Infrared and Raman Spectroscopic Studies on mixed alkali tungsten based glasses

Quaternary tungstate glasses containing K2O, Na2O and B2O3 have been prepared by melt quench technique and studied by IR and Raman spectroscopy. Raman and infrared spectroscopy have been employed to investigate the (30−x)Na2O–xK2O–10WO3–60B2O 3 glasses in order to obtain information about the competitive role of WO3 and B2O3 in the formation of glass network. IR spectral study reveals the existence of BO3 and BO4 groups with W-O-W vibrations in the present glasses. Raman scattering study of the present system to understand the role of the mass of the cation in determining the B-O network in glasses. Raman results show that lighter cations favour a stronger B-O network in which three-dimensional BO4 groups are attached to a large borate ring while the heavy cations are not easily inserted in the network interstices. The introduction of heavy cations favours the formation of non-bridging oxygens which make the B-O network comparatively weak. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO3 and BO4 units placed in different structural groups, the BO3 units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition. Keywords– Amorphous, Borate glasses, FTIR, Melt quenching, Mixed alkali effect, Raman scattering, X-ray diffraction. ——————————  ——————————