Rhodium-rich silicides RERh6Si4 (RE=La, Nd, Tb, Dy, Er, Yb)

2017 ◽  
Vol 72 (11) ◽  
pp. 775-780
Author(s):  
Daniel Voßwinkel ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Single Crystals ◽  
Three Dimensional ◽  
X Ray ◽  
Arc Melting ◽  
Covalently Bonded ◽  
Reactive Flux ◽  
The Rare Earth

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.

Single-crystal Data of Ternary Germanides RE2Nb3Ge4 (RE = Sc, Y, Gd–Er, Lu) and Sc2Ta3Ge4 with Ordered Sm5Ge4-type Structure

2013 ◽  
Vol 68 (5-6) ◽  
pp. 625-634 ◽  
Author(s):  
Bastian Reker ◽  
Samir F. Matar ◽  
Ute Ch. Rodewald ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Coordination Number ◽  
Electronic Structure Calculations ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Structure Calculations ◽  
The Rare Earth

Small single crystals of the Sm5Ge4-type (space group Pnma) germanides RE2Nb3Ge4 (RE = Sc, Y, Gd-Er, Lu) and Sc2Ta3Ge4 were synthesized by arc-melting of the respective elements. The samples were characterized by powder and single-crystal X-ray diffraction. In all structures, except for Sc2.04Nb2.96Ge4 and Sc2.19Ta2.81Ge4, the rare earth and niobium atoms show full ordering on the three crystallographically independent samarium sites of the Sm5Ge4 type. Two sites with coordination number 6 are occupied by niobium, while the slightly larger site with coordination number 7 is filled with the rare earth element. Small homogeneity ranges with RE=Nb and RE=Ta mixing can be expected for all compounds. The ordered substitution of two rare earth sites by niobium or tantalum has drastic effects on the coordination number and chemical bonding. This was studied for the pair Y5Ge4/Y2Nb3Ge4. Electronic structure calculations show larger charge transfer from yttrium to germanium for Y5Ge4, contrary to Y2Nb3Ge4 which shows stronger covalent bonding due to the presence of Nb replacing Y at two sites

On the Solid Solutions Eu1–xPt2Inx, Gd1–xPt2Inx, and Tm1–xNi2Inx

2005 ◽  
Vol 60 (4) ◽  
pp. 393-397 ◽  
Author(s):  
Mar’yana Lukachuk ◽  
Yaroslav M. Kalychak ◽  
Tom Nilges ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Coordination Number ◽  
Solid Solutions ◽  
Three Dimensional ◽  
Induction Melting ◽  
Single Crystal Diffraction ◽  
Laves Phases ◽  
X Ray ◽  
Arc Melting

The binary cubic Laves phases EuPt2, GdPt2, and TmNi2 form extended solid solutions Eu1−xPt2Inx, Gd1−xPt2Inx, and Tm1−xNi2Inx. Samples within these homogeneity ranges have been prepared from the elements by arc-melting on water-cooled copper chills or by induction melting in sealed tantalum tubes and subsequent annealing. The indides were characterized by X-ray powder and single crystal diffraction: MgCu2 type, Fd3̅m, a = 770.68(6) pm, wR2 = 0.0251, 67 F2 values, 6 variables for Eu0.94(3)Pt2In0.06(3), a = 769.16(6) pm, wR2 = 0.0244, 67 F2 values, 6 variables for Eu0.85(2)Pt2In0.15(2), a = 760.12(9) pm, wR2 = 0.0693, 65 F2 values, 6 variables for Gd0.79(5)Pt2In0.21(5), and MgCu4Sn type, F 4̅3m, a=700.27(6) pm, wR2=0.0368, BASF=0.13(2), 175 F2 values, 8 variables for TmNi4In. The platinum and nickel atoms build up three-dimensional networks of corner-sharing Pt4/2 and Ni4/2 tetrahedra. These networks leave larger voids of coordination number 16 that are filled with the rare earth (RE) and the indium atoms. While the thulium and indium atoms are ordered in TmNi4In, one observes mixed RE/In occupancies in Eu0.94(3)Pt2In0.06(3), Eu0.85(2)Pt2In0.15(2), and Gd0.79(5)Pt2In0.21(5)

The Stannides RERhSn (RE = Ho - Yb) and ScTSn (T = Pd, Pt) - Structure Refinements and 119Sn Mössbauer Spectroscopy

2001 ◽  
Vol 56 (7) ◽  
pp. 589-597 ◽  
Author(s):  
Ratikanta Mishra ◽  
Rainer Pöttgen ◽  
Rolf-Dieter Hoffmann ◽  
Henning Trill ◽  
Bernd D. Mosel ◽  
...  
Keyword(s):  
Rare Earth ◽  
Transition Metal ◽  
Three Dimensional ◽  
Lattice Parameter ◽  
Interatomic Distances ◽  
Space Group ◽  
X Ray ◽  
Arc Melting ◽  
Rhodium Stannides ◽  
The Rare Earth

