Zinc Borophosphate Glasses Doped with Molybdenum Oxide

The glasses of the series (1-x)[0.5ZnO-0.1B2O3-0.4P2O5]-xMoO3 with 0 ≤ x ≤ 0.6 were prepared by slow cooling of the melt. These glasses were characterized by the measurements of density, molar volume, chemical durability, glass transition temperature and the thermal expansion coefficient. The density and molar volume of the glasses increase with increasing MoO3 content. All glasses crystallize on heating and their crystallization temperature decreases with increasing MoO3 content. An incorporation of MoO3 into the parent borophosphate glass results in a substantial decrease of their glass transition temperature and also of their chemical durability. The observed changes were ascribed to the gradual replacement of stronger P-O-P bonds by weaker Mo- O-P and Mo-O-Mo bonds. ESR spectra revealed the presence of Mo5+ ions responsible for the blue colour of the glasses and the relative ratio of Mo5+/Mototal decreases with increasing MoO3 content.