Birgit Heying

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

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. Graphical Abstract 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

Structure and Magnetic Properties of GdPt2In and GdPt2Sn

The platinum-rich intermetallic compounds GdPt2In and GdPt2Sn were synthesized by arc-melting of the elements and subsequent annealing. The structures were refined from single crystal X-ray diffractometer data: ZrPt2Al type, space group P63/mmc, a = 455.1(1), c = 899.3(3) pm, wR2 = 0.0361, 166 F2 values, 9 variables for GdPt2In, and a = 453.2(1), c = 906.5(2) pm, wR2 = 0.0915, 166 F2 values, 9 variables for GdPt2Sn. The platinum and indium (tin) atoms build up threedimensional [Pt2In] and [Pt2Sn] networks with short Pt-In (Pt-Sn) distances and Pt2 dumb-bells (290 and 297 pm in GdPt2In and GdPt2Sn). The gadolinium atoms have coordination number 14 with 8 Pt and 6 In (Sn) neighbors. Magnetic susceptibility measurements on GdPt2In show Curie-Weiss behavior with an experimental magnetic moment of 8.06(2) μB/Gd atom. GdPt2In orders ferromagnetically at 27.7(2) K Graphical Abstract Structure and Magnetic Properties of GdPt2In and GdPt2Sn

Rare Earth Site Preference in the Doped Laser Host Material Sc2SiO5. A Single-Crystal X-Ray Study

Single crystals of the laser host material Sc2SiO5 as well as thulium- (4 at.-%) and ytterbium- (5 at.-%) doped samples were prepared by the Czochralski technique. The structures of Sc2SiO5, Tm3+:Sc2SiO5, and Yb3+:Sc2SiO5 were refined on the basis of high-quality single-crystal X-ray diffraction data: monoclinic Y2SiO5 type, space group C2/c. The X-ray data unambiguously show that the larger rare earth cations exclusively occupy the 8 f site with oxygen coordination number 7. Graphical Abstract Rare Earth Site Preference in the Doped Laser Host Material Sc2SiO5. A Single-Crystal X-Ray Study

First Refinement of the Sinoite Structure of a Natural Crystal from the Neuschwanstein (EL6) Meteorite

A well-shaped sinoite crystal was milled out of a polished thin section of the Neuschwanstein (EL6) chondrite. The structure was refined on the basis of X-ray single crystal data:Cmc21, a=885.66(18), b = 549.61(11), c = 484.23(10) pm, R1 = 0.0282, 491 F2 values, 26 variable parameters. The structure consists of a complex three-dimensional network of corner-sharing SiN3O tetrahedra (Si-O 161.9, Si-N 171.9-172.8 pm). The crystal chemical peculiarities of Si2N2O are briefly discussed.

Polymorphism in the Germanides REPdGe with the Heavy Rare Earth Elements

The structures of the equiatomic germanides REPdGe with the heavy rare earth elements have been reinvestigated with respect to palladium-germanium ordering. The samples were prepared by arc-melting of the elements followed by annealing procedures in sealed silica ampoules at different temperatures. The structures of YPdGe, HT-TbPdGe, LT-DyPdGe, HT-DyPdGe, LT-HoPdGe, HT-HoPdGe, ErPdGe, and TmPdGe, and of the new germanide LuPdGe, were refined from single crystal diffractometer data. LT-DyPdGe and LT-HoPdGe crystallize with the YPdSi-type structure, space group Pmmn. The other germanides crystallize with the non-centrosymmetric YbAuSn structure, space group Imm2. All structures are orthorhombically-distorted superstructure variants of AlB2, and they show strong intralayer Pd-Ge bonding within the ordered Pd3Ge3 hexagons. There is weak Pd-Ge and Pd-Pd interlayer bonding. The crystal chemical relationship between the different superstructures is discussed. Graphical Abstract Polymorphism in the Germanides REPdGe with the Heavy Rare Earth Elements

Platinum-Germanium Ordering in the Germanides REPtGe with the Heavy Rare Earth Elements

The equiatomic germanides REPtGe with the heavy rare earth elements (RE) have been reinvestigated with respect to platinum-germanium ordering. The compounds were prepared by arc-melting of the elements followed by annealing for two weeks at 1070 K. The REPtGe germanides crystallize with the TiNiSi-type structure, space group Pnma. The structures of ErPtGe (a = 692.01(5), b = 432.03(4), c = 753.19(5) pm, wR2 = 0.0523, 435 F2, 20 variables) and the new germanide LuPtGe (a = 683.1(1), b = 429.2(1), c = 750.3(1) pm, wR2 = 0.0696, 358 F2, 20 variables) have been refined from single crystal diffractometer data. These structures exhibit three-dimensional [PtGe] networks with strong Pt-Ge intra- (251 - 255 pm in LuPtGe) and weaker interlayer (272 pm in LuPtGe) interactions. The crystal chemical peculiarities of the whole REPtGe series are briefly discussed. Graphical Abstract Platinum-Germanium Ordering in the Germanides REPtGe with the Heavy Rare Earth Elements

