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A29Si NMR study of natural and synthetic melanophlogites, the silica analogues of the clathrate hydrates of type I


29Si MAS NMR spectra of natural melanophlogite as well as of synthetic melanophlogite indicate that the room temperature lattice structure has lower symmetry than expected from its proposed crystal structure. On heating the samples to temperatures above room temperature, the structure undergoes a reversible phase transition with a transition temperature characteristic of the locality. For the synthetic melanophlogite, the transition is over the range 298 K to 338 K. From low temperature NMR spectra it is concluded that the low temperature forms of synthetic melanophlogite and of melanophlogite from Sicily differ in their crystal lattice symmetries due to their characteristic guest species.

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  1. 1.

    A. L. Lasaulx:N. Jb. Miner. 1876, 250 (1876).

  2. 2.

    B. J. Skinner and D. E. Appleman:Am. Miner. 48, 854 (1963).

  3. 3.

    M. Grasselini Troyisi and P. Orlandi:Atti Soc. Tosc. Sci. Nat., Mem., Serie A 79, 245 (1972).

  4. 4.

    L. Zák:Am. Miner. 57, 779 (1972).

  5. 5.

    J. R. Cooper, J. F. Dunning:Am Miner. 57, 1494 (1972).

  6. 6.

    S. K. Kropatsheva and J. J. Makarov:Dokl. Akad. Nauk USSR 224, 905 (1975).

  7. 7.

    B. Kamb:Science 148, 232 (1965).

  8. 8.

    H. Gies:Z. Kristallogr. 164, 247 (1983).

  9. 9.

    M. V. Stackelberg and H. R. Müller:Z. Elektrochem. 58, 25 (1954).

  10. 10.

    H. Gies, H. Gerke and F. Liebau:N. Jb. Miner Mh. 3, 119 (1982).

  11. 11. (a)

    E. R. Andrew, A. Bradbury and R. G. Eades:Nature 182, 1659 (1958). (b) I. J. Lowe:Phys. Rev. Lett. 2, (1959).

  12. 12.

    J. Schaefer and E. O. Stejskal:J. Am. Chem. Soc. 98, 1031 (1976).

  13. 13.

    J. S. Frye and G. E. Maciel:J. Magn. Reson. 48, 125 (1982).

  14. 14.

    A. Pines, M. G. Gibby and J. S. Waugh:J. Chem. Phys. 56, 177C (1972).

  15. 15.

    M. J. Buerger: inPhase Transformations in Solids, ed. R. Smoluchowski, J. Wiley, New York, 1957.

  16. 16.

    J. V. Smith and C. S. Blackwell:Nature 303, 223 (1983).

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Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena.

On leave Mineralogisches Institut, CAU KIEL, FRG

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Fyfe, C.A., Gies, H. A29Si NMR study of natural and synthetic melanophlogites, the silica analogues of the clathrate hydrates of type I. J Incl Phenom Macrocycl Chem 8, 235–239 (1990).

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Key words

  • Melanophlogite
  • 29Si NMR
  • phase transition