Osmium and magnesium: structural segregation in the rare earth-rich intermetallics RE4OsMg (RE=La–Nd, Sm) and RE9TMg4 (RE=Gd, Tb)

2019 ◽  
Vol 74 (6) ◽  
pp. 519-525 ◽  
Author(s):  
Theresa Block ◽  
Sebastian Stein ◽  
Lukas Heletta ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Powder Diffraction ◽  
Rare Earth Metal ◽  
Rare Earth Metals ◽  
Three Dimensional ◽  
Earth Metal ◽  
Intermetallic Phases ◽  
Induction Melting ◽  
X Ray ◽  
Dimensional Network

AbstractTernary rare earth metal-rich intermetallic phases containing osmium and magnesium were obtained by induction melting of the elements in sealed niobium ampoules under argon followed by annealing in muffle furnaces. The large rare earth elements form the series of Gd4RhIn-type (F4̅3m) intermetallicsRE4OsMg withRE = La–Nd and Sm, while the smaller rare earth metals gadolinium and terbium form the Y9CoMg4-type (P63/mmc) phases Gd9OsMg4and Tb9OsMg4. All samples were characterized by X-ray powder diffraction (Guinier technique). The structures of Ce4Os0.973Mg1.027(a = 1406.54(7) pm,wR2 = 0.0478), Nd4Os0.978Mg1.022(a = 1402.00(7) pm,wR2 = 0.0463), Sm4Os0.920Mg1.080(a = 1387.33(5) pm,wR2 = 0.0378) and Gd9OsMg4(a = 971.01(5),c = 980.43(5) pm,wR2 = 0.0494) were refined from single-crystal X-ray diffractometer data. The threeRE4OsMg phases show small degrees of Os/Mg mixing, as is frequently observed for Rh/In in Gd4RhIn-type intermetallics. The basic building units in both structures are osmium-centeredRE6trigonal prisms that are condensed with emptyRE6octahedra. The magnesium atoms in both types build Mg4tetrahedra. The latter are isolated (312 pm Mg–Mg in Ce4OsMg) and incorporated within the three-dimensional network of prisms and octahedra in theRE4OsMg phases while one observes rows of corner- and face-sharing tetrahedra in Gd9OsMg4(305 and 314 pm Mg–Mg). In both structure types direct Os–Mg bonding is not observed.

scholarly journals Zinc-lead ordering in equiatomic rare earth plumbides REZnPb (RE=La–Nd and Sm–Tb)

2019 ◽  
Vol 74 (2) ◽  
pp. 227-232
Author(s):  
Lukas Heletta ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Powder Diffraction ◽  
Valence Electron ◽  
Rare Earth Metals ◽  
Three Dimensional ◽  
Induction Melting ◽  
Stacking Sequence ◽  
Crystal Chemical ◽  
Zintl Phase ◽  
X Ray

AbstractThe plumbides REZnPb (RE=rare earth metals La–Nd and Sm–Tb) were synthesized by induction melting of the elements in sealed niobium ampoules. The samples were characterized by X-ray powder diffraction. The structures of the praseodymium and neodymium compound were refined from single-crystal X-ray diffractometer data: YPtAs type, P63/mmc, a=461.32(8), c=1658.00(3) pm, wR2=0.0588, 267 F2 values, 12 variables for PrZnPb and a=460.12(3), c=1642.7(1), wR2=0.0617, 243 F2 values, 12 variables for NdZnPb. The plumbides with RE=La, Ce, Sm, Gd and Tb are isotypic while the Zintl phase EuZnPb crystallizes with the orthorhombic TiNiSi type, Pnma, a=796.6(2), b=482.53(9), c=822.9(2) pm. The zinc and lead atoms build up polyanionic networks: slightly puckered Zn3Pb3 layers in AA′BB′ stacking sequence in the YPtAs type plumbides and a three-dimensional [ZnPb]2− network with distorted tetrahedral ZnPb4/4 coordination in EuZnSn. The different crystal structures are a consequence of the valence electron count, i.e. 18 for EuZnSn and 19 for the hexagonal plumbides. The crystal chemical details and bonding peculiarities are discussed.

