MgCuAl2-type Intermetallics REPdCd2(RE = Ce, Pr, Nd, Sm)

2012 ◽  
Vol 67 (11) ◽  
pp. 1221-1224 ◽  
Author(s):  
Michael Johnscher ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Intermetallic Compounds ◽  
High Frequency ◽  
Three Dimensional ◽  
Type Structure ◽  
Subsequent Annealing ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Structure Factors

The cadmium-rich intermetallic compounds REPdCd2 (RE=Ce, Pr, Nd, Sm) were obtained by high-frequency melting of the elements in sealed niobium ampoules and subsequent annealing in muffle furnaces. The REPdCd2 phases crystallize with the orthorhombic MgCuAl2-type structure, space group Cmcm. The structure of NdPdCd2 was refined from single-crystal X-ray diffractometer data: a=421.9(3), b=995.4(7), c=834.5(6) pm, wR=0.0286, 451 structure factors, 16 variables. The palladium and cadmium atoms build up a three-dimensional [PdCd2] network (281 - 283 pm Pd-Cd; 298 - 335 pm Cd-Cd) in which the neodymium atoms fill cavities. They are connected to the [PdCd2] network via shorter Nd-Pd bonds of 286 pm.

Rare Earth-rich Cadmium Compounds RE4TCd (T = Ni, Pd, Ir, Pt)

2008 ◽  
Vol 63 (9) ◽  
pp. 1127-1130 ◽  
Author(s):  
Falko M. Schappacher ◽  
Ute Ch. Rodewald ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Transition Metal ◽  
Single Crystal ◽  
Intermetallic Compounds ◽  
Three Dimensional ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Cadmium Compounds

New intermetallic compounds RE4TCd (RE = Y, La-Nd, Sm, Gd-Tm, Lu; T = Ni, Pd, Ir, Pt) were synthesized by melting of the elements in sealed tantalum tubes in a highfrequency furnace. They crystallize with the Gd4RhIn-type structure, space group F 4̄3m, Z = 16. The four gadolinium compounds were characterized by single crystal X-ray diffractometer data: a = 1361.7(1) pm, wR2 = 0.062, 456 F2 values, 19 variables for Gd4NiCd; a = 1382.1(2) pm, wR2 = 0.077, 451 F2 values, 19 variables for Gd4PdCd; a = 1363.6(2) pm, wR2 = 0.045, 494 F2 values, 19 variables for Gd4IrCd; a = 1379.0(1) pm, wR2 = 0.045, 448 F2 values, 19 variables for Gd4PtCd. The rare earth atoms build up transition metal-centered trigonal prisms which are condensed via common corners and edges, leading to three-dimensional adamantane-related networks. The cadmium atoms form Cd4 tetrahedra which fill voids left in the prisms’ network.

Rare Earth-rich Cadmium Compounds RE23T7Cd4 (T = Co, Ni, Ru, Rh, Ir, Pt)

2009 ◽  
Vol 64 (2) ◽  
pp. 184-188 ◽  
Author(s):  
Frank Tappe ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Transition Metal ◽  
Single Crystal ◽  
Intermetallic Compounds ◽  
High Frequency ◽  
Three Dimensional ◽  
Type Structure ◽  
Interatomic Distances ◽  
X Ray ◽  
Structure Space

The rare earth-rich intermetallic compounds RE23T7CD4(RE = La-Nd, Sm, Gd, Tb; T = Co, Ni, Ru, Rh, Ir, Pt) were synthesized by melting of the elements in sealed tantalum tubes in a high frequency furnace. They crystallize with the Pr23Ir7Mg4-type structure, space group P63mc, Z = 2. The structures of La23Pt7Cd4 (a = 1025.4(2), c = 2319.5(5) pm, wR2 = 0.0425, 2587 F2, 74 variables), La23Ru6.87(1)Cd4 (a = 1015.0(2), c = 2282.8(4) pm, wR2 = 0.0383, 2459 F2, 75 variables), and Nd23Rh7Cd4 (a = 990.0(2), c = 2239.0(5) pm, wR2 = 0.0507, 2350 F2, 74 variables) were refined from single crystal X-ray diffractometer data. Central structural motifs of the RE23 T7Cd4 compounds are transition metal-centered trigonal prisms of rare earth atoms and Cd4 tetrahedra. The RE6T prisms are condensed via common edges and corners, leading to three-dimensional networks. Typical interatomic distances in the prismatic network and in the Cd4 tetrahedra are 295 - 313 pm La-Pt and 319 - 325 pm Cd-Cd, respectively (examplarily for La23Pt7Cd4)

