Dependence of Gd2O3 containing silicate glass workability and fragility on structure

In order to explore the effect of Gd2O3 on the workability and kinetic fragility of soda lime silicate glass, the working range (between working point and softening point) and kinetic fragility index of Gd2O3 free and doped soda lime silicate glass were calculated by using of Vogel-Fulcher-Tammann (VET) equation and expressed by the steepnees index values at glass transition respectively. And the influence of Gd2O3 on soda lime silicate glass structure were also studied by FTIR and Raman spectroscopy to elucidate the effect of Gd2O3 on the workability and fragility of soda lime silicate glass. The results show that the addition of Gd2O3 into soda lime silicate glass shortens the working range from 343 degrees C to 309 degrees C, and increase the kinetic fragility index from 41 to 44 resulted from the increase in the slope (d eta/dT or dlog eta/dT) of viscosity of soda lime silicate glass with temperature. The band position assigned to Si-O-Si asymmetric stretching vibration in FTIR spectra of soda lime silicate glass shift from 1080 cm(-1) to 1060 cm(-1), while doping of Gd2O3 leads to shift from 1090 cm(-1) to 1050 cm(-1) as the temperature elevates from 1250 to 1550 degrees C. Results of Raman spectra indicates the doping of Gd2O3 induce the different conversion of basic structural units Q(n) in silicate melt to occur, consequently the average numbers of oxygen and NBO per [SiO4] tetrahedron increase from 2.70 and 1.40 to 2.73 and 1.47, and the average number of bridging corners per tetrahedron decrease from 2.60 to 2.53 at 1550 degrees C. Therefore, the effect of Gd2O3 on the workability and fragility of soda lime silicate glass can be attributed to the variation of corresponding melt structure. (C) 2016 Elsevier B.V. All rights reserved.