Structure-property relationships in pyrochlores: low-temperature structures of Tl2Ru2O7-δ (δ=0.00 and 0.05)

(Note: The full text of this document is currently only available in the PDF Version )

T. Takeda, R. Kanno, Y. Kawamoto, M. Takano, F. Izumi, A. W. Sleight and A. W. Hewat


Abstract

Structural, electrical and magnetic properties are investigated for ruthenium pyrochlores. The structure of the thallium ruthenium pyrochlore, Tl2Ru2O7–δ, has been determined for δ=0.00 and 0.05 by neutron diffraction measurements at low temperatures. Stoichiometric Tl2Ru2O7.00 synthesized under a high oxygen pressure of 3 GPa using KClO4 shows a first-order metallic-semiconducting transition at 120 K. The high-temperature metallic phase has a cubic pyrochlore structure with a three dimensional network of both ruthenium fand thallium. The low-temperature semiconducting phase has thallium sites with slightly short and long Tl-O distances, and the two Tl sites are ordered one dimensionally in the orthorhombic cell. Charge disproportionation of the Tl ions was suggested by valence bond sum calculations. By contrast, non-stoichiometric Tl2Ru2O6.95 showed a spin-glass-like or canted-spin behavior around 40 K with resistivity increase also observed at this temperature. No significant structure changes were observed at the transition. Metallic-semiconducting transitions are discussed on the basis of their bond distance and angle changes.


References

  1. R. J. Bouchard and J. L. Gillson, Mater. Res. Bull., 1971, 6, 69 CrossRef.
  2. J. M. Longo, P. M. Raccah and J. B. Goodenough, Mater. Res. Bull., 1969, 4, 191 CrossRef CAS.
  3. R. Aleonard, A. F. Berthand, M. C. Montomry and R. Pauthenet, J. Appl. Phys., 1962, 33, 1205 CAS.
  4. A. W. Sleight and R. J. Bouchard, Solid State Chemistry, Proceedings of 5th Materials Research Symposium, July 1972, NBS Spec. Publ. 364, p. 227 Search PubMed.
  5. H. S. Jarrett, A. W. Sleight, J. F. Weiher, J. L. Gillson, C. G. Frederick, G. A. Jones, R. S. Swingle, D. Swartzfager, J. E. Gulley and P. C. Hoell, Valence Instabilities and Related Narrow-Band Phenomena, ed. R. D. Parks, Plenum, New York, 1977, p. 545 Search PubMed.
  6. J. B. Goodenough, A. Hamnett, D. Telles, Localization and Metal–Insulator Transition, ed. H. Fritzshe and D. Adler, Plenum, New York, 1985, p. 161 Search PubMed.
  7. P. A. Cox, J. B. Goodenough, P. J. Tavener, D. Telles and R. G. Egdell, J. Solid State Chem., 1986, 62, 360 CAS.
  8. P. A. Cox, R. G. Egdell, J. B. Goodenough, A. Hamnett and C. C. Naish, J. Phys. C, 1983, 16, 6221 CrossRef CAS.
  9. W. Y. Hsu, R. V. Kasowski, T. Miller and T.-C. Chiang, Appl. Phys. Lett., 1988, 52, 792 CrossRef CAS.
  10. R. Kanno, J. Huang, and A. W. Sleight, Proceedings of the Fifth International Symposium on Advanced Nuclear Energy Research, Neutrons as Microscopic Probes, March 1993, JAERI-M 93, 228, vol. 2, p. 347 Search PubMed.
  11. T. Takeda, M. Nagata, H. Kobayashi, R. Kanno, Y. Kawamoto, M. Takano, T. Kamiyama, F. Izumi, and A. W. Sleight, J. Solid State Chem., in press Search PubMed.
  12. R. Kanno, Y. Takeda, T. Yamamoto, Y. Kawamoto and O. Yamamoto, J. Solid State Chem., 1993, 102, 106 CrossRef CAS.
  13. T. Yamamoto, R. Kanno, Y. Takeda, O. Yamamoto, Y. Kawamoto and M. Takano, J. Solid State Chem., 1994, 109, 372 CrossRef CAS.
  14. H. Kobayashi, R. Kanno, Y. Kawamoto, T. Kamiyama, F. Izumi and A. W. Sleight, J. Solid State Chem., 1995, 114, 15 CrossRef CAS.
  15. K.-S. Lee, D.-K. Seo and M.-H. Whangbo, J. Solid State Chem., 1997, 131, 405 CrossRef CAS.
  16. B. J. Kennedy and T. Vogt, J. Solid State Chem., 1996, 126, 261 CrossRef CAS.
  17. B. J. Kennedy, J. Solid State Chem., 1995, 119, 254 CrossRef CAS.
  18. B. J. Kennedy, J. Solid State Chem., 1996, 123, 14 CrossRef CAS.
  19. F. Izumi, The Rietveld Method, ed. R. A. Young, Oxford Univ. Press, Oxford, 1993, ch. 13 Search PubMed.
  20. W. R. Busing, K. O. Martin and H. A. Levy, Report ORNL-TM-306, Oak Ridge National Laboratory, Oak Ridge, TN, 1964.
  21. J. N. Reimers, J. E. Greedan and M. Sato, J. Solid State Chem., 1988, 72, 390 CrossRef CAS.
  22. G. Ferey, M. Leblanc and R. De Pape, J. Solid State Chem., 1981, 40, 1 CAS; G. Ferey, M. Leblanc, R. De Pape and J. Pannetier, Solid State Commun., 1985, 53, 559 CrossRef CAS.
  23. M. O'Keeffe, EUTAX, Version 1.3 EMlab Software, Phoenix, AZ, 1993.
  24. G. R. Facer, M. M. Elcombe and B. J. Kennedy, Aust. J. Chem., 1993, 46, 1897 CAS.
  25. R. A. Beyerlein, H. S. Horowitz, J. M. Longo, M. E. Leonowicz, J. D. Jorgensen and F. J. Rotella, J. Solid State Chem., 1984, 51, 253 CAS.
Click here to see how this site uses Cookies. View our privacy policy here.