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Title: Structural characterization, magnetic behavior and high-resolution EELS study of new perovskites Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5)

Abstract

New oxides of general formula Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5) have been synthesized as polycrystalline materials and characterized structurally by X-ray diffraction. For 0.5{<=}x<0.67 the orthorhombic, Pnma, perovskite structure of the end member, SrRuO{sub 3}, is found. At x=0.67 a phase separation into an Ru-rich Pnma phase and a Co-rich I2/c phase occurs. The I2/c form is also found for x=1.0 but another orthorhombic phase, Imma, obtains for x=1.33 and 1.5. Reductive weight losses indicate negligible oxygen non-stoichiometry, i.e., {delta}{approx}0, for all compositions even those rich in Co. High-resolution electron energy loss spectroscopy (EELS) indicates that cobalt is high-spin Co{sup 3+} or high-spin Co{sup 4+} for all x. Appropriate combinations of Ru{sup 4+}, Ru{sup 5+}, HS Co{sup 3+} and HS Co{sup 4+} are proposed for each x which are consistent with the observed Ru(Co)-O distances. Significant amounts of Co{sup 4+} must be present for large x values to explain the short observed distances. Broad maxima in the d.c. susceptibilities are found between 78 and 97 K with increasing x, along with zero-field-cooled (ZFC) and field-cooled (FC) divergences suggesting glassy magnetic freezing. A feature near 155 K for all samples indicates a residualmore » amount of ferromagnetic SrRuO{sub 3} not detected by X-ray diffraction. - Graphical abstract: Correlation between the average B-site radius, the Goldschmidt tolerance factor and the sequence of space groups and Glazer tilt systems found for the perovskite solid solution Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6}.« less

Authors:
 [1];  [2];  [3];  [1];  [2];  [4];  [5];  [1];  [1]
  1. Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ont., L8S 4M1 (Canada)
  2. (Canada)
  3. (Spain), E-mail: lozano@mcmaster.ca
  4. Departamento de Quimica Inorganica, Universidad de La Laguna, 38206-La Laguna, Tenerife (Spain)
  5. Departamento de Fisica Fundamental II, Universidad de La Laguna, 38200-La Laguna, Tenerife (Spain)
Publication Date:
OSTI Identifier:
21015766
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 4; Other Information: DOI: 10.1016/j.jssc.2007.01.019; PII: S0022-4596(07)00036-9; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COBALT COMPOUNDS; COBALT IONS; ENERGY-LOSS SPECTROSCOPY; ION MICROPROBE ANALYSIS; MAGNETISM; MONOCLINIC LATTICES; ORTHORHOMBIC LATTICES; OXIDES; OXYGEN; PEROVSKITE; POLYCRYSTALS; RUTHENIUM COMPOUNDS; RUTHENIUM IONS; SOLID SOLUTIONS; SOLUBILITY; SPACE GROUPS; SPIN; STRONTIUM COMPOUNDS; TETRAGONAL LATTICES; X-RAY DIFFRACTION

