Synthesis, Structure, and Magnetic Properties of EuAgCd and YbAgCd

2001 ◽  
Vol 56 (7) ◽  
pp. 598-603 ◽  
Author(s):  
◽  
Gunter Kotzyba ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen

Abstract New intermetallic compounds EuAgCd and YbAgCd were synthesized in quantitative yield by reaction of the elements in sealed tantalum tubes in a high-frequency furnace. Both com­ pounds were investigated by X-ray diffraction on powders and single crystals: KHg2 type, Imma, a = 490.41(8), b = 771.0(1), c = 834.4(2) pm, wR2 = 0.0624, 255 F2 values, 12 variables for EuAgCd, and MgZn2 type, Pb3/mmc, a = 584.66(5), c = 946.83(9) pm, wR2 = 0.0502, 187 F2 values, 11 variables for YbAgCd. Owing to the very small difference in scattering power, no long range ordering of the silver and cadmium atoms is evident from the X-ray data, although Ag-Cd ordering is expected. The silver and cadmium atoms randomly occupy the mercury and zinc positions of the KHg2 and MgZn2 type structures, respectively. In EuAgCd the [AgCd] substructure consists of strongly puckered, orthorhombically distorted Ag3 Cd3 hexagons, while a three-dimensional network of face-and comer-sharing tetrahedra is observed in YbAgCd. The rare earth atoms fill the space between the Ag3 Cd3 hexagons (EuAgCd) or within the three-dimensional tetrahedral network (YbAgCd). Magnetic susceptibility measurements in­ dicate Pauli paramagnetism for YbAgCd and Curie-Weiss behavior above 60 K for EuAgCd with an experimental magnetic moment of 7.82(3) μB/Eu indicating divalent ytterbium and europium. Ferromagnetic ordering at Tc = 28.0(5) K is observed for EuAgCd. At 2 K and 5 T the saturation magnetization is 5.85(5) μB/Eu.

2001 ◽  
Vol 56 (6) ◽  
pp. 463-468 ◽  
Author(s):  
Ratikanta Mishra ◽  
Rainer Pöttgen ◽  
Gunter Kotzyba

AbstractThe metal-rich intermetallic compounds NblrSi, NblrGe, and TalrSi were synthesized by arc-melting of the elements and subsequent annealing in glassy carbon crucibles in a high-frequency furnace. The three compounds were investigated by X-ray diffraction on powders and single crystals: TiNiSi type, Pnma, a = 641.27(3), b = 379.48(2), c = 727.70(3) pm, wR2 = 0.0773, 430 F2 values for NblrSi, a = 645.48(3), b = 389.21(2), c = 741.11(4) pm, wR2 = 0.0981, 297 F2 values for NblrGe, and a = 638.11(3), b = 378.69(2), c = 726.78(3) pm, wR2 = 0.0887, 290 F2 values for TalrSi with 20 variables for each refinement. The iridium and silicon (germanium) atoms form a three-dimensional network of puckered Ir3Si3 and Ir3Ge3 hexagons in which the niobium (tantalum) atoms fill larger cages. Magnetic susceptibility measurements on NblrSi and TalrSi indicate Pauli paramagnetism with room temperature susceptibilities of 0.30(5)·10-9 and 0.97(5)·10-9 m3/mol, respectively.


2007 ◽  
Vol 62 (5) ◽  
pp. 642-646 ◽  
Author(s):  
Selcan Tuncel ◽  
Ute Ch. Rodewald ◽  
Bernard Chevalier ◽  
Rainer Pöttgen

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.


2011 ◽  
Vol 66 (7) ◽  
pp. 671-676 ◽  
Author(s):  
Trinath Mishra ◽  
Rainer Pöttgen

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.


2019 ◽  
Vol 75 (2) ◽  
pp. 141-149 ◽  
Author(s):  
Feng Su ◽  
Cheng-Yong Zhou ◽  
Lin-Tao Wu ◽  
Xi Wu ◽  
Chun Han ◽  
...  

Coordination polymers constructed from conjugated organic ligands and metal ions with a d 10 electronic configuration exhibit intriguing properties for chemical sensing and photochemistry. A ZnII-based coordination polymer, namely poly[aqua(μ6-biphenyl-3,3′,5,5′-tetracarboxylato)(μ2-4,4′-bipyridine)dizinc(II)], [Zn2(C16H6O8)(C10H8N2)(H2O)2] n or [Zn2(m,m-bpta)(4,4′-bipy)(H2O)2] n , was synthesized from a mixture of biphenyl-3,3′,5,5′-tetracarboxylic acid [H4(m,m-bpta)], 4,4′-bipyridine (4,4′-bipy) and Zn(NO3)2·6H2O under solvothermal conditions. The title complex has been structurally characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction analysis, and features a μ6-coordination mode. The ZnII ions adopt square-pyramidal geometries and are bridged by two syn–syn carboxylate groups to form [Zn2(COO)2] secondary buildding units (SBUs). The SBUs are crosslinked by (m,m-bpta)4− ligands to produce a two-dimensional grid-like layer that exhibits a stair-like structure along the a axis. Adjacent layers are linked by 4,4′-bipy ligands to form a three-dimensional network with a {44.610.8}{44.62} topology. In the solid state, the complex displays a strong photoluminescence and an excellent solvent stability. In addition, the luminescence sensing results indicate a highly selective and sensitive sensing for Fe3+ ions.


