The structure of Barium-Phospho-Tellurite glasses

Tellurite glasses are of interest for near and mid-IR optical devices due to their favourable physical properties. However, in producing glasses suitable for applications, it is necessary to include a number of different additives to tailor these properties for each particular use. Literature reports indicate that the addition of P2O5 increases the average tellurium-oxygen coordination number in the glass (the only example of coordination numbers higher than 4 in tellurite glasses that we are aware of) while our own studies have shown that the addition of BaO reduces it. We wish to confirm the unusual interaction between TeO2 and P2O5 in a series of binary glasses and investigating the effect of adding an alkaline earth modifier, BaO to this mixed network.