Citation Formats

Lozano-Gorrin, A.D., Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1, Departamento de Quimica Inorganica, Universidad de La Laguna, 38206-La Laguna, Tenerife, Greedan, J.E., Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1, Nunez, P., Gonzalez-Silgo, C., Botton, G.A., and Radtke, G. Structural characterization, magnetic behavior and high-resolution EELS study of new perovskites Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5). United States: N. p., 2007. Web. doi:10.1016/j.jssc.2007.01.019.
Lozano-Gorrin, A.D., Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1, Departamento de Quimica Inorganica, Universidad de La Laguna, 38206-La Laguna, Tenerife, Greedan, J.E., Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1, Nunez, P., Gonzalez-Silgo, C., Botton, G.A., & Radtke, G. Structural characterization, magnetic behavior and high-resolution EELS study of new perovskites Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5). United States. doi:10.1016/j.jssc.2007.01.019.
Lozano-Gorrin, A.D., Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1, Departamento de Quimica Inorganica, Universidad de La Laguna, 38206-La Laguna, Tenerife, Greedan, J.E., Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1, Nunez, P., Gonzalez-Silgo, C., Botton, G.A., and Radtke, G. Sun . "Structural characterization, magnetic behavior and high-resolution EELS study of new perovskites Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5)". United States. doi:10.1016/j.jssc.2007.01.019.
@article{osti_21015766,
title = {Structural characterization, magnetic behavior and high-resolution EELS study of new perovskites Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5)},
author = {Lozano-Gorrin, A.D. and Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1 and Departamento de Quimica Inorganica, Universidad de La Laguna, 38206-La Laguna, Tenerife and Greedan, J.E. and Department of Chemistry, McMaster University, 1280 Main Street W., Hamilton, Ont., L8S 4M1 and Nunez, P. and Gonzalez-Silgo, C. and Botton, G.A. and Radtke, G.},
abstractNote = {New oxides of general formula Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6-} {sub {delta}} (0.5{<=}x{<=}1.5) have been synthesized as polycrystalline materials and characterized structurally by X-ray diffraction. For 0.5{<=}x<0.67 the orthorhombic, Pnma, perovskite structure of the end member, SrRuO{sub 3}, is found. At x=0.67 a phase separation into an Ru-rich Pnma phase and a Co-rich I2/c phase occurs. The I2/c form is also found for x=1.0 but another orthorhombic phase, Imma, obtains for x=1.33 and 1.5. Reductive weight losses indicate negligible oxygen non-stoichiometry, i.e., {delta}{approx}0, for all compositions even those rich in Co. High-resolution electron energy loss spectroscopy (EELS) indicates that cobalt is high-spin Co{sup 3+} or high-spin Co{sup 4+} for all x. Appropriate combinations of Ru{sup 4+}, Ru{sup 5+}, HS Co{sup 3+} and HS Co{sup 4+} are proposed for each x which are consistent with the observed Ru(Co)-O distances. Significant amounts of Co{sup 4+} must be present for large x values to explain the short observed distances. Broad maxima in the d.c. susceptibilities are found between 78 and 97 K with increasing x, along with zero-field-cooled (ZFC) and field-cooled (FC) divergences suggesting glassy magnetic freezing. A feature near 155 K for all samples indicates a residual amount of ferromagnetic SrRuO{sub 3} not detected by X-ray diffraction. - Graphical abstract: Correlation between the average B-site radius, the Goldschmidt tolerance factor and the sequence of space groups and Glazer tilt systems found for the perovskite solid solution Sr{sub 2}Ru{sub 2-} {sub x} Co {sub x} O{sub 6}.},
doi = {10.1016/j.jssc.2007.01.019},
journal = {Journal of Solid State Chemistry},
number = 4,
volume = 180,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • Structural and magnetic studies are presented for the perovskite type Sr{sub 1-x}La{sub x}Co{sub 0.5}Fe{sub 0.5}O{sub 3-{delta}} (0{<=}x{<=}0.5) materials annealed under moderately high-oxygen pressures of {approx}200 atm. A detailed analysis of the room temperature neutron time-of-flight diffraction data reveals that the crystal structure of the sample SrCo{sub 0.5}Fe{sub 0.5}O{sub 2.89(1)}, previously described as vacancy-disordered cubic, is similar to the formerly reported, oxygen-vacancy ordered Sr{sub 8}Fe{sub 8}O{sub 23} compound, i.e. Sr{sub 8}Co{sub 4}Fe{sub 4}O{sub 23} is tetragonal with the I4/mmm symmetry. With an increase of the La content the studied materials become nearly oxygen stoichiometric and a lowering of the crystal symmetrymore » is observed from cubic Pm3-barm (x=0.1 and 0.2) to tetragonal I4/mcm (x=0.3 and 0.4), and finally to monoclinic I12/c1 (x=0.5). Low-temperature structural and magnetic measurements show a ferromagnetic ordering with the maximum Curie temperature near 290 K at x=0.2. - Graphical Abstract: Room temperature Rietveld refinement profile using I4/mmm space group for the oxygen vacancy ordered SrCo{sub 0.5}Fe{sub 0.5}O{sub 2.89} (Sr{sub 8}Co{sub 4}Fe{sub 4}O{sub 23}). Top tick-marks denote allowed reflections in I4/mmm, bottom one emphasize the possibility of inexact indexing using Pm3-barm symmetry. Previous reports indicate that similar ordering is common for SrCo{sub 1-x}Fe{sub x}O{sub 3-{delta}} compounds possibly hindering their applications.« less
