. Eu3.16NiC6 has similar atomic positions. The C-C bond distances in the C2 pairs are 130(2) and 126.5(5) pm in the La and Eu compounds, respectively. Magnetic susceptibility measurements with a SQUID magnetometer indicate La3.67FeC6 to be Pauli paramagnetic. A test for superconductivity was negative down to 3 K.

Quaternary Phosphide Oxides Pr3Cu4P4O2–x and Sm3Cu4P4O2–x with Ordered Zr3Cu4Si6-Type Structure

2002 ◽  
Vol 57 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Joachim W. Kaiser ◽  
Wolfgang Jeitschko
Keyword(s):  
Single Crystal ◽  
Chemical Bonding ◽  
Empirical Formula ◽  
Type Structure ◽  
Formula Unit ◽  
Variable Parameters ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Structure Factors

The compounds Ln3Cu4P4O2-χ (Ln = Pr, Sm) were prepared by annealing the elemental components in a NaCl/KCl flux. They crystallize with an ordered Zr3Cu4Si6-type structure (space group I4/mmm, Z = 2), which was refined from single-crystal X-ray data for both compounds; Pr3Cu4P4O2-χ: a = 397.8(1), c = 2658.7(3) pm, R = 0.046 for 235 structure factors and 19 variable parameters; Sm3Cu4P4O2-χ: a = 392.8(1), c = 2643.6(3) pm, R = 0.057 for 145 F values and 19 variables. The refinements showed partial occupancy for the oxygen positions resulting in approximately 1.5 oxygen atoms per formula unit. Half of the phosphorus atoms form pairs with typical two-electron bond distances of 222.8(4) and 221.7(8) pm, respectively. Using oxidation numbers chemical bonding in these phosphide oxides can be rationalized with the formula (Ln+3)3(Cu+1)4(P-P)-4(P-3)2(O-2)1.5. Hence, the empirical formula may also be doubled (Ln6Cu8P8O3), and the compounds are expected to be semiconducting.

Strukturvarianten des MgCu2-Typs: Die Verbindungen Mg2Ni3P und Mg2Ni3As / Variants of the MgCu2 Type: The Compounds Mg2Ni3P and Mg2Ni3As

1992 ◽  
Vol 47 (10) ◽  
pp. 1351-1354 ◽  
Author(s):  
Viktor Keimes ◽  
Albrecht Mewis
Keyword(s):  
Single Crystal ◽  
Homogeneity Range ◽  
Hexagonal Lattice ◽  
Structure Type ◽  
Type Structure ◽  
X Ray ◽  
Lattice Constants ◽  
Metal Atoms ◽  
Rhombohedral Symmetry

The compounds Mg2Ni3P and Mg2Ni3As were prepared by heating the elements. Their structures have been determined from single-crystal X-ray data. The structure of the phosphide is a rhombohedral ternary variant of the cubic Laves structure type MgCu2 (R 3̄ m; hexagonal lattice constants: a = 4.971(0) Å, c = 10.961(2) Å). The ordered substitution of one quarter of the metal atoms by phosphorus and the resulting shorter distances are responsible for the rhombohedral symmetry.The arsenide crystallizes in the MgCu2 type structure (Fd 3 m; a = 6.891(1)A, composition Mg2Ni3As) with a statistic distribution of the Ni and As atoms; the relevant homogeneity range extends from Mg2Ni2.9As1.1 to Mg2Ni3.5As0.5.

Er5Re2C7, Tm5Re2C7, and Lu5Re2C7 with Sc5Re2C7 Type, and Yb2ReC2 with Pr2ReC2 Type Structures

1997 ◽  
Vol 52 (2) ◽  
pp. 231-236 ◽  
Author(s):  
R. Pöttgen ◽  
K. H. Wachtmann ◽  
W. Jeitschko ◽  
A. Lang ◽  
T. Ebel
Keyword(s):  
Magnetic Susceptibility ◽  
Bond Length ◽  
High Frequency ◽  
Annealing Process ◽  
Type Structure ◽  
The Other ◽  
Variable Parameters ◽  
X Ray ◽  
Arc Melting ◽  
Structure Factors

