Electrical conductivity of olivine, wadsleyite, and ringwoodite under upper-mantle conditions

Science

Volumn 280, Issue 5368, 1998, Pages 1415-1418

  Xu, Yousheng ^a   Poe, Brent T ^a   Shankland, Thomas J ^a,b   Rubie, David C ^a  

^a UNIVERSITÄT BAYREUTH   (Germany)

^b LOS ALAMOS NATIONAL LABORATORY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ELECTRICAL CONDUCTIVITY; MANTLE; OLIVINE; RINGWOODITE; WADSLEYITE;

ARTICLE; CONDUCTANCE; CRYSTAL STRUCTURE; ELECTRIC CONDUCTIVITY; IMPEDANCE; PHYSICS; PRIORITY JOURNAL; SPECTROSCOPY;

EID: 0032577377     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.280.5368.1415     Document Type: Article

References (39)

1. T. S. Duffy and D. L. Anderson, J. Geophys. Res. 94, 1895 (1989); T. S. Duffy, C. S. Zha, R. T. Downs, H. K. Mao, R. J. Hemley, Nature 378, 170 (1995).
2. T. S. Duffy and D. L. Anderson, J. Geophys. Res. 94, 1895 (1989); T. S. Duffy, C. S. Zha, R. T. Downs, H. K. Mao, R. J. Hemley, Nature 378, 170 (1995).
3. R. J. Banks, Geophys. J. R. Astron. Soc. 17, 457 (1969) [B69]; K. Bahr, N. Olsen, T. J. Shankland, Geophys. Res. Lett. 20, 2937 (1993) [BOS93-1 and BOS93-2].
4. R. J. Banks, Geophys. J. R. Astron. Soc. 17, 457 (1969) [B69]; K. Bahr, N. Olsen, T. J. Shankland, Geophys. Res. Lett. 20, 2937 (1993) [BOS93-1 and BOS93-2].
5. A. Schultz, Phys. Earth Planet. Inter. 64, 68 (1990); _, R. D. Kurtz, A. D. Chave, A. G. Jones, Geophys. Res. Lett. 20, 2941 (1993) [SKCJ93].
6. A. Schultz, Phys. Earth Planet. Inter. 64, 68 (1990); _, R. D. Kurtz, A. D. Chave, A. G. Jones, Geophys. Res. Lett. 20, 2941 (1993) [SKCJ93].
7. H. F. Petersons and S. Constable, Geophys. Res. Lett. 23, 1461 (1996).
8. A. Duba, H. C. Heard, R. N. Schock, J. Geophys. Res. 79, 1667 (1974); S. Constable, J. Geomagn. Geoelectr. 45, 707 (1993).
9. A. Duba, H. C. Heard, R. N. Schock, J. Geophys. Res. 79, 1667 (1974); S. Constable, J. Geomagn. Geoelectr. 45, 707 (1993).
10. S. Constable and A. Duba, J. Geophys. Res. 95, 6967 (1990); T. J. Shankland and A. G. Duba, Geophys. J. Int. 103, 25 (1990); J. J. Roberts and J. A. Tyburczy, J. Geophys. Res. 96, 16205 (1991); S. Constable, T. J. Shankland, A. Duba, ibid. 97, 3397 (1992); A. Duba and S. Constable, ibid. 98, 11885 (1993) [SO2]; L. M. Hirsch, T. J. Shankland, A. G. Duba, Geophys. J. Int. 114, 36 (1993).
11. S. Constable and A. Duba, J. Geophys. Res. 95, 6967 (1990); T. J. Shankland and A. G. Duba, Geophys. J. Int. 103, 25 (1990); J. J. Roberts and J. A. Tyburczy, J. Geophys. Res. 96, 16205 (1991); S. Constable, T. J. Shankland, A. Duba, ibid. 97, 3397 (1992); A. Duba and S. Constable, ibid. 98, 11885 (1993) [SO2]; L. M. Hirsch, T. J. Shankland, A. G. Duba, Geophys. J. Int. 114, 36 (1993).
12. S. Constable and A. Duba, J. Geophys. Res. 95, 6967 (1990); T. J. Shankland and A. G. Duba, Geophys. J. Int. 103, 25 (1990); J. J. Roberts and J. A. Tyburczy, J. Geophys. Res. 96, 16205 (1991); S. Constable, T. J. Shankland, A. Duba, ibid. 97, 3397 (1992); A. Duba and S. Constable, ibid. 98, 11885 (1993) [SO2]; L. M. Hirsch, T. J. Shankland, A. G. Duba, Geophys. J. Int. 114, 36 (1993).
13. S. Constable and A. Duba, J. Geophys. Res. 95, 6967 (1990); T. J. Shankland and A. G. Duba, Geophys. J. Int. 103, 25 (1990); J. J. Roberts and J. A. Tyburczy, J. Geophys. Res. 96, 16205 (1991); S. Constable, T. J. Shankland, A. Duba, ibid. 97, 3397 (1992); A. Duba and S. Constable, ibid. 98, 11885 (1993) [SO2]; L. M. Hirsch, T. J. Shankland, A. G. Duba, Geophys. J. Int. 114, 36 (1993).