CaPtIn4 – an intergrowth variant of CaPtIn2 and indium slabs

2019 ◽  
Vol 74 (9) ◽  
pp. 693-698 ◽  
Author(s):  
Birgit Heying ◽  
Jutta Kösters ◽  
Rainer Pöttgen
Keyword(s):  
Intermetallic Compound ◽  
Single Crystal ◽  
Peritectic Reaction ◽  
Three Dimensional ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Indium Metal

AbstractThe indium-rich intermetallic compound CaPtIn4 is formed in a peritectic reaction of CaPtIn2 and indium metal at T = 670 K (14 days annealing). CaPtIn4 crystallizes with the YNiAl4-type structure, space group Cmcm, which was refined from single crystal X-ray diffractometer data: a = 446.3(5), b = 1659.50(18), c = 756.8(8) pm, wR2 = 0.0646, 640 F2 values and 24 variables. Geometrically one can describe the CaPtIn4 structure as an intergrowth variant of CaPtIn2 (MgCuAl2 type) and indium slabs. The three-dimensional [PtIn4] polyanionic network shows short Pt–In distances of 269–280 pm and a broader range of In–In distances (304–378 pm) within substantially distorted In@In8 cubes.

Intermetallic Compounds RETMg2 (RE = La, Pr, Nd; T = Ni, Pd, Pt) with MgCuAl2-type Structure

2011 ◽  
Vol 66 (6) ◽  
pp. 651-653 ◽  
Author(s):  
Marcel Kersting ◽  
Rainer Pöttgen
Keyword(s):  
Intermetallic Compounds ◽  
Type Structure ◽  
Subsequent Annealing ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Structure Space

The magnesium-rich intermetallic compounds RETMg2 (RE = La, Pr,Nd; T = Ni, Pd, Pt) were obtained by melting of the elements in sealed tantalum ampoules and subsequent annealing. Their structures have been characterized on the basis of powder X-ray diffraction. The RETMg2 phases crystallize with the orthorhombic MgCuAl2-type structure, space group Cmcm. The crystal chemical peculiarities are briefly discussed.

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.

Gold-Tin Ordering in SrAu2Sn2

2014 ◽  
Vol 69 (7) ◽  
pp. 767-774 ◽  
Author(s):  
Christian Schwickert ◽  
Birgit Gerke ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Coordination Number ◽  
Solid Solutions ◽  
High Frequency ◽  
Spectroscopic Data ◽  
Type Structure ◽  
Temperature Dependent ◽  
Space Group ◽  
X Ray ◽  
Structure Space

Samples of the solid solutions SrAuxSn4−x (1:7 ≤ x ≤ 2:2) were obtained by high-frequency melting of the elements in sealed niobium ampoules. Powder and single-crystal X-ray data confirmed the CaBe2Ge2-type structure, space group P4/nmm. The structures of SrAu1.76Sn2.24, SrAu2Sn2, SrAu2.16Sn1.84 (crystal A), SrAu2.16Sn1.84 (crystal B), and SrAu2.22Sn1.78 were refined from singlecrystal diffractometer data. Only the SrAu2Sn2 crystal shows complete Au-Sn ordering while all other crystals show substantial mixed occupancies on the four crystallographically independent sites of the polyanionic networks in which the strontium atoms fill cages of coordination number 16. Temperature-dependent susceptibility measurements have revealed diamagnetism for SrAu2Sn2. 119Sn Mössbauer spectroscopic data of a bulk SrAu2Sn2 sample have resolved the tetrahedral and square-pyramidal tin sites but point to substantial Au-Sn disorder.

scholarly journals Intermetallic REPtZn Compounds with TiNiSi-type Structure

2011 ◽  
Vol 66 (7) ◽  
pp. 671-676 ◽  
Author(s):  
Trinath Mishra ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Coordination Number ◽  
High Frequency ◽  
Three Dimensional ◽  
Type Structure ◽  
Rare Earth Compounds ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray

The equiatomic rare earth compounds REPtZn (RE = Y, Pr, Nd, Gd-Tm) were synthesized from the elements in sealed tantalum tubes by high-frequency melting at 1500 K followed by annealing at 1120 K and quenching. The samples were characterized by powder X-ray diffraction. The structures of four crystals were refined from single-crystal diffractometer data: TiNiSi type, Pnma, a = 707.1(1), b = 430.0(1), c = 812.4(1) pm, wR2 = 0.066, 602 F2, 21 variables for PrPt1.056Zn0.944; a = 695.2(1), b = 419.9(1), c = 804.8(1) pm, wR2 = 0.041, 522 F2, 21 variables for GdPt0.941Zn1.059; a = 688.2(1), b = 408.1(1), c = 812.5(1) pm, wR2 = 0.041, 497 F2, 22 variables for HoPt1.055Zn0.945; a = 686.9(1), b = 407.8(1), c = 810.4(1) pm, wR2 = 0.061, 779 F2, 20 variables for ErPtZn. The single-crystal data indicate small homogeneity ranges REPt1±xZn1±x. The platinum and zinc atoms build up three-dimensional [PtZn] networks (265 - 269 pm Pt-Zn in ErPtZn) in which the erbium atoms fill cages with coordination number 16 (6 Pt + 6 Zn + 4 Er). Bonding of the erbium atoms to the [PtZn] network proceeds via shorter RE-Pt distances, i. e. 288 - 293 pm in ErPtZn.

Copper-rich Intermetallic Compounds RECu9Cd2(RE = La, Ce, Pr, Nd) with YNi9In2-type Structure

2012 ◽  
Vol 67 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Michael Johnscher ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Intermetallic Compounds ◽  
Induction Furnace ◽  
Three Dimensional ◽  
Pair Formation ◽  
Type Structure ◽  
X Ray Diffraction ◽  
X Ray

The YNi9In2-type copper-rich compounds RECu9Cd2 (RE=La, Ce, Pr, Nd) were synthesized directly from the elements in sealed niobium ampoules in an induction furnace and were characterized by powder X-ray diffraction. The structure of PrCu9Cd2 was refined from single-crystal Xray diffractometer data: P4/mbm, a=849.0(3), c=498.2(3) pm, wR2=0.0418, 374 F2 values, 23 variables. The structure has two striking polyhedral motifs: Pr@Cu16Cd4 and Cu2@Cu8Cd4. The packing of these polyhedra describes the whole structure. The copper and cadmium atoms build up a three-dimensional [Cu9Cd2] network with broader ranges of Cu-Cu (246 - 274 pm) and Cu-Cd (272 - 288 pm) distances. The cadmium atoms show segregation through pair formation with Cd-Cd distances of 288 pm.

The Stannides EuPdSn and EuPtSn

1996 ◽  
Vol 51 (6) ◽  
pp. 806-810 ◽  
Author(s):  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Crystal Chemistry ◽  
Three Dimensional ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray

Abstract EuPdSn and EuPtSn were prepared from the elements in tantalum tubes at 1070 K and investigated by X-ray diffraction on both powder as well as single crystals. They crystallize with the TiNiSi type structure of space group Pnma and with Z = 4 formula units per cell. Both structures were refined from single-crystal diffractometer data: a = 751.24(9), b = 469.15(6), c = 804.31(9) pm, V = 0.2835(1) nm3 for EuPdSn, and a = 753.38(7), b = 467.72(4), c = 793.08(7) pm, V = 0.2795(1) nnr for EuPtSn. The structures consist of three-dimensional [PdSn] and [PtSn] polyanionic networks in which the europium atoms are embedded. The crystal chemistry of these stannides is briefly discussed

Notizen: Die Kristallstruktur von Calciumchromat(VI), CaCrO4 / The Crystal Structure of Calcium Chromate (VI), CaCrO4

1996 ◽  
Vol 51 (5) ◽  
pp. 751-753 ◽  
Author(s):  
Gabriele Weber ◽  
Klaus-Jürgen Range
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Three Dimensional ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Zircon Type

The zircon-type structure of calcium chromate( VI), CaCrO4, has been confirmed and refined from single-crystal X-ray data. The compound crystallizes tetragonaly, space group I41/amd, with a = 7.222(2), c = 6.285(1) Å, c/a = 0.8703 and Z = 4. The structure comprises isolated, slightly distorted CrO4 tetrahedra ( C r-O = 1.646(3) Å ) which are connected with CaO8 dodecahedra (<Ca-O> = 2.556 Å) by edge- and corner-sharing. The three-dimensional framework thus created contains rather large holes which are, however, empty in the case of CaCrO4

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