Abstract Er5Re2C7, Tm5Re2C7, and Lu5Re2C7 were prepared by arc-melting of the elemental components and subsequent annealing at 800 °C. Er5Re2C7 forms only after the annealing process, whereas the other two carbides were already present in the as cast samples. They crystallize with a Sc5Re2C7 type structure, which was refined from single-crystal X-ray data of Lu5Re2C7: Cmmm, a = 791.44(5), b = 1418.08(8), c = 332.79(2) pm, Z = 2, R = 0.037 for 544 structure factors and 21 variable parameters. The structure contains linear centrosymmetric C3 units with a C-C bond length of 133(2) pm and isolated carbon atoms in octahedral coordination of four lutetium and two rhenium atoms. The rhenium atoms within the two-dimensionally infinite polymeric sheets [Re2C4]n are electronically saturated as is indicated by the diamagnetism and the semiconductivity of this carbide. Yb2ReC2 was prepared by reacting the elements in a sealed tantalum tube with a high-frequency furnace. It crystallizes with a Pr2ReC2 type structure: Pnma, a = 645.91(6), b = 498.64(6), and c = 966.05(6) pm. Magnetic susceptibility measurements indicate the ytterbium atoms to be trivalent in this compound.

Über die Kristallstrukturen der Tellurate Pb3Fe2Te2O12 und Pb2CoTeO6 / On the Crystal Structures of the Tellurates Pb3Fe2Te2O12 and Pb2CoTeO6

1997 ◽  
Vol 52 (1) ◽  
pp. 35-39 ◽  
Author(s):  
B. Wedel ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Negative Charge ◽  
X Ray ◽  
Space Groups ◽  
Lattice Constants ◽  
Coulomb Term ◽  
Lone Pairs ◽  
Symmetry Space

Pb3Fe2Te2O12 (I) and Pb2CoTeO6 (II) have been prepared by crystallization from melts. Single crystal X-ray investigations led to monoclinic (I) and tetragonal (II) symmetry, space groups C4s-Cc and D174h-14/mmm. Lattice constants I: a = 9.866(3), b = 15.332(4), c = 7.172(2) Å, β = 111.34(3)°, Z = 4. II: a = 5.661(5), c = 8.004(7) Å, Z = 2. (I) represents a new crystal structure, characterized by a network of octahedra occupied by Fe3+ and Te6+ in a disordered manner. The centres of negative charge of the lone pairs of Pb2+ in I are estimated by Coulomb term calculations. II belongs to the elpasolithe type

Ternary Intermetallic Compounds LnMn2Al10 (Ln = Y, La-Nd, Sm, Gd-Dy) and LnRe2Al10 (Ln = Ce, Pr, Sm) with CaCr2Al10-Type Structure

1998 ◽  
Vol 53 (7) ◽  
pp. 673-678 ◽  
Author(s):  
Verena M.T. Thiede ◽  
Wolfgang Jeitschko
Keyword(s):  
Transition Metal ◽  
Type Structure ◽  
Variable Parameters ◽  
X Ray ◽  
Metal Atoms ◽  
Transition Metal Atoms ◽  
Structural Relationships ◽  
Structure Factors ◽  
Ternary Intermetallic Compounds ◽  
First Time

Abstract The twelve title compounds have been prepared for the first time. Their CaCr2Al10-type structure (P4/nmm, Z = 4) was refined from single-crystal X-ray data for the three representatives TbMnAl10 (a = 1274.3(2) pm, c = 511.4(2) pm, R = 0.025 for 680 structure factors F and 43 variable parameters V), CeRe2Al10 (a = 1295.5(5) pm, c = 517.2(4) pm, R = 0.054 for 810 F and 46 V), and SmRe2Al10 (a = 1291.5(2) pm, c = 516.5(1) pm, R = 0.021 for 622 F and 46 V). The atomic positions of the lanthanoid and transition metal atoms are fully occupied. Significant deviations from the full occupancies were observed for two aluminum sites in TbMn2Al10 and for all five aluminum sites of the two rhenium-containing compounds, resulting in the compositions TbMn2Al9.63(2), CeRe2Al9.52(8), and SmRe2Al9.16(9). The cell volume of CeRe2Al10 and to a smaller extent also that of CeMn2Al10 indicate mixed or intermediate +III/+IV valencies of the cerium atoms in these compounds. The structural relationships between the three closely related body-centered tetragonal structures of ThMn12, CeMniAl8, DyFe6Al6 and the primitive tetragonal structure of CaCr2Al10 are briefly discussed.

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