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Title: Hole doping into Co-12s2 copper oxides with s fluorite-structured layers between CuO{sub 2} planes

Abstract

In this work, the first three members (s=1, 2, 3) of the Co-12s2 homologous series of multi-layered copper oxides are gradually doped with holes through high-pressure oxygenation (HPO). The phases differ from each other only by thickness of the fluorite-structured layer block (Ce,Y,Ca)-[O{sub 2}-(Ce,Y)]{sub s-1}, between two identical CuO{sub 2} planes. High-resolution transmission-electron microscopy (HRTEM) and electron diffraction (ED) analyses together with both synchrotron X-ray and neutron powder diffraction data, reveal that as a consequence of HPO the charge-reservoir CoO{sub 4}-tetrahedra chains get broken and the lattice symmetry of the Co-12s2 phases changes from orthorhombic to tetragonal. Oxygen contents are analyzed for the samples with wet-chemical and thermogravimetric techniques. The valence state of copper in the CuO{sub 2} plane is determined from Cu L-edge X-ray absorption near-edge structure (XANES) spectra to be compared with the values estimated through bond-valence-sum (BVS) calculations from the crystal structure data. The positive charge induced by oxygen loading (or aliovalent Ca{sup II}-for-Y{sup III} substitution in CoSr{sub 2}YCu{sub 2}O{sub 7+{delta}}) is found not to be completely accommodated in the CuO{sub 2} planes but be rather effectively trapped at the charge-reservoir Co atoms. Superconductivity appears in the Co-1212 (CoSr{sub 2}YCu{sub 2}O{sub 7+{delta}}) samples with the copper valencemore » of 2.13 or higher, whereas in the Co-1222 (CoSr{sub 2}(Ce{sub 0.25}Y{sub 0.75}){sub 2}Cu{sub 2}O{sub 9+{delta}}) and Co-1232 (CoSr{sub 2}(Ce{sub 0.67}Y{sub 0.33}){sub 3}Cu{sub 2}O{sub 11+{delta}}) samples Cu valence does not increase high enough to induce superconductivity.« less

Authors:
 [1];  [2];  [1];  [3];  [4];  [4];  [5];  [6];  [1];  [7];  [3];  [1];  [8]
  1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
  2. (Norway)
  3. National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)
  4. National Synchrotron Radiation Research Center, Hsinchu, Taiwan, ROC (China)
  5. Department of Chemistry, National Taiwan University, Taipei, Taiwan, ROC (China)
  6. Institute for Energy Technology, N-2027 Kjeller (Norway)
  7. (India)
  8. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan). E-mail: karppinen@msl.titech.ac.jp
Publication Date:
OSTI Identifier:
20784904
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 179; Journal Issue: 3; Other Information: DOI: 10.1016/j.jssc.2005.11.025; PII: S0022-4596(05)00538-4; Copyright (c) 2005 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; ABSORPTION SPECTROSCOPY; COPPER OXIDES; DOPED MATERIALS; FLUORITE; HOLES; LAYERS; NEUTRON DIFFRACTION; ORTHORHOMBIC LATTICES; SUPERCONDUCTIVITY; THERMAL GRAVIMETRIC ANALYSIS; TRANSMISSION ELECTRON MICROSCOPY; VALENCE; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY

