Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (03): 237-239.doi: 10.3866/PKU.WHXB20040304

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Transport Property Anomalies under High Pressure in Molten Na2O-SiO2 Binary System Studied by Molecular Dynamics Simulation

Shao Jun;Xu Hua;Lu Wen-Cong;Chen Nian-Yi   

  1. Department of Chemistry, Shanghai University, Shanghai 200436;Department of Chemistry, Arizona State University AZ85027,USA;Department of Chemistry, Changshu Institute of Technology, Changshu 215500
  • Received:2003-07-28 Revised:2003-10-21 Published:2004-03-15
  • Contact: Xu Hua

Abstract: A series of ion dynamics simulations on Na2O-SiO2 binary system at 6000 K ranging from 0 to 100 GPa pressure have been carried out. These systems include SiO2, Na2O•10SiO2,Na2O•5SiO2, Na2O•2SiO2, Na2O•SiO2, 2Na2O•SiO2. The simulated results show that there exists anomalous pressure dependence for oxygen component diffusion coefficient in SiO2, Na2O•10SiO2, Na2O•5SiO2, Na2O•2SiO2 systems. Besides SiO2 system, others have not been reported earlier. In Na2O•10SiO2, Na2O•5SiO2, Na2O•2SiO2 systems, the silicon component diffusion coefficient also shows anomalous pressure dependence, this result has not been reported earlier.   In these systems at about 20 GPa the diffusion coefficient of oxygen component is larger than that at ambient pressure by more than an order of magnitude. That the pressure-induced peak position of oxygen diffusion coefficient is at about 20 GPa is different from the results reported earlier, which is at about 30 GPa.   It is observed that the diffusivity maximum in SiO2 system corresponds approximately to a prevalence of five-coordination of silicon by oxygen, but the diffusivity maximum in Na2O•10SiO2 system corresponds approximately to a prevalence of six-coordination of silicon by oxygen. The latter has not been reported earlier.

Key words: Molecular dynamics simulation, Na2O-SiO2 binary system, Coordination number of silicon by oxygen, Transport property anomaly, High pressure physics