A band correlated to Si–O–Si/O–Si–O bending modes is also located at about 475 cm1. The spectra also exhibited two significant bands at about 530 and 700 cm1 due to Zr–O–Zr vibrations of ZrO4 structural units. The niobate groups have also exhibited bands due to NbQO, Nb–O–Nb stretching vibrations at 860 and 600 cm1, respectively, in addition
to the band due to the vibrations of NbO6 (n3-mode) structural units (seemed to have merged with Zr–O–Zr vibrational band) at 530 cm1 [24]. The IR spectrum of crystalline V2O5 is expected to exhibit vibrational bands at 970 cm1 (due to V–O stretching of VQO groups), 815 cm1 (due to V–O–V stretchings) and 600 cm1 (due to V–O–V bending vibrations) [25]. The bands observed in the spectra of glass ceramic V1 at 980, 800 cm1 can there be considered as common vibrational modes due to Si–O–V stretchings where as the band at 600 cm1 can be considered as common vibrations due to Nb–O–V chains. As the concentration of V2O5 is increased in the glass ceramics gradually, the bands due to asymmetrical vibrations of silicate and other structural units are observed to grow at the expense of symmetrical bands.