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.

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)

Rare Earth-rich Magnesium Compounds RE4RhMg (RE = Y, La–Nd, Sm, Gd–Tm, Lu)

2007 ◽  
Vol 62 (5) ◽  
pp. 642-646 ◽  
Author(s):  
Selcan Tuncel ◽  
Ute Ch. Rodewald ◽  
Bernard Chevalier ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
High Frequency ◽  
Three Dimensional ◽  
Earth Metal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensional Network ◽  
Magnesium Compounds ◽  
Rare Earth Coordination ◽  
Trigonal Prismatic

Abstract The series of magnesium compounds RE4RhMg (RE = Y, La-Nd, Sm, Gd-Tm, Lu) was prepared by high-frequency melting of the elements in sealed tantalum tubes. All samples were investigated by powder X-ray diffraction. The structures with RE = Sm, Gd, Dy, Ho, and Er as rare earth metal components were refined from single crystal diffractometer data: Gd4RhIn-type, F4̄3m, Z = 16, a = 1392.1(1) pm, wR2 = 0.060, 616 F2 values, 19 variables for Sm4RhMg, a = 1380.8(2) pm, wR2 = 0.071, 530 F2 values, 19 variables for Gd4RhMg, a = 1366.9(1) pm, wR2 = 0.070, 594 F2 values, 20 variables for Dy4RhMg, a = 1355.7(2) pm, wR2 = 0.077, 578 F2 values, 20 variables for Ho3.52RhMg1.48, and a = 1355.4(2) pm, wR2 = 0.075, 559 F2 values, 20 variables for Er3.94RhMg1.06 .The rhodium atoms have slightly distorted trigonal prismatic rare earth coordination. Condensation of the RhRE6 prisms leads to a three-dimensional network which leaves large voids that are filled by regular Mg4 tetrahedra with a Mg-Mg distance of 312 pm in Sm4RhMg. The magnesium atoms have twelve nearest neighbors (3 Mg + 9 RE) in icosahedral coordination. In the structures with holmium and erbium, the RE1 positions which are not involved in the trigonal prismatic network exhibit RE1/Mg mixing. Shortest distances occur for Sm-Rh (286 pm) within the rigid three-dimensional network of condensed trigonal prisms.

Rows of corner- and face-sharing Mg4 tetrahedra arranged as hexagonal rod packing in the hexagonal Laves phases REMg2 and the rare earth-rich phases RE9CoMg4 (RE=Y, Dy-Tm, Lu)

2018 ◽  
Vol 233 (9-10) ◽  
pp. 607-613 ◽  
Author(s):  
Sebastian Stein ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Diffraction Data ◽  
Earth Metal ◽  
Structural Motif ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Laves Phases ◽  
X Ray ◽  
The Many

Abstract Six new rare earth metal-rich intermetallic compounds RE9CoMg4 with RE=Y, Dy, Ho, Er, Tm and Lu were synthesized by induction-melting the elements in sealed niobium ampoules followed by annealing in muffle furnaces. The structures of Y9CoMg4 and Tm8.56CoMg4.44 were refined from single-crystal X-ray diffraction data: P63/mmc, a=965.65(6), c=971.07(5) pm, wR2=0.0599, 614 F2 values, 20 variables for Y9CoMg4 and a=945.20(4), c=953.11(5) pm, wR2=0.0358, 585 F2 values, 21 variables for Tm8.56CoMg4.44 (a small homogeneity range results from Tm/Mg mixing). The RE9CoMg4 phases crystallize with a coloring variant of the aristotype Co2Al5. The striking structural motif is a hexagonal rod packing of rows of corner- and face-sharing tetrahedral Mg4 clusters with Mg–Mg distances ranging from 304 to 317 pm in Y9CoMg4. These rows are similar to the hexagonal Laves phases REMg2. The space between the rows is filled with rows of face-sharing Co@Y6 trigonal prisms (TP) and empty Y6 octahedra (O) in the sequence –TP–O–O–. The many isopointal coloring variants of the aristotype Co2Al5 are briefly discussed.

