INFLUENCE OF VANADIUM OXIDE ON THE STRUCTURE AND PROPERTIES OF SILICATE GLASSES MODIFIED BY ZINC OXIDE

Different glasses of the system xV2O5-(40-x) SiO2-40 ZnO-30 P2O5 (x = 0, 5, 15, 25 V2O5 mol%) were prepared by the normal quenching technique. The amorphous character of the as-prepared glasses was verified using X-ray diffraction (XRD) spectroscopy. It implies that V2O5 has no influence on the nature of the well-formed amorphous species. On the other hand, the thermal heat treatment at 480celcius for 12 hours produced some crystalline phases in the host glass network. Modification with zinc and vanadium oxides is totally different from that with alkali oxides. Both ZnO and V2O5 would be entered as intermediate oxides, resulting in the formation of nonbridging oxygen atoms (NBO). However, small amounts of V2O5 and ZnO can be consumed as glass formers to form VO4 and ZnO4 tetrahedral units. Both the structural factors R = V2O5/SiO2 and K = SiO2/ZnO have direct impacts on the material properties. Increasing R and decreasing K led to increasing NBO in the glass network, which decreased both the hardness number (Hv) and glass transition temperature (Tg). The NBO has a high potential to crystallize some particular vanadium silicate aggregated species when the samples are thermally treated at 480OC for 12 hours. Nano crystalline cluster species were identified using transmission electron microscopy (TEM). The replacement of SiO2 with V2O5 enhanced the content and size of well-formed nano-sized clusters.