High-pressure transformation of Al2O3

Science

Volumn 278, Issue 5340, 1997, Pages 1109-1111

  Funamori, Nobumasa ^a   Jeanloz, Raymond ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALUMINUM; OXIDE;

P/T CONDITIONS; PHASE TRANSFORMATION; RUBY;

ARTICLE; CONTAMINATION; DECOMPRESSION; PRIORITY JOURNAL; QUANTUM MECHANICS; SHOCK WAVE; X RAY DIFFRACTION;

EID: 0030707652     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.278.5340.1109     Document Type: Article

References (30)

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12. A gasketed Mao-Bell type DAC was used with anvils having 200-μm culets [H. K. Mao, P. M. Bell, K. J. Dunn, R. M. Chrenko, R. C. DeVries, Rev. Sci. Instrum. 50, 1002 (1979)]. The gasket was spring steel, and the sample diameter under pressure was ∼80 μm. The sample was heated by means of a continuous (cw) Nd:YAG (Nd:yttrium-aluminum-garnet) laser operating in multi-mode (wavelength of 1064 nm), as described by A. Kavner and R. Jeanloz [in Advanced Materials '96, M. Akaishi et al., Eds. (NIRIM, Tsukuba, Japan, 1996), pp. 143-147]. The laser beam was focused to a diameter of ∼15 μm and scanned to heat the entire sample. X-ray diffraction patterns were collected in angular-dispersive mode at beamline 10-2 of the Stanford Synchrotron Radiation Laboratory (SSRL), using a monochromatized x-ray beam of 17.038 keV with an imaging-plate detector. Because the diameter of the incident x-ray beam was slightly larger than that of the sample diffraction line or lines from the gasket were present in the patterns we collected. The imaging-plate data were converted to a 2θ-intensity profile, using the program developed by J. H. Nguyen and R. Jeanloz [Rev. Sci. Instrum. 64, 3456 (1993)]. All x-ray diffraction measurements were carried out at room temperature.
13. A gasketed Mao-Bell type DAC was used with anvils having 200-μm culets [H. K. Mao, P. M. Bell, K. J. Dunn, R. M. Chrenko, R. C. DeVries, Rev. Sci. Instrum. 50, 1002 (1979)]. The gasket was spring steel, and the sample diameter under pressure was ∼80 μm. The sample was heated by means of a continuous (cw) Nd:YAG (Nd:yttrium-aluminum-garnet) laser operating in multi-mode (wavelength of 1064 nm), as described by A. Kavner and R. Jeanloz [in Advanced Materials '96, M. Akaishi et al., Eds. (NIRIM, Tsukuba, Japan, 1996), pp. 143-147]. The laser beam was focused to a diameter of ∼15 μm and scanned to heat the entire sample. X-ray diffraction patterns were collected in angular-dispersive mode at beamline 10-2 of the Stanford Synchrotron Radiation Laboratory (SSRL), using a monochromatized x-ray beam of 17.038 keV with an imaging-plate detector. Because the diameter of the incident x-ray beam was slightly larger than that of the sample diffraction line or lines from the gasket were present in the patterns we collected. The imaging-plate data were converted to a 2θ-intensity profile, using the program developed by J. H. Nguyen and R. Jeanloz [Rev. Sci. Instrum. 64, 3456 (1993)]. All x-ray diffraction measurements were carried out at room temperature.
14. A gasketed Mao-Bell type DAC was used with anvils having 200-μm culets [H. K. Mao, P. M. Bell, K. J. Dunn, R. M. Chrenko, R. C. DeVries, Rev. Sci. Instrum. 50, 1002 (1979)]. The gasket was spring steel, and the sample diameter under pressure was ∼80 μm. The sample was heated by means of a continuous (cw) Nd:YAG (Nd:yttrium-aluminum-garnet) laser operating in multi-mode (wavelength of 1064 nm), as described by A. Kavner and R. Jeanloz [in Advanced Materials '96, M. Akaishi et al., Eds. (NIRIM, Tsukuba, Japan, 1996), pp. 143-147]. The laser beam was focused to a diameter of ∼15 μm and scanned to heat the entire sample. X-ray diffraction patterns were collected in angular-dispersive mode at beamline 10-2 of the Stanford Synchrotron Radiation Laboratory (SSRL), using a monochromatized x-ray beam of 17.038 keV with an imaging-plate detector. Because the diameter of the incident x-ray beam was slightly larger than that of the sample diffraction line or lines from the gasket were present in the patterns we collected. The imaging-plate data were converted to a 2θ-intensity profile, using the program developed by J. H. Nguyen and R. Jeanloz [Rev. Sci. Instrum. 64, 3456 (1993)]. All x-ray diffraction measurements were carried out at room temperature.
15. See, for example, W. A. Caldwell et al., Science 277, 930 (1997).
16. Because the equation of state of Pt is well known, pressure can be calculated from the unit-cell volume of Pt measured by x-ray diffraction [N. C. Holmes, J. A. Moriarty, G. R. Gathers, W. J. Nellis, J. Appl. Phys. 66, 2962 (1989)].
17. See for example, D. Heinz and R. Jeanloz, J. Geophys. Res. 92, 11437 (1987).
18. 3.
19. (2) = (0.000, 0.049, 0.250) (7).
20. R. J. Hemley et al., Science 276, 1242 (1997). Because we did not heat the gasket, it may have retained a large uniaxial stress.
21. 3 (II) phase when ruby is heated at a pressure as low as ∼85 GPa.
22. To avoid such problems in ultra-high pressure experiments with the laser-heated DAC, attempts are usually made to obtain ruby-fluorescence determinations of pressure from portions of the sample that have been heated as little as possible. See E. Knittle and R. Jeanloz, Science 235, 668 (1987); Q. Williams, E. Knittle, R. Jeanloz, J. Geophys. Res. 96, 2171 (1991); (3); and (7).
23. To avoid such problems in ultra-high pressure experiments with the laser-heated DAC, attempts are usually made to obtain ruby-fluorescence determinations of pressure from portions of the sample that have been heated as little as possible. See E. Knittle and R. Jeanloz, Science 235, 668 (1987); Q. Williams, E. Knittle, R. Jeanloz, J. Geophys. Res. 96, 2171 (1991); (3); and (7).
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26. 3 at pressures above 100 GPa.
27. 3 at pressures above 100 GPa.
28. S. P. Marsh, Ed., LASL Shock Hugoniot Data (Univ. of California Press, Berkeley, CA, 1980).
29. A. P. Jephcoat, H. K. Mao, P. M. Bell, J. Geophys. Res. 91, 4677 (1986).
30. We are grateful to M. S. T. Bukowinski, T. Uchida, J. H. Nguyen, W. A. Caldwell, L. R. Benedetti, and staff members at SSRL for helpful discussions and experimental support. Supported by NSF, NASA, and the Miller Institute for Basic Research in Science (Berkeley, CA).