  • The structural parameters, phase purity, and oxygen stoichiometry of the (Pr{sub 1.5}Ce{sub 0.5})Sr{sub 2}Cu{sub 2}TaO{sub 10-{delta}} and (R{sub 1.5}-{sub x}Pr{sub x} Ce{sub 0.5}) Sr{sub 2}Cu{sub 2}NbO{sub 10-{delta}}, R = Nd, Sm, Eu, compounds are investigated with powder X-ray diffraction (XRD), Rietveld refinements, and thermogravimetric analysis (TGA). The XRD data indicate that all the (R{sub 1.5-x}Pr{sub x}Ce{sub 0.5})Sr{sub 2}Cu{sub 2}NbO{sub 10-{delta}} compounds are isostructural and typically 98% pure. Rietveld refinements reveal a contraction of the c lattice parameter and features in the rare earth-planar oxygen bond length (as functions of Pr doping) that are correlated with the unusual electronic and magneticmore » transitions induced by the Pr ion in these materials. Results for deoxygenated samples show that the lattice expands upon deoxygenation and suggest that the oxygen is removed primarily from the SrO layers. TGA results reveal reliable techniques for determining oxygen stoichiometries and deoxygenating these compounds and that these compounds are oxygen deficient with {delta}`s of typically 0.045. The structural features of these compounds are compared to similar high T{sub c}, cuprates, and related to the electronic and magnetic transitions and the suppression of superconductivity induced by the Pr ion in these materials. We discuss our results in terms of the current understanding of high T{sub c} cuprates and models for the suppression of superconductivity by the Pr ion in the related (R{sub 1-x}Pr{sub x})Ba{sub 2}Cu{sub 3}O{sub 7} system.« less
  • 6-H perovskites with compositions Ba{sub 2}Co{sub 2-x}Sb{sub x}O{sub 6-y}, 0.6{<=}x{<=}0.8 and x=1.33 (Ba{sub 3}CoSb{sub 2}O{sub 9}) have been prepared in air at 1150 deg. C. Refinements of the crystal structures of Ba{sub 2}Co{sub 1.4}Sb{sub 0.6}O{sub 6-y} and Ba{sub 3}CoSb{sub 2}O{sub 9} were performed in space group P6{sub 3}/mmc, using neutron and X-ray powder diffraction data, respectively: Ba{sub 2}Co{sub 1.4}Sb{sub 0.6}O{sub 6-y} a=5.7315(1) A, c=14.1118(4) A, R{sub F}{sup 2}=0.0669, R{sub p}=0.0464, {chi}{sup 2}=1.39; Ba{sub 3}CoSb{sub 2}O{sub 9} a=5.85321(7) A, c=14.4454(2) A, R{sub F}{sup 2}=0.0458, R{sub p}=0.0258, {chi}{sup 2}=1.24. In Ba{sub 3}CoSb{sub 2}O{sub 9} the antimony atoms are located in pairs ofmore » face-sharing octahedra separated by cobalt atoms in octahedral layers, while in Ba{sub 2}Co{sub 1.4}Sb{sub 0.6}O{sub 6-y} a random distribution of B cations was found. In the latter structure, oxygen vacancies are preferably located in BaO{sub 3} planes separating the face-sharing octahedra. Electron diffraction and high-resolution electron microscopy studies showed that the structures are well ordered. Results of the magnetic susceptibility measurements of Ba{sub 3}CoSb{sub 2}O{sub 9} and Ba{sub 2}Co{sub 1.4}Sb{sub 0.6}O{sub 6-y} are reported.« less
  • The crystal structures of Sr{sub 2}CaMoO{sub 6} and Sr{sub 2}CaTeO{sub 6} have been determined at room temperature by neutron powder diffraction. Both compounds crystallize in the perovskite structure with a rock-salt ordered array of Ca{sup 2+} and M{sup 6+} cations (M=Mo, Te) on the six-coordinate sites (space group P2{sub 1}/n (no. 14); for M=Mo, a=5.76228(7), b=5.84790(7), c=8.18707(9)A, {beta}=90.194(1){sup o}, for M=Te, a=5.79919(9), b=5.83756(8), c=8.2175(1)A, {beta}=90.194(1){sup o}). Compositions in the solid solution Sr{sub 2}CaMo{sub 1-x}Te{sub x}O{sub 6} have been synthesized and shown by X-ray diffraction to adopt the same ordered structure. The results are used in a discussion of the cationmore » oxidation states in Ca{sub 2}FeMoO{sub 6} and to establish the similarity between the structural chemistry of hexavalent Mo and Te.« less
  • The reaction of Ru[sub 4]Pt[sub 2](CO)[sub 18] with Ru[sub 4](CO)[sub 13]([mu]-H)[sub 2] at 97[degrees]C yielded the new decanuclear platinum-ruthenium carbonyl cluster complex Ru[sub 8]Pt[sub 2](CO)[sub 23]([mu][sub 3]-H)[sub 2] 1 (22%). In a similar manner the reaction of Ru[sub 4]Pt[sub 2](CO)[sub 18] with Ru[sub 3]Pt(CO)[sub 10](COD)([mu]-H)[sub 2], 2, in 25% yield. Both compounds were characterized by IR, [sup 1]H NMR, and single-crystal X-ray diffraction analyses, and both were bound to consist of similar edge-fused bioctahedral clusters with platinum atoms along the edge-sharing sites. There are strong metal-metal bonds between the apices of the adjacent octahedra. Both compounds are electron deficient, andmore » one of the apical-apical Ru-Ru bonds is unusually short, 2.580 (2) [Angstrom] in 1 and 2.593 (5) [Angstrom] in 2. The hydrides are triply bridging ligands, and these were located and refined crystallographically in 1. The reaction of 1 with 1,2-bis(diphenylphosphino)ethane, dppe, yielded the adduct Ru[sub 8]Pt[sub 2](CO)[sub 21]([mu][sub 3]-CO)[sub 2](dppe)([mu]-H)[sub 2], 3, in 12% yield, which was shown to consist of a face-shared bioctahedral cluster of seven ruthenium and two platinum atoms with a ruthenium spike containing the dppe ligand extending from one triruthenium face. Two novel dihapto-triply bridging carbonyl ligands were found to bridge to the ruthenium spike. 1 and 2 both react with CO at 25[degrees]C, but only the product obtained from the reaction of 2, Ru[sub 6]Pt[sub 3](CO)[sub 21]([mu]-CO)([mu][sub 3]-H)[sub 2], 4, (55% yields), could be fully characterized. It was shown to contain a cluster of nine metal atoms arranged into trinuclear layers of pure ruthenium and pure platinum. The two triply bridging hydride ligands were located and refined crystallographically. 23 refs., 4 figs., 13 tabs.« less