Abstract
The veiled region in Czochralski sapphire has been examined for defects by optical micrography, scanning electron microscopy, electron microprobe analysis and X-ray topography. High optical scattering in the veiled region is found to be due to a large number of cavities. Some dislocation reactions have been observed in the X-ray topographs. High strain fields associated with cavities are also revealed by the topographs indicating that they contain entrapped gas at high pressure. This pressure is three orders of magnitude greater than that predicted from surface tension considerations.
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References
S. O'hara, J. Cryst. Growth 2 (1968) 145.
B. Cockayne, M. Chesswas, and D. B. Gasson, J. Materials Sci. 2 (1967) 7.
W. Class, H. R. Nesor, and G. T. Murrey, Scientific Report No. 2. Contract A.F. 19(628)-4089 Materials Research Corporation Orangburg NY 1965.
D. L. Stephen and W. J. Alford, J. Amer. Ceram. Soc. 47 (1964) 81.
J. M. Lomell and M. L. Kronberg, Conf. Proc. “Direct Observations of Imperfections in Crystals” (St. Louis, 1960) p. 543.
R. F. Belt, J. Amer. Ceram. Soc. 50 (1967) 588.
A. R. Lang, Acta Met. 5 (1957) 358.
W. W. Webb, Conf. Proc. “Direct observations of Imperfections in Crystals” (St. Louis, 1961) p. 588.
W. J. Alford, W. H. Bauer, and R. W. Matolka, Contract AF 19(604)8495 School of Ceramics, Rutgers, The State University, New Brunswick (1966).
R. Scheuplein and P. Gibbs, J. Amer. Ceram. Soc. 43 (1960) 458.
Idem, ibid 45 (1962) 439.
D. J. Barber and H. J. Tighe, Phil. Mag. 14 (1966) 531.
W. T. Read, “Dislocations in Crystals” (McGraw Hill, New York, 1953).
C. A. May and K. H. G. Ashbee, Phil. Mag. 18 (1968) 61.
P. Delavignette and S. Amelniks, J. Nucl. Matls. 5 (1962) 17.
P. D. Bayer and R. E. Cooper, J. Materials Sci. 2 (1967) 301.
M. F. Ashby and L. F. Brown, Phil. Mag. 8 (1963) 1083.
B. Cockayne, D. S. Robertson, and W. Bardsley. Brit. J. Appl. Phys. 15 (1964) 1165.
W. Bardsley and B. Cockayne, Conf. Proc. ICCG (Boston, 1966). Supplement J. Phys. and Chem. Solids (1967) 109.
M. W. Speight, Metal Sci. J. 2 (1968) 73.
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May, C.A., Shah, J.S. Dislocation reactions and cavitation studies in melt-grown sapphire. J Mater Sci 4, 179–187 (1969). https://doi.org/10.1007/BF00550660
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DOI: https://doi.org/10.1007/BF00550660