article posted 22 March 2016
I am currently doing my PhD at the Otto-Schott-Institute of Materials Research in Jena, Germany. Among other things, I am dealing in my thesis with the structure of metaphosphate glasses. I received my diploma in chemistry from the same university in 2009. I spent almost two years at the j-fiber GmbH in Jena, working in the section for preform production.
Structure and properties of mixed divalent metaphosphate glasses and the mixed cation effect
K. Griebenow*1, D. Möncke1, E.I. Kamitsos2, L. Wondraczek1
1Otto-Schott-Institute of Materials Research, Friedrich-Schiller University Jena, Fraunhoferstr. 6, 07743 Jena, Germany
2Theoretical & Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
In this work we investigate the influence of the mixed cation effect (MCE) on the mechanical and physical properties of alkaline earth and transition metal metaphosphate glasses, (M/N)O-P2
with M=Sr (Mg, Ba), N=Mg, Ca, Sr, Ba, Mn, Co.
It was found that the compositional dependence of physical and mechanical properties is strongly influenced by the pairing of the cations. The nonlinear trend is more pronounced when the cation radii of the modifier oxides show the largest difference, for example when mixing Sr and Mg rather than Sr and Ba.
The structure of the glasses was analysed with NMR, Raman and FTIR spectroscopy.
For the Mg-Sr and the Sr-Ba series the shift of the Raman signal assigned to the symmetric stretching vibration of PO2-
terminal groups in Q2
units at ~1200 cm-1
is illustrated in Figure 1. An almost linear trend is seen for the Sr-Ba mixing and a nonlinear band shift for the Mg-Sr series. It is suggested that the mixed cations may not be randomly distributed in the network.
Figure 1. Compositional dependence of the band shift of the symmetric stretching vibrations of PO2-
units observed in the Raman spectra of mixed cation glasses.