Citation Formats

Fjellvag, H., Centre for Materials Science and Nanotechnology, University of Oslo, N-0315 Oslo, Morita, Y., Nagai, T., Lee, J.-M., Chen, J.-M., Liu, R.-S., Hauback, B.C., Awana, V.P.S., National Physical Laboratory, Krishnan Matg, New Delhi 12, Matsui, Y., Yamauchi, H., and Karppinen, M. Hole doping into Co-12s2 copper oxides with s fluorite-structured layers between CuO{sub 2} planes. United States: N. p., 2006. Web. doi:10.1016/j.jssc.2005.11.025.
Fjellvag, H., Centre for Materials Science and Nanotechnology, University of Oslo, N-0315 Oslo, Morita, Y., Nagai, T., Lee, J.-M., Chen, J.-M., Liu, R.-S., Hauback, B.C., Awana, V.P.S., National Physical Laboratory, Krishnan Matg, New Delhi 12, Matsui, Y., Yamauchi, H., & Karppinen, M. Hole doping into Co-12s2 copper oxides with s fluorite-structured layers between CuO{sub 2} planes. United States. doi:10.1016/j.jssc.2005.11.025.
Fjellvag, H., Centre for Materials Science and Nanotechnology, University of Oslo, N-0315 Oslo, Morita, Y., Nagai, T., Lee, J.-M., Chen, J.-M., Liu, R.-S., Hauback, B.C., Awana, V.P.S., National Physical Laboratory, Krishnan Matg, New Delhi 12, Matsui, Y., Yamauchi, H., and Karppinen, M. Wed . "Hole doping into Co-12s2 copper oxides with s fluorite-structured layers between CuO{sub 2} planes". United States. doi:10.1016/j.jssc.2005.11.025.
@article{osti_20784904,
title = {Hole doping into Co-12s2 copper oxides with s fluorite-structured layers between CuO{sub 2} planes},
author = {Fjellvag, H. and Centre for Materials Science and Nanotechnology, University of Oslo, N-0315 Oslo and Morita, Y. and Nagai, T. and Lee, J.-M. and Chen, J.-M. and Liu, R.-S. and Hauback, B.C. and Awana, V.P.S. and National Physical Laboratory, Krishnan Matg, New Delhi 12 and Matsui, Y. and Yamauchi, H. and Karppinen, M.},
abstractNote = {In this work, the first three members (s=1, 2, 3) of the Co-12s2 homologous series of multi-layered copper oxides are gradually doped with holes through high-pressure oxygenation (HPO). The phases differ from each other only by thickness of the fluorite-structured layer block (Ce,Y,Ca)-[O{sub 2}-(Ce,Y)]{sub s-1}, between two identical CuO{sub 2} planes. High-resolution transmission-electron microscopy (HRTEM) and electron diffraction (ED) analyses together with both synchrotron X-ray and neutron powder diffraction data, reveal that as a consequence of HPO the charge-reservoir CoO{sub 4}-tetrahedra chains get broken and the lattice symmetry of the Co-12s2 phases changes from orthorhombic to tetragonal. Oxygen contents are analyzed for the samples with wet-chemical and thermogravimetric techniques. The valence state of copper in the CuO{sub 2} plane is determined from Cu L-edge X-ray absorption near-edge structure (XANES) spectra to be compared with the values estimated through bond-valence-sum (BVS) calculations from the crystal structure data. The positive charge induced by oxygen loading (or aliovalent Ca{sup II}-for-Y{sup III} substitution in CoSr{sub 2}YCu{sub 2}O{sub 7+{delta}}) is found not to be completely accommodated in the CuO{sub 2} planes but be rather effectively trapped at the charge-reservoir Co atoms. Superconductivity appears in the Co-1212 (CoSr{sub 2}YCu{sub 2}O{sub 7+{delta}}) samples with the copper valence of 2.13 or higher, whereas in the Co-1222 (CoSr{sub 2}(Ce{sub 0.25}Y{sub 0.75}){sub 2}Cu{sub 2}O{sub 9+{delta}}) and Co-1232 (CoSr{sub 2}(Ce{sub 0.67}Y{sub 0.33}){sub 3}Cu{sub 2}O{sub 11+{delta}}) samples Cu valence does not increase high enough to induce superconductivity.},
doi = {10.1016/j.jssc.2005.11.025},
journal = {Journal of Solid State Chemistry},
number = 3,
