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Volumn 288, Issue 5471, 2000, Pages 1632-1634

A monoclinic pst-stishovite polymorph of silica in the Shergotty meteorite

Author keywords

[No Author keywords available]

Indexed keywords

SILICON DIOXIDE;

EID: 0034595876     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.288.5471.1632     Document Type: Article
Times cited : (108)

References (34)
  • 1
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    • S. K. Saxena et al., Science 274, 1357 (1996)
    • (1996) Science , vol.274 , pp. 1357
    • Saxena, S.K.1
  • 6
    • 2342558101 scopus 로고
    • Wiley & Sons, New York
    • _ and P. H. Abelson, Eds., Research in Geochemistry (Wiley & Sons, New York, 1967), vol. 2, p. 204.
    • (1967) Research in Geochemistry , vol.2 , pp. 204
    • Abelson, P.H.1
  • 15
    • 0342540500 scopus 로고    scopus 로고
    • in preparation
    • L. S. Dubrovinsky and S. K. Saxena, Phys. Rev. Letters, in preparation; Phys. Chem. Minerals, in preparation.
    • Phys. Chem. Minerals
  • 23
    • 0343410101 scopus 로고    scopus 로고
    • note
    • 3) at each position of the detector.
  • 24
    • 0342974783 scopus 로고    scopus 로고
    • note
    • The sample disc was mounted on a 0.8-mm hole in a larger steel disc that was loaded onto the goniometer stage for the x-ray studies.
  • 25
    • 0343846041 scopus 로고    scopus 로고
    • note
    • The sample was first scanned with 25-μm mesh to identify the major phases in the sample.
  • 27
    • 0342974782 scopus 로고    scopus 로고
    • note
    • Within the 420-μm-long and 80-μm-wide silica grain, four distinct points were investigated and no distinguishable differences have been found. To partially overcome the problems of preferred orientation and make the relative intensities of the reflections more representative of a powder x-ray pattern, the sample plate was rotated on 30° from the initial position normal to x-ray beam with a step of 1° in w-axis during data collection. Positions of the lines obtained as the average over all collected spectra. The position of the finely collimated x-ray beam penetrating through the silica grain was continuously monitored on a screen with a CCD camera. We made efforts to include smooth areas as shown in Fig. 1B within the four areas irradiated by the x-ray beam.
  • 30
    • 0343410098 scopus 로고    scopus 로고
    • note
    • 2, we milled the ions with a liquid-nitrogen cooled sample holder and with a 4-kV accelerating potential The sample was lightly coated with amorphous carbon to prevent charging in the electron beam. Samples were investigated with a Philips CM200-FEC (FEI Co., Eindhoven, Netherlands), a 200 kV microscope equipped with a field emission gun (FEG). To minimize irradiation damage during characterization, we collected data on a slow-scan CCD camera while using low electron doses.
  • 34
    • 0343410097 scopus 로고    scopus 로고
    • note
    • M.C. is supported by National Science Foundation of China (grant 49825132) and a Deutsche Forschungsgemeinschaft (grant Go 315/15-1). Two anonymous reviewers helped in substantially improving the manuscript.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.