Ultrasonic studies on alkali borate tungstate glasses

Longitudinal and shear ultrasonic wave velocities have been measured in different compositions of the glass system 20Li(2)O-(80-x)B(2)O(3-)xWO(3) (0 <= x <= 125mol%), at room temperature and at 4MHz frequency. Elastic moduli, Debye temperature and Poisson's ratio have been obtained as a function of WO(3) content. Based on FTIR spectroscopy and theoretical bond compression model, quantitative analysis has been carried out in order to obtain more information about the structure of these glasses. The longitudinal ultrasonic wave velocity measurements showed a bend at about 2.5 mol% WO(3) content while shear ultrasonic wave velocity decreased monotonously with an increase Of WO(3) content. Elastic moduli values decreased as WO(3) content increased from 0 to 2.5 mol%. Further increase of WO(3) beyond 2.5 mol% increased the elastic moduli values. It is suggested that these behaviours are mainly due to the presence Of WO(3) in the network structure of these glasses as a network modifier when WO(3) content is between 0 and 2.5 mol%, and acts as a network former above 2.5 mol%. (c) 2008 Elsevier Ltd. All rights reserved.