Synthesis and Structure of NbPdSi

2006 ◽  
Vol 61 (3) ◽  
pp. 339-341 ◽  
Author(s):  
Martin Valldor ◽  
Rainer Pöttgen

Abstract The new silicide NbPdSi was prepared by melting the elements in an arc-furnace.Well-shaped single crystals were obtained by annealing the sample in an induction furnace. The structure of NbPdSi has been studied by X-ray powder and single crystal diffractometer data: TiNiSi type, Pnma, Z = 4, a=643.0(1), b=376.7(1), c=744.4(2) pm, wR2=0.0330, 346 F2 values, and 20 variables. The palladium and silicon atoms build up a three-dimensional [PdSi] network where each palladium atoms has a strongly distorted tetrahedral silicon coordination at Pd-Si ranging from 242 to 250 pm. The niobium atoms fill channels left in the [PdSi] network.

2014 ◽  
Vol 69 (6) ◽  
pp. 674-680 ◽  
Author(s):  
Christian Schwickert ◽  
Rainer Pöttgen

The intermetallic zinc compounds CaAuZn, SrPdZn, SrPtZn, SrAuZn, BaPd1.57 Zn3.43, and BaAu1.41Zn3.59 were synthesized from the elements in sealed niobium ampoules in an induction furnace. The equiatomic compounds crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. Single-crystal X-ray data exhibited small degrees of Au=Zn mixing within the three-dimensional [AuZn] networks and resulted in the compositions CaAu1.02Zn0.98 and SrAu1.03Zn0.97 for two investigated single crystals. BaPd1.57 Zn3.43 and BaAu1.41 Zn3.59 adopt partially ordered versions of the LT-SrZn5 type, space group Pnma. Both structures were refined on the basis of X-ray single-crystal diffractometer data. a=1331.13(6), b=531.45(3), c=682.20(4) pm, wR=0.0245, 1138 F2 values, 39 variables for BaPd1.57Zn3.43 and a=1344.35(2), b=537.47(2), c=691.22(4) pm, wR=0.0441, 931 F2 values, 37 refined variables for BaAu1.41Zn3.59. The transition metal and zinc atoms form a complex three-dimensional network of (T, Zn)4 tetrahedra which are condensed via common corners and T/Zn-T/Zn bonds. Large cavities within these networks are filled by the barium atoms which have coordination number 19, i. e. Ba@(T, Zn)17Ba2.


2019 ◽  
Vol 74 (5) ◽  
pp. 443-449 ◽  
Author(s):  
Birgit Heying ◽  
Jutta Kösters ◽  
Rainer Pöttgen

AbstractRod-shaped single crystals of Sr4Pt10In21were prepared from the elements in glassy-carbon crucibles in a high-frequency furnace. The structure of Sr4Pt10In21was refined from single-crystal X-ray diffractometer data:C2/m, Ho4Ni10Ga21type,a = 2322.62(7),b = 450.27(2),c = 1958.09(7) pm,β = 133.191(3)°,wR = 0.0464, 3200F2values and 107 variables. The three-dimensional [Pt10In21]δ−polyanionic network is stabilized through substantial Pt–In (269–313 pm Pt–In) and In–In (294–362 pm In–In) bonding. All platinum atoms have slightly distorted tri-capped trigonal prismatic coordination and the two crystallographically independent strontium atoms are located in penta-capped pentagonal prisms.


2012 ◽  
Vol 67 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Michael Johnscher ◽  
Rainer Pöttgen

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.


1996 ◽  
Vol 51 (6) ◽  
pp. 806-810 ◽  
Author(s):  
Rainer Pöttgen

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


2004 ◽  
Vol 59 (8) ◽  
pp. 943-946 ◽  
Author(s):  
Viktor Hlukhyy ◽  
Rainer Pöttgen

AbstractThe hexagonal Laves phase MgIr2 was synthesized from the elements in a sealed tantalum tube in an induction furnace. MgIr2 was investigated by powder and single crystal X-ray data: P63/mmc, a = 516.9(1), c = 838.5(2) pm, wR2 = 0.0771, 135 F2 values, and 11 variable parameters. The magnesium atoms have coordination number (CN) 16 (12 Ir + 4 Mg), while the smaller iridium atoms, Ir1 and Ir2, both have CN 12 (6 Ir + 6 Mg). The Ir-Ir distances within the three-dimensional network of face- and corner-sharing Ir4/2 tetrahedra range from 250 to 267 pm. The magnesium atoms have one shorter (306 pm) and three longer (319 pm) magnesium contacts. The crystal chemistry of MgIr2 is briefly discussed and compared with the other binary Mg-Ir intermetallics.


Science ◽  
2018 ◽  
Vol 361 (6397) ◽  
pp. 48-52 ◽  
Author(s):  
Tianqiong Ma ◽  
Eugene A. Kapustin ◽  
Shawn X. Yin ◽  
Lin Liang ◽  
Zhengyang Zhou ◽  
...  

The crystallization problem is an outstanding challenge in the chemistry of porous covalent organic frameworks (COFs). Their structural characterization has been limited to modeling and solutions based on powder x-ray or electron diffraction data. Single crystals of COFs amenable to x-ray diffraction characterization have not been reported. Here, we developed a general procedure to grow large single crystals of three-dimensional imine-based COFs (COF-300, hydrated form of COF-300, COF-303, LZU-79, and LZU-111). The high quality of the crystals allowed collection of single-crystal x-ray diffraction data of up to 0.83-angstrom resolution, leading to unambiguous solution and precise anisotropic refinement. Characteristics such as degree of interpenetration, arrangement of water guests, the reversed imine connectivity, linker disorder, and uncommon topology were deciphered with atomic precision—aspects impossible to determine without single crystals.