Li3Ce5Ge4, ein neuer Typ eines ternären Germanids des Lithiums mit Selten-Erd-Metallen Li3Ce5Ge4, a New Type of Ternary Compound of Lithium with Rare Earth Metal and Germanium

1979 ◽  
Vol 34 (9) ◽  
pp. 1234-1236 ◽  
Author(s):  
Axel Czybulka ◽  
Hans-Uwe Schuster
Keyword(s):  
Rare Earth ◽  
Ternary Compound ◽  
Rare Earth Metal ◽  
Three Dimensional ◽  
Earth Metal ◽  
Space Group ◽  
Metal Atoms ◽  
Dimensional Network ◽  
New Type ◽  
Group B

Abstract The ternary compound Li3Ce5Ge4 has been prepared and structurally characterized. It crystallizes orthorhombically (a = 1885 pm, b = 694.7 pm, c = 447.6 pm, space group B 2 mm). The structure shows germanium chains in a three-dimensional network of metal atoms.

Synthese und Kristallstrukturen von Seltenerdmetall-Antimoniden des Palladiums / Synthesis and Crystal Structures of Antimonides of Rare-Earth Metals and Palladium

2006 ◽  
Vol 61 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Anette Imre ◽  
Albrecht Mewis
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Three Dimensional ◽  
Earth Metal ◽  
Type Structure ◽  
X Ray ◽  
Metal Atoms ◽  
New Compounds ◽  
Ray Methods ◽  
The Rare Earth

The new compounds Pr3Pd6Sb5 (a = 13.442(3), b = 4.442(1), c = 9.994(2) Å ), Nd3Pd6Sb5 (a = 13.412(3), b = 4.431(1), c = 9.962(2) Å), and Gd3Pd6Sb5 (a = 13.293(2), b = 4.397(1), c = 9.881(2) Å) are isotypic and crystallize with the Ce3Pd6Sb5 type structure (Pmmn; Z = 2). The rare-earth metal atoms are arranged in form of three pseudo-body-centered subcells, whereas Pd and Sb atoms form a three-dimensional arrangement derived from the well-known ThCr2Si2 and CaBe2Ge2 structures. GdPdSb (a = 4.566(1), c = 7.444(1) Å) and DyPdSb (a = 4.545(1), c = 7.354(1) Å) crystallize with an ordered variant of the CaIn2 type structure (P63mc; Z = 2), also called as LiGaGe type, with slightly puckered hexagon nets of Pd and Sb atoms, which trigonally coordinate each other. In this series a decreasing radius of the rare-earth metal allows a tetrahedral non-metal environment of the Pd atoms and accordingly ScPdSb (a = 6.310(1) Å) forms the MgAgAs type structure (F4̄3m; Z = 4), a filled variant of the sphalerite type. The antimonides were prepared by heating mixtures of the elements at 600 °C and subsequent annealing at 900 - 1100 °C. Their structures have been determined by single-crystal X-ray methods.

X-Ray Diffraction Study of Rare Earth Epitaxial Structures Grown by MBE onto (111) GaAs

1989 ◽  
Vol 151 ◽  
Author(s):  
W. R. Bennett ◽  
R. F. C. Farrow ◽  
S. S. P. Parkin ◽  
E. E. Marinero
Keyword(s):  
Rare Earth ◽  
Molecular Beam Epitaxy ◽  
Rare Earth Metal ◽  
Molecular Beam ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Metal Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Components

ABSTRACTWe report on the new epitaxial system LaF3/Er/Dy/Er/LaF3/GaAs (111) grown by molecular beam epitaxy. X-ray diffraction studies have been used to determine the epitaxial relationships between the rare earths, the LaF3 and the substrate. Further studies of symmetric and asymmetric reflections yielded the in-plane and perpendicular strain components of the rare earth layers. Such systems may be used to probe the effects of magnetoelastic interactions and dimensionality on magnetic ordering in rare earth metal films and multilayers.