1997 ◽  
Vol 52 (2) ◽  
pp. 256-258 ◽  
Author(s):  
Evgeni V. Avtomonov ◽  
Rainer Grüning ◽  
Jörg Lorberth

Abstract The crystal structure of the title compound has been determined by X-ray diffraction methods. Due to the Lewis acidic character of the iodine substituent a “zig-zag” chain is formed via intermolecular interactions (2.933(4) A) between iodine and oxygen atoms of theocarbamate moiety. A three-dimensional network is formed through hydrogen-bridging (2.04 A) between NH-groups and the oxygen atoms of the neighbouring carbamate group of the next molecule.


2006 ◽  
Vol 61 (2) ◽  
pp. 159-163 ◽  
Author(s):  
Rainer Kraft ◽  
Sudhindra Rayaprol ◽  
C. Peter Sebastian ◽  
Rainer Pöttgen

AbstractThe new thallide EuPdTl2, synthesized from the elements in a sealed tantalum tube in a highfrequency furnace, was investigated by X-ray diffraction on powders and single crystals: MgCuAl2 type, Cmcm, Z = 4, a = 446.6(1), b = 1076.7(2), c = 812.0(2) pm, wR2 = 0.0632, 336 F2 values, 16 variables. The structure can be considered as an orthorhombically distorted, palladium-filled variant of the binary Zintl phase EuTl2. The palladium and thallium atoms build up a three-dimensional [PdTl2] polyanion with significant Pd-Tl (286 - 287 pm) and Tl-Tl (323 - 329 pm) interactions. The europium atoms fill distorted hexagonal channels of the [PdTl2] polyanion. Susceptibility measurements show a magnetic moment of 7.46(5) μB/Eu atom, indicative of divalent europium. EuPdTl2 is a soft ferromagnet with a Curie temperature of TC = 12.5(5) K.


2015 ◽  
Vol 71 (1) ◽  
pp. 48-52 ◽  
Author(s):  
José J. Campos-Gaxiola ◽  
Susana P. Arredondo Rea ◽  
Ramón Corral Higuera ◽  
Herbert Höpfl ◽  
Adriana Cruz Enríquez

Two organic–inorganic hybrid compounds have been prepared by the combination of the 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium cation with perhalometallate anions to give 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium tetrachloridocobaltate(II), (C12H12N2)[CoCl4], (I), and 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium tetrachloridozincate(II), (C12H12N2)[ZnCl4], (II). The compounds have been structurally characterized by single-crystal X-ray diffraction analysis, showing the formation of a three-dimensional network throughX—H...ClnM−(X= C, N+;n= 1, 2;M= CoII, ZnII) hydrogen-bonding interactions and π–π stacking interactions. The title compounds were also characterized by FT–IR spectroscopy and thermogravimetric analysis (TGA).


2003 ◽  
Vol 58 (12) ◽  
pp. 722-726 ◽  
Author(s):  
A. Waśkowska ◽  
S. Dacko ◽  
Z. Czapla

Crystals of [(CH2OH)3CNH3]H2AsO4 have been grown, and X-ray diffraction analysis has shown them to be monoclinic, with space group P21. A three-dimensional network of hydrogen bonds of the type O-H. . . O and N-H. . . O forms strong cation-cation and cation-anion linkages. Stabilizing the structure, they create favourable conditions in the crystal to be polar. The temperature dependent behaviour of the dielectric permittivity, measured along three crystal axes in the range 100 - 300 K, did not show any evidence for a phase transition, while the pyroelectric properties of the crystal confirmed the lack of a centre of symmetry. These polar features locate [(CH2OH)3CNH3]H2AsO4 among the materials applicable to electrooptics and for the second harmonic generation.


Author(s):  
Mwaffak Rukiah ◽  
Thaer Assaad

The title two-dimensional coordination polymer, [Na(C2H8NO6P2)]n, was characterized using powder X-ray diffraction data and its structure refined using the Rietveld method. The asymmetric unit contains one Na+cation and one (1-azaniumylethane-1,1-diyl)bis(hydrogen phosphonate) anion. The central Na+cation exhibits distorted octahedral coordination geometry involving two deprotonated O atoms, two hydroxy O atoms and two double-bonded O atoms of the bisphosphonate anion. Pairs of sodium-centred octahedra share edges and the pairs are in turn connected to each other by the biphosphonate anion to form a two-dimensional network parallel to the (001) plane. The polymeric layers are connected by strong O—H...O hydrogen bonding between the hydroxy group and one of the free O atoms of the bisphosphonate anion to generate a three-dimensional network. Further stabilization of the crystal structure is achived by N—H...O and O—H...O hydrogen bonding.<!?tpb=18.7pt>


1994 ◽  
Vol 49 (9) ◽  
pp. 1256-1262 ◽  

Crystals of KCoPO4 were obtained by growth in a gel of tetramethoxysilane/water at 64 °C. The hexagonal crystals have space group P63, a = 18.206(1), c = 8.5135(8) [Å], V = 2443.8(4) [Å3]. Z = 24. The structure was solved by single crystal X-ray diffraction methods. The structure is isotypic with α-KZnPO4. It comprises an ordered three dimensional network of alternating CoO4 and PO4 tetrahedra. which has rings of six tetrahedra in the xy plane. These rings form tunnels in the [001] direction, where the potassium ions are located. Upon heating, the compound undergoes a phase transition at about 565 °C; on cooling, the phase transition occurs at 449 °C, where it transforms into another structure which is yet unknown. This indicates that the hexagonal structure is a metastable phase


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