volume = 179,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • The hole distribution within a CuO{sub 2} plane, a common structural element of high-temperature superconductors, is investigated as a function of doping by holes. The correlated ground state of a three-band Hubbard model is found by making use of a {ital local ansatz} which includes local correlations between holes. It is found that doped holes have {similar to}70% oxygen character for the parameters determined from the local-density approximation, in agreement with experimental observations, while hole droplets on oxygen orbitals are formed for large copper-oxygen Coulomb repulsion, {ital U}{sub {ital dp}}. All our results agree with those obtained from finite-cluster diagonalization.
  • By comparing structural and superconducting properties of La{sub 2{minus}{ital x}{minus}{ital y}}Ca{sub {ital x}}Nd{sub {ital y}}CuO{sub 4} to La{sub 2{minus}{ital x}}Sr{sub {ital x}}CuO{sub 4} we have separated the effects of structure and doping on the superconducting {ital T}{sub {ital c}}. At a fixed doping level, the highest {ital T}{sub {ital c}} is found for flat and square CuO{sub 2} planes in the tetragonal structure. {ital T}{sub {ital c}} is reduced by the structural distortions of the CuO{sub 2} planes in the orthorhombic structure. The local minimum of {ital T}{sub {ital c}} vs doping observed around {ital x}{approximately}0.12 indicates the presence ofmore » a weakly split singularity of the electronic density of states for the orthorhombic material. {copyright} {ital 1996 The American Physical Society.}« less
  • We demonstrate that the T{sub c} value of superconductive copper oxides does not depend on the distance between two adjacent CuO{sub 2} planes as long as the hole-doping level and the immediate (crystal) chemical surroundings of the planes are kept the same. Experimental evidence is accomplished for the homologous series of (Cu,Mo)-12s2, the member phases of which differ from each other by the number (s) of cation layers in the fluorite-structured (Ce,Y)-[O{sub 2}-(Ce,Y)]{sub s-1} block between the CuO{sub 2} planes. X-ray absorption near-edge structure spectroscopy is employed as a probe for the hole states of these phases. The s =more » 1 member appears to be more strongly doped with holes than other phases of the series and accordingly to possess the highest T{sub c} value of 87 K. For s {ge} 2, unexpectedly, both the CuO{sub 2} plane hole concentration and the value of T{sub c} ({approx}55 K) remain constant, being independent of s.« less
  • Superconductivity characteristics have been systematically evaluated for a two-CuO{sub 2}-plane copper oxide system (Cu,Mo)-12s2, upon increasing the number of fluorite-structured layers, s, between the two CuO{sub 2} planes. Essentially single-phase samples of (Cu{sub 0.75}Mo{sub 0.25})Sr{sub 2}YCu{sub 2}O{sub 7+{delta}} (s=1), (Cu{sub 0.75}Mo{sub 0.25})Sr{sub 2}(Ce{sub 0.45}Y{sub 0.55}){sub 2}Cu{sub 2}O{sub 9+{delta}} (s=2) and (Cu{sub 0.75}Mo{sub 0.25})Sr{sub 2}(Ce{sub 0.67}Y{sub 0.33}){sub 3}Cu{sub 2}O{sub 11+{delta}} (s=3) were synthesized through a conventional solid-state route in air. To make the samples superconductive an additional high-pressure oxygenation (HPO) treatment was required. Such treatment (carried out at 5GPa and 500 deg. C in the presence of 75mol% Ag{sub 2}O{sub 2}more » as an oxygen source to maximize the T{sub c}) compressed the crystal lattice for the three members of the (Cu{sub 0.75}Mo{sub 0.25})-12s2 series equally, i.e., by 0.01A for the a parameter and by 0.07A for the c parameter per formula unit. From both Cu L-edge and O K-edge XANES spectra the s=1 sample was found to possess the highest overall hole-doping level among the HPO samples. Accordingly it exhibited the best superconductivity characteristics. With increasing s, both the T{sub c} (s=1: 88K, s=2: 61K, s=3: 53K) and H{sub irr} values got depressed, being well explained by the trend of decreasing CuO{sub 2}-plane hole concentration with increasing s as revealed from O K-edge XANES spectra for the same samples. Hence, the present results do not suggest any significant (negative) impact on the superconductivity characteristics from the gradually thickened fluorite-structured block itself.« less