Ternary aurides RE4Mg3Au10 (RE=Y, Nd, Sm, Gd–Dy) and their silver analogues

2015 ◽  
Vol 70 (2) ◽  
pp. 135-141 ◽  
Author(s):  
Theresa Block ◽  
Michael Johnscher ◽  
Stefan Linsinger ◽  
Ute Ch. Rodewald ◽  
Rainer Pöttgen
Keyword(s):  
Three Dimensional ◽  
Intermetallic Phases ◽  
Point Of View ◽  
Site Preference ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Coordination Numbers ◽  
Cation Sites

AbstractThe ternary aurides RE4Mg3Au10 (RE=Y, Nd, Sm, Gd–Dy) and their silver analogues were synthesized by induction melting of the elements in sealed niobium tubes. These intermetallic phases were characterized by powder X-ray diffraction. They crystallize with the Ca4In3Au10-type structure, which, from a geometrical point of view, is a ternary ordered version of Zr7Ni10 with the rare earth and magnesium atoms ordering on the four crystallographically independent zirconium sites. The structures of crystals from three differently prepared gadolinium samples were refined from single-crystal X-ray diffractometer data: Cmca, a=1366.69(3), b=998.07(4), c=1005.54(3) pm, wR2=0.0332, 1234 F2 values, 46 variables for Gd4.43Mg2.57Au10, a=1378.7(1), b=1005.3(1), c=1011.2(1) pm, wR2=0.0409, 1255 F2 values, 48 variables for Gd5.50Mg1.50Au10, and a=1350.2(5), b=995.5(1), c=1009.3(1) pm, wR2=0.0478, 1075 F2 values, 48 variables for Gd5.61Mg1.39Au10. All crystals show substantial Mg/Gd mixing on two sites. The gold atoms form a pronounced two-dimensional substructure with Au–Au distances of 278 to 297 pm in Gd4.43Mg2.57Au10. These gold blocks are condensed via magnesium atoms (278–315 pm Mg–Au). The gadolinium atoms fill larger cavities within the three-dimensional networks. The magnesium vs. gadolinium site preference is a consequence of the different coordination numbers of the cation sites. All phases show homogeneity ranges RE4+xMg3–xAg10 and RE4+xMg3–xAu10. The influence of the synthesis conditions is briefly discussed.

Crystal structure of (Z)-cefprozil monohydrate, C18H19N3O5S(H2O)

2019 ◽  
Vol 34 (4) ◽  
pp. 379-388
Author(s):  
Zachary R. Butler ◽  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Density Functional ◽  
Three Dimensional ◽  
Ion Pair ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
X Ray ◽  
Dimensional Network ◽  
Acid Proton

The crystal structure of cefprozil monohydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Cefprozil monohydrate crystallizes in space group P21 (#4) with a = 11.26513(6), b = 11.34004(5), c = 14.72649(11) Å, β = 90.1250(4)°, V = 1881.262(15) Å3, and Z = 4. Although a reasonable fit was obtained using an orthorhombic model, closer examination showed that many peaks were split and/or had shoulders, and thus the true symmetry was monoclinic. DFT calculations revealed that one carboxylic acid proton moved to an amino group. The structure thus contains one ion pair and one pair of neutral molecules. This protonation was confirmed by infrared spectroscopy. There is an extensive array of hydrogen bonds resulting in a three-dimensional network. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™.

Sign in / Sign up

Export Citation Format

Share Document