Abstract The stannides RERhSn (RE = Ho -Yb) and ScTSn (T = Pd, Pt) were prepared by reaction of the elements in sealed tantalum tubes in a high-frequency furnace, by arc-melting, or by a tin-flux technique in quartz tubes. The rhodium based stannides crystallize with the ZrNiAl type structure, space group P6̄2m. The four structures were refined from single crystal X-ray data: a = 754.5(3), c = 377.1(1) pm, wR2 = 0.0357, 233 F2 values for HoRhSn, a = 753.3(1), c = 372.16(8) pm, wR2 = 0.0721, 233 F2 values for ErRhSn, a = 753.7(3), c = 369.0(2) pm, wR2 = 0.0671,233 F2 values for TmRhSn, and a = 753.17(5), c = 366.53(4) pm, wR2 = 0.0566, 180 F2 values for YbRhSn with 14 parameters for each refinement. ScPdSn and ScPtSn adopt the HfRhSn type, a superstructure of ZrNiAl, space group P6̄2c: a = 747.5(1), c = 710.2(1) pm, for ScPdSn, and a = 738.37(9), c = 729.47(9) pm, wR2 = 0.0452,369 F2 values, 18 variables for ScPtSn. Structural motifs in these stannides are transition metal centered trigonal prisms formed by the rare earth and tin atoms. While these prisms are regular in the rhodium based stannides, significant distortions occur in ScPdSn and ScPtSn. The formation of the superstructure can be ascribed to packing reasons. The shortest interatomic distances occur between the transition metal (T) and tin atoms. These atoms form three-dimensional [FSn] networks in which the rare earth atoms fill distorted hexagonal channels. The series RERhSn displays a somewhat unique behavior. The a lattice parameter is more or less independent of the rare earth element, while the c lattice parameter shows the expected lanthanoid contraction. 119Sn Mössbauer spectroscopic data of the rhodium stannides show signals at isomer shifts varying from 1.77 to 1.82 mm/s subject to quadrupole splitting between 0.75 to 0.82 mm/s.

Lead-flux Growth of Eu4Ir8As7 Crystals

2013 ◽  
Vol 68 (11) ◽  
pp. 1185-1190 ◽  
Author(s):  
Ulrike Pfannenschmidt ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Three Dimensional ◽  
Flux Growth ◽  
Tetrahedral Coordination ◽  
X Ray ◽  
Coordination Numbers ◽  
Covalently Bonded ◽  
The Eu

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.

The Stannides RE2Ni2Sn (RE = Pr, Ho, Er, Tm) – Structural Transition from the W2B2Co to the Mo2B2Fe Type as a Function of the Rare Earth Size

2013 ◽  
Vol 68 (1) ◽  
pp. 10-16 ◽  
Author(s):  
Birgit Heying ◽  
Ute Ch. Rodewald ◽  
Bernard Chevalier
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Single Crystal ◽  
Earth Element ◽  
Structural Transition ◽  
Structure Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
The Rare Earth

The stannides RE2Ni2Sn (RE=Pr, Ho, Er, Tm) were synthesized by arc-melting of the elements and characterized by powder X-ray diffraction. Pr2Ni2Sn crystallizes with the orthorhombic W2B2Co-type structure, Immm, a=443.8(1), b=572.1(1), c=855.1(2) pm, wR2=0.0693, 293 F2 values, 13 variables. A structural transition to the tetragonal Mo2B2Fe type occurs for the heavier rare earth elements. The structures of Ho2Ni2Sn (a=729.26(9), c=366.66(7) pm, wR2=0.0504, 250 F2 values, 12 variables), Er2Ni2Sn (a=727.2(2), c=364.3(1) pm, wR2=0.0397, 262 F2 values, 12 variables), and Tm2Ni2Sn (a=725.2(1), c=362.8(1) pm, wR2=0.0545, 258 F2 values, 12 variables) were refined from single-crystal diffractometer data. The switch in structure type is driven by the size of the rare earth element. The [Ni2Sn] substructures are composed of Ni2Sn2 squares and Ni4Sn2 hexagons in Pr2Ni2Sn, and of Ni3Sn2 pentagons in Er2Ni2Sn. The Ni4Sn2 hexagons and Ni3Sn2 pentagons exhibit Ni2 pairs with Ni-Ni distances of 247 pm in Pr2Ni2Sn, and of 250 pm in Er2Ni2Sn.