14. S. Constable and A. Duba, J. Geophys. Res. 95, 6967 (1990); T. J. Shankland and A. G. Duba, Geophys. J. Int. 103, 25 (1990); J. J. Roberts and J. A. Tyburczy, J. Geophys. Res. 96, 16205 (1991); S. Constable, T. J. Shankland, A. Duba, ibid. 97, 3397 (1992); A. Duba and S. Constable, ibid. 98, 11885 (1993) [SO2]; L. M. Hirsch, T. J. Shankland, A. G. Duba, Geophys. J. Int. 114, 36 (1993).
15. S. Constable and A. Duba, J. Geophys. Res. 95, 6967 (1990); T. J. Shankland and A. G. Duba, Geophys. J. Int. 103, 25 (1990); J. J. Roberts and J. A. Tyburczy, J. Geophys. Res. 96, 16205 (1991); S. Constable, T. J. Shankland, A. Duba, ibid. 97, 3397 (1992); A. Duba and S. Constable, ibid. 98, 11885 (1993) [SO2]; L. M. Hirsch, T. J. Shankland, A. G. Duba, Geophys. J. Int. 114, 36 (1993).
16. K. Omura, Phys. Earth Planet. Inter. 65, 292 (1991).
17. A. Duba and J. von der Gönna, ibid. 82, 75 (1994); K. Omura, ibid., p. 79.
18. A. Duba and J. von der Gönna, ibid. 82, 75 (1994); K. Omura, ibid., p. 79.
19. 10 thermocouple without correcting the measured electromotive force for effects of pressure.
20. D. C. Rubie, C. R. Ross II, M. R. Carroll, S. C. Elphick, Am. Mineral. 78, 574 (1993); D. Canil, Phys. Earth Planet. Inter. 86, 25 (1994).
21. D. C. Rubie, C. R. Ross II, M. R. Carroll, S. C. Elphick, Am. Mineral. 78, 574 (1993); D. Canil, Phys. Earth Planet. Inter. 86, 25 (1994).
22. Polycrystalline olivine, wadsleyite, and ringwoodite samples were prepared by hot-pressing olivine powder (Mo capsule) in the multi-anvil apparatus for 2.5 hours at 1200°C and 4, 15, and 20 GPa, respectively. After hot-pressing, the samples were prepared as disks about 1.55 mm in diameter and 0.40 mm thick, and the polished faces showed no detectable iron loss. The samples were characterized by x-ray diffraction, electron microprobe analysis, and optical microscopic examination and showed no evidence of minor phases. One single-crystal sample of olivine (a-axis orientation) was also used. After the sample was placed inside the octahedral pressure medium, the whole cell assembly was dried overnight at 225°C in a vacuum furnace. After measurements, microscopic examinations showed no grain size changes, and geometric distortions were small so that they introduced maximum uncertainties of 12%. Mössbauer spectra were acquired for some synthesized specimens.
23. To overcome such high-pressure and high-temperature experimental difficulties as leakage current and electrical disturbance from the furnace, we used a parallel electrode method with a Mo shield connected to ground (Fig. 1). Advantages of the shield include filtering electrical disturbances from the furnace, reducing temperature gradients, reducing leakage current through the pressure medium, and blocking reactions between sample and pressure medium. For impedance spectroscopy, we used a Solartron 1260 impedance-gain phase analyzer with 1 V applied voltage over the frequency range 10 mHz to 1 MHz. This method gives results identical to in-circuit impedance measurements because major leakage current paths in parallel with the sample are excluded by virtual earth guarding through the grounded shield. Thermoelectric measurements were made on separate samples for which two thermocouples were used to measure an imposed thermal gradient.