The high-pressure phase of CePtAl

Abstract The intermetallic aluminum compound HP-CePtAl was synthesized by arc melting of the elements with subsequent high-pressure/high-temperature treatment at 1620 K and 10.5 GPa in a multianvil press. The compound crystallizes in the hexagonal MgZn2-type structure (P63/mmc) with lattice parameters of a=552.7(1) and c=898.8(2) pm refined from powder X-ray diffraction data. With the help of single crystal investigations (wR=0.0527, 187 F2 values, 13 variables), the proposed structure type was confirmed and the mixed Pt/Al site occupations could be refined. Magnetic susceptibility measurements showed a disappearance of the complex magnetic ordering phenomena, which are observed in NP-CePtAl.

The germanides Er5Pd4Ge8 and Tm5Pd4Ge8 – 3D [Pd4Ge8] polyanions with Ge2 dumb-bells and Ge4 chains in cis-conformation

Abstract Tm5Pd4Ge8 was synthesized by melting of the elements in an arc-melting furnace. The new germanide was characterized by powder and single-crystal X-ray diffraction: own structure type, P21/m, a=574.3(1), b=1380.4(3), c=836.4(1) pm, β=107.57(2)°, V=0.6321 nm3, wR2=0.0578, 2533 F2 values, 86 variables. The palladium and germanium atoms built up a three-dimensional [Pd4Ge8]15− polyanionic network which contains a unique germanium substructure composed of the Zintl anions Ge26− dumb-bells and Ge410− chains in cis-conformation. The palladium atoms within the network have distorted square pyramidal germanium coordination. The three crystallographically independent thulium atoms have coordination numbers 15, 16 and 17 with partial motifs of the Frank-Kasper type polyhedra. The isotypic germanide Er5Pd4Ge8 forms only after annealing the arc-melted sample at 1070 K for 1 week: a=575.14(9), b=1386.3(3), c=838.4(1) pm, β=107.51(2)°, V=0.6375 nm3.

Indides RE3T2In4 (RE = Y, Gd–Tm, Lu; T = Ni, Ru, Rh) with a ZrNiAl superstructure

Abstract Three series of rare earth-transition metal-indides RE3T2In4 (RE=Y, Gd–Tm, Lu; T=Ni, Ru, Rh) were synthesized from arc-melted RE3T2 precursor compounds and indium tear shot in sealed niobium ampoules using different annealing sequences. The new indides crystallize with the hexagonal Lu3Co2In4-type structure, space group P6̅. All samples were characterized on the basis of Guinier powder patterns and six structures were refined from single crystal X-ray diffractometer data. The RE3T2In4 structures are derived from the ZrNiAl type through RE/In ordering, paralleled by a symmetry reduction from P6̅2m to P6̅. This induces twinning for some of the investigated crystals. The main crystal chemical motifs of the RE3T2In4 structures are trigonal prisms of rare earth, respectively indium atoms that are filled by the transition metals.

The Stannides Sm6Pd10–xSn11 and Sm3Pd5–x

Abstract The stannides Sm6Pd10–xSn11 and Sm3Pd5–xSn5 were synthesized from the elements by arc-melting. They were studied by powder and single-crystal X-ray data: C2/m, a  =  1720.45(10), b  =  451.97(2), c  =  1420.60(8), β  =  99.705(5)°, wR2  =  0.086, 2076 F2 values, 83 variables for Sm3Pd4.95(1)Sn5 and C2/m, a  =  1738.68(7), b  =  451.49(1), c  =  1692.68(7), β  =  121.375(3)°, wR2  =  0.0335, 2164 F2 values, 85 variables for Sm6Pd9.82(1)Sn11. Both structures show small defects for one palladium site. The palladium and tin atoms in Sm6Pd10–xSn11 and Sm3Pd5–xSn5 build up complex three-dimensional polyanionic networks in which the samarium atoms fill cavities within distorted pentagonal channels. In addition to strong covalent Pd–Sn bonding, the polyanions are further stabilized by Pd–Pd and Sn–Sn bonding.