Solid State Syntheses and Structure of LaPdCd2 and PrNi0.951(4)Cd2

2007 ◽  
Vol 62 (4) ◽  
pp. 610-612 ◽  
Author(s):  
Ahmet Doğan ◽  
Ute Ch. Rodewald ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Solid State ◽  
Single Crystals ◽  
Induction Furnace ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cadmium Compounds ◽  
Hexagonal Diamond ◽  
The Rare Earth

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.

Cd4 Tetrahedra and Condensed RE6Rh Trigonal Prisms as Building Units in the Rare Earth-rich Compounds RE15Rh5Cd2 (RE = La, Ce, Pr, Nd)

2011 ◽  
Vol 66 (6) ◽  
pp. 559-564 ◽  
Author(s):  
Frank Tappe ◽  
Ute Ch. Rodewald ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Three Dimensional ◽  
Induction Melting ◽  
X Ray ◽  
Dimensional Network ◽  
New Type ◽  
The Rare Earth ◽  
Trigonal Prisms

The rare earth-rich compounds RE15Rh5Cd2 (RE = La, Ce, Pr, Nd) were synthesized by induction melting of the elements in sealed tantalum tubes and characterized by X-ray powder diffraction. The structure of La15Rh5Cd2 was refined from single-crystal diffractometer data: new type, R3m, a = 1016.4(2), c = 4418.7(9) pm, wR2 = 0.0417, 2258 F2, 95 variables. Striking structural motifs in the RE15Rh5Cd2 intermetallics are rhodium-centered trigonal prisms RE6Rh which are condensed via common corners and edges to a complex three-dimensional network which leaves cavities for Cd4 tetrahedra and RE6 octahedra. The structural relationship with the recently discovered structure types Gd4RhIn and Pr23Ir7Mg4 is discussed.

SrPdGa3 type gallides RERhGa3 with RE=La, Ce and Pr

2020 ◽  
Vol 235 (3) ◽  
pp. 53-57
Author(s):  
Stefan Seidel ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Subsequent Annealing ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Muffle Furnace ◽  
X Ray ◽  
Arc Melting

AbstractThe ternary rare earth gallides RERhGa3 with RE = La, Ce and Pr were synthesized by arc-melting and subsequent annealing in a muffle furnace. The gallides were characterized through Guinier powder patterns and the structure of LaRhGa3 was refined from single-crystal X-ray diffraction data: SrPdGa3 type, Cmcm, a = 639.2(2), b = 1030.9(2), c = 589.3(2) pm, wR2 = 0.0964, 416 F2 values and 19 variables. The rhodium and gallium atoms build up a three-dimensional polyanionic network [RhGa3] which is stabilized through Rh–Ga (245–251 pm) and Ga–Ga (267–295 pm) bonds and filled by the lanthanum atoms. The crystal chemical relationship with the structures of LaRh2Ge2 (ThCr2Si2 type), LaRh2Ga2 (CaBe2Ge2 type) and LaRhGe3 (BaNiSn3 type) is discussed.

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.

Ternary Thallides REMgTl (Re = Y, La – Nd, Sm, Gd – Tm, Lu)

2005 ◽  
Vol 60 (3) ◽  
pp. 265-270 ◽  
Author(s):  
Rainer Kraft ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Rare Earth Metal ◽  
High Frequency ◽  
Three Dimensional ◽  
Earth Metal ◽  
X Ray ◽  
Sample Chamber ◽  
Trigonal Prismatic Coordination ◽  
Trigonal Prismatic

The rare earth metal (RE)-magnesium-thallides REMgTl (RE = Y, La-Nd, Sm, Gd-Tm, Lu) were prepared from the elements in sealed tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. The thallides were characterized through their X-ray powder patterns. They crystallize with the hexagonal ZrNiAl type structure, space group P62m, with three formula units per cell. Four structures were refined from X-ray single crystal diffractometer data: α = 750.5(1), c = 459.85(8) pm, wR2 = 0.0491, 364 F2 values, 14 variables for YMgTl; α = 781.3(1), c = 477.84(8) pm, wR2 = 0.0640, BASF = 0.09(2), 425 F2 values, 15 variables for LaMgTl; α = 774.1(1), c = 473.75(7) pm, wR2 = 0.0405, 295 F2 values, 14 variables for CeMgTl; a = 760.3(1), c = 465.93(8) pm, wR2 = 0.0262, 287 F2 values, 14 variables for SmMgTl. The PrMgTl, NdMgTl, GdMgTl, TbMgTl, and DyMgTl structures have been analyzed using the Rietveld technique. The REMgTl structures contain two cystallographically independent thallium sites, both with tri-capped trigonal prismatic coordination: Tl1Mg3RE6 and Tl2Mg6RE3. Together the magnesium and thallium atoms form three-dimensional [MgTl] networks with Mg-Mg distances of 327 and Mg-Tl distances in the range 299 - 303 pm (data for CeMgTl)

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