Nguyen Thu Nhan, Mai Thi Lan

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Liquid Na2O-4SiO2 has been constructed by molecular dynamics simulation at 1873 K, ambient pressure under periodic boundary conditions. To clarify the local environment of atoms we apply the oxygen simplex (OS) which is characterized by the size, forming oxygen atom types and the number of sodium located inside the OS. The simulation shows that the liquid comprises the Si-O network and sodium atoms are distributed through different type OSs forming by four O atoms. The number of sodium in particular simplex depends on the size and types of OS. There are five types of OS corresponding to values of n=0÷4. Here n is number of bridge oxygens which an OS passed through. We also found that numerous OSs connected to each other form a long channel where hundreds sodium atoms move. The observed distribution of sodium through Si-O network clearly indicates the structural and dynamics heterogeneity in sodium silicate liquid. 

Keywords: Simulation, oxygen simplex, sodium silicate, structural heterogeneity.


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