24. Y. Xu, B. T. Poe, D. C. Rubie, in The Review of High Pressure Science and Technology, Proceedings of JOINT AIRAPT-16 & HPCJ-38, vol. 7, M. Nakahara, Ed. (Japan Society of High-Pressure Science and Technology, Kyoto, Japan, 1998), pp. 1526-1528.
25. C. H. P. Lupis, Chemical Thermodynamics of Materials (North-Holland, New York, 1983), p. 134.
26. R. N. Schock, A. G. Duba, H. C. Heard, H. D. Stromberg, in High Pressure Research, Applications in Geophysics, M. H. Manghnani and S. Akimoto, Eds. (Academic Press, San Diego, CA, 1977), pp. 39-51.
27. Complications in (7) include the following; (i) Leakage paths divert currents through high-conductivity reaction products between the sample and pressure medium (8). (ii) The oxidation state of the sample during the measurement could not be well defined (8). (iii) Iron loss to the electrodes during hot-pressing before the conductivity measurements inhibited current flow through the sample. We also performed one experiment in which wadsleyite was synthesized from olivine and its electrical conductivity measured in the same experiment, a procedure similar to Omura's. This experiment showed a conductivity increase of only a factor of ∼3 at the olivine-wadsleyite transition, which resembles Omura's result (7). Because the sample recovered after this procedure showed severe iron loss to the electrodes from a zone ∼10 μm thick on each side, we rejected the results of this experiment. Analyses of the samples in Fig. 3 showed no iron loss.
28. R. N. Schock, A. G. Duba, T. J. Shankland, J. Geophys. Res. 94, 5829 (1989); S. Constable and J. J. Roberts, Phys. Chem. Miner. 24, 319 (1997).
29. R. N. Schock, A. G. Duba, T. J. Shankland, J. Geophys. Res. 94, 5829 (1989); S. Constable and J. J. Roberts, Phys. Chem. Miner. 24, 319 (1997).
30. H. St. C. O'Neill et al., Am. Mineral. 78, 456 (1993).
31. B. Kamb, ibid. 53, 1439 (1968).
32. G. Nover, G. Will, R. Waitz, Phys. Chem. Miner. 19, 133 (1992).
33. H. Horiuchi, M. Akaoki, H. Sawamoto, in High-Pressure Research in Geophysics, S. Akimoto and M. H. Manghnani, Eds. (Center for Academic Publications, Tokyo, 1982), pp. 391-403.
34. A. E. Ringwood, Composition and Petrology of the Earth's Mantle (McGraw-Hill, New York, 1975), p. 618; T. Irifune and A. E. Ringwood, Earth Planet. Sci. Lett. 86, 365 (1987).
35. A. E. Ringwood, Composition and Petrology of the Earth's Mantle (McGraw-Hill, New York, 1975), p. 618; T. Irifune and A. E. Ringwood, Earth Planet. Sci. Lett. 86, 365 (1987).
36. E. Ito and T. Katsura, Geophys. Res. Lett. 16, 425 (1989).
37. D. L. Turcotte and G. Schubert, Geodynamics: Applications of Continuum Physics to Geological Problems (Wiley, New York, 1982).
38. T. J. Shankland, J. Peyronneau, J.-P. Poirier, Nature 366, 453 (1993) [SPP93].
39. We thank A. G. Duba and H. Xie for discussions and suggestions; H. Fischer, K. Klasinski, H. Küfner, and R. Weigel for technical assistance; and H. Schulze for making the thin sections. D. L. Kohlstedt (University of Minnesota) donated sample materials. Electron microprobe analyses were performed with the assistance of D. Krauße, and C. McCammon and S. Lauterbach did the Mössbauer analyses of the samples. T.J.S. thanks the Alexander von Humboldt Foundation and the Office of Basic Energy Sciences of the U.S. Department of Energy for support.