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Glass formation in amorphous SiO2 as a percolation phase transition in a system of network defects

  • M. I. Ojovan
Condensed Matter

Abstract

Thermodynamic parameters of defects (presumably, defective SiO molecules) in the network of amorphous SiO2 are obtained by analyzing the viscosity of the melt with the use of the Doremus model. The best agreement between the experimental data on viscosity and the calculations is achieved when the enthalpy and entropy of the defect formation in the amorphous SiO2 network are H d =220 kJ/mol and S d =16.13R, respectively. The analysis of the network defect concentration shows that, above the glass-transition temperature (T g ), the defects form dynamic percolation clusters. This result agrees well with the results of molecular dynamics modeling, which means that the glass transition in amorphous SiO2 can be considered as a percolation phase transition. Below T g , the geometry of the distribution of network defects is Euclidean and has a dimension d=3. Above the glass-transition temperature, the geometry of the network defect distribution is non-Euclidean and has a fractal dimension of d f =2.5. The temperature T g can be calculated from the condition that percolation arises in the defect system. This approach leads to a simple analytic formula for the glass-transition temperature: T g =H d /((S d +1.735R). The calculated value of the glass-transition temperature (1482 K) agrees well with that obtained from the recent measurements of T g for amorphous SiO2 (1475 K).

PACS numbers

61.43.Dq 64.60.Ak 64.70.Pf 66.20.+d 

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References

  1. 1.
    B. I. Shklovskii and A. L. Efros, Electronic Properties of Doped Semiconductors (Nauka, Moscow, 1979; Springer, New York, 1984).Google Scholar
  2. 2.
    M. B. Isichenko, Rev. Mod. Phys. 64, 961 (1992).CrossRefADSMathSciNetGoogle Scholar
  3. 3.
    M. I. Klinger, Phys. Rep. 165, 275 (1988).CrossRefADSGoogle Scholar
  4. 4.
    I. Campbell, P.-O. Mari, A. Alegria, and J. Colmenero, Europhys. News 3/4, 46 (1998).Google Scholar
  5. 5.
    A. G. Hunt, J. Non-Cryst. Solids 274, 93 (2000).CrossRefGoogle Scholar
  6. 6.
    K. Binder, J. Non-Cryst. Solids 274, 332 (2000).CrossRefGoogle Scholar
  7. 7.
    N. N. Medvedev, A. Geider, and W. Brostow, J. Chem. Phys. 93, 8337 (1990).CrossRefADSGoogle Scholar
  8. 8.
    A. V. Evteev, A. T. Kosilov, and E. V. Levchenko, Pis’ma Zh. Éksp. Teor. Fiz. 76, 115 (2002) [JETP Lett. 76, 104 (2002)].Google Scholar
  9. 9.
    R. H. Doremus, J. Appl. Phys. 92, 7619 (2002).CrossRefADSGoogle Scholar
  10. 10.
    M. I. Ozhovan, Pis’ma Zh. Éksp. Teor. Fiz. 79, 97 (2004) [JETP Lett. 79, 85 (2004)].Google Scholar
  11. 11.
    M. I. Ojovan and W. E. Lee, J. Appl. Phys. 95, 3803 (2004).CrossRefADSGoogle Scholar
  12. 12.
    J. W. Haus and K. W. Kehr, Phys. Rep. 150, 263 (1987).CrossRefADSGoogle Scholar
  13. 13.
    G. Urbain, Y. Bottinga, and P. Richet, Geochim. Cosmochim. Acta 46, 1061 (1982).CrossRefADSGoogle Scholar
  14. 14.
    G. Hetherington, K. H. Jack, and J. C. Kennedy, Phys. Chem. Glasses 5, 130 (1964).Google Scholar
  15. 15.
    N. M. Pavlushkin, Fundamentals of Sitalle Technology (Stroiizdat, Moscow, 1979) [in Russian].Google Scholar
  16. 16.
    H. Scher and R. Zallen, J. Chem. Phys. 53, 3759 (1970).CrossRefGoogle Scholar
  17. 17.
    M. I. Ozhovan, Zh. Éksp. Teor. Fiz. 104, 4021 (1993) [JETP 77, 939 (1993)].Google Scholar
  18. 18.
    R. Bruning, J. Non-Cryst. Solids 330, 13 (2003).MathSciNetGoogle Scholar

Copyright information

© MAIK "Nauka/Interperiodica" 2004

Authors and Affiliations

  • M. I. Ojovan
    • 1
  1. 1.Sir Robert Hadfield BuildingUniversity of SheffieldSheffieldUnited Kingdom

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