2017 ◽  
Vol 72 (11) ◽  
pp. 775-780
Author(s):  
Daniel Voßwinkel ◽  
Rainer Pöttgen

AbstractPolycrystalline RERh6Si4 (RE=La, Nd, Tb, Dy, Er, Yb) samples can be synthesized by arc-melting of the elements. Single crystals of LaRh6Si4, NdRh6Si4 and YbRh6Si4 were synthesized from the elements in bismuth fluxes (non-reactive flux medium). The structures were refined on the basis of single-crystal X-ray diffractometer data: LiCo6P4 type, P6̅m2, a=700.56(3), c=380.55(1) pm, wR2=0.0257, 317 F2 values, 19 variables for LaRh6Si4, a=698.4(5), c=377.7(2) pm, wR2=0.0578, 219 F2 values, 19 variables for NdRh6Si4 and a=696.00(3), c=371.97(1) pm, wR2=0.0440, 309 F2 values, 19 variables for YbRh6Si4. The rhodium and silicon atoms build up three-dimensional, covalently bonded [Rh6Si4]δ− polyanionic networks with Rh–Si distances ranging from 239 to 249 pm. The rare earth atoms fill larger cavities within channels of these networks and they are coordinated by six silicon and twelve rhodium atoms in the form of hexa-capped hexagonal prisms.


2013 ◽  
Vol 68 (11) ◽  
pp. 1185-1190 ◽  
Author(s):  
Ulrike Pfannenschmidt ◽  
Rainer Pöttgen

Single crystals of the new arsenide Eu4Ir8As7 were grown from a lead flux. The structure was refined on the basis of single-crystal X-ray diffractometer data: Ca4Ir8P7 type, P21=m, a=1311.3(1), b = 408:4(1), c = 1360:3(1) pm, β = 98:45(1)°, wR2=0.0640, 1985 F2 values, 95 variables. The iridium and arsenic atoms in the Eu4Ir8As7 structure build up a complex three-dimensional, covalently bonded [Ir8As7] network with Ir-As distances ranging from 239 to 260 pm. Each iridium atom has three or four arsenic neighbors in slightly distorted trigonal-planar or tetrahedral coordination. The four crystallographically independent europium atoms fill cavities of coordination numbers 12, 13, and 15 (2) within the [Ir8As7] network. Parts of the Eu4Ir8As7 structure resemble known simpler structure types, and one can describe the Eu4Ir8As7 structure as an intergrowth variant of CaBe2Ge2-, TiNiSi- and AlB2-related slabs.


2007 ◽  
Vol 62 (4) ◽  
pp. 610-612 ◽  
Author(s):  
Ahmet Doğan ◽  
Ute Ch. Rodewald ◽  
Rainer Pöttgen

The intermetallic cadmium compounds LaPdCd2 and PrNi0.951(4)Cd2 were synthesized from the elements in sealed tantalum tubes in an induction furnace. Both phases were investigated by X-ray diffraction on powders and single crystals: MgCuAl2-type, Cmcm, Z = 4, a = 431.9(1), b = 1015.7(4), c = 835.7(2) pm, wR2 = 0.0436, 326 F2 values, 16 variables for LaPdCd2 and a = 420.26(8), b = 981.0(2), c = 815.3(1) pm, wR2 = 0.0404, 604 F2 values, 17 variables for PrNi0.951(4)Cd2. A small nickel deficit was observed for the PrNi0.951(4)Cd2 crystal. The cadmium atoms build up orthorhombically distorted three-dimensional networks (Cd-Cd distances: 302 - 334 pm) that resemble the structure of hexagonal diamond, lonsdaleite. Together with the palladium (nickel) atoms, [PdCd2] and [Ni0.951(4)Cd2] networks are formed which leave distorted hexagonal channels for the rare earth atoms.


1999 ◽  
Vol 54 (7) ◽  
pp. 870-876 ◽  
Author(s):  
Bernd Ziegler ◽  
Michael Witzel ◽  
Martin Schwarten ◽  
Dietrich Babel

The results of a Rietveld refinement of CsMnCr(CN)6 · D2O neutron powder data (a = 1084.3(1) pm, F4̄3m, Z = 4) and of a neutron single crystal structure refinement of tetragonal NMe4MnII(Cr0,06Mn0,94)III(CN)6 · 8 H2O (a = 1065.8(21), c = 1064.6(26) pm, P4/n, Z = 2) at ambient temperature are reported. Single crystal X-ray analyses of the isostructural octahydrate NMe4MnCo(CN)6 · 8 H20 (a = 1062.1 (1), c = 1046.2( 1) pm) and of gel-grown crystals of cubic Mn3II[MnIII(CN)6]2 - 15 H2O (a = 1062.6(3) pm, Fm3̄m, Z = 4/3) and Cd3[Fe(CN)6]2 · 15 H2O (a = 1067.7(3) pm) were performed as well. The latter “Prussian Blues” are highly disordered and intermediate with respect to cyano-bridging between the above three-dimensional cesium and one-dimensional tetramethylammonium compounds.


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