Molecular dynamics simulation of Eu3+-doped chlorofluorozirconate glasses

Molecular dynamics simulations are performed for ZrF 4 -BaF 2 -EuF 3 glass systems in which 0, 5 and 10% F - ions are substituted by Cl - ions. Changes in local structures of the glasses around each cation are investigated in terms of increasing amount of substitutions of Cl - for F - . The average coordination number of F - around Zr 4+ is found to be approximately 7.7 and is independent of the amount of Cl - substitution. The power spectra of the velocity autocorrelation functions are also calculated. The Zr-F stretching mode observed at around 800 cm -1 shows no shift with Cl - substitution. These results show that the local structure around Zr 4+ is not greatly affected by the small amount of Cl - substitution. The F - coordination number around Eu 3+ at a radius of 3.0 AA and that around Ba 2+ at a radius of 3.5 AA are found to decrease from 8.0 to 5.6 and from 9.2 to 5.1, respectively, as the Cl - fraction increases. This means that Cl - ions substituted for F - exist almost around the Eu 3+ or Ba 2+ cation. Thus, even the small amount of Cl - substitution greatly changes the local structures about Eu 3+ and Ba 2+ .