Fictive temperature of GeO2 glass: Its determination by IR method and its effects on density and refractive index

Laser-induced structural changes in pure GeO2 glasses

“…As the objective is moved away from the sample, the Becke line is moving towards the centre of the modified regions, indicating their higher refractive index compared to the surrounding untreated material. This observation suggests, that the modified regions correspond to densified v-GeO 2 , since the refractive index increases with density in v-GeO 2 [10]. For the closely packed regions (B and C in Fig.…”

“…Fig. 1 shows separately the effect of densification and fictive temperature [10,24] on the Raman spectra of vGeO 2 . The spectrum for the sample densified at 15.4 GPa is very similar to those obtained previously in similar conditions [15].…”

“…Ultra-fast thermal quenching of the micro-explosion site, with cooling rates of ∼ 10 14 Ks − 1 (estimated as the maximum temperature divided by the hydrodynamic time while the matter is moving) [8], should help to retrieve new and metastable phases of shock transformed regions inside dielectrics: glasses and crystals [9]. Apart from a fundamental interest of temperature and pressure effects on the glass structure [1,10,11], the long term behaviour of glasses, subjected to extreme conditions, is important for applications ranging from the construction of solar cell panels and waveguide laser writing to radioactive waste enclosure [12].…”

Brillouin spectroscopy of Nd–Ge co-doped silica fibers

“…Extrapolating the data in Ref. [11], we can estimate that at a fictive temperature of 2000°C (as a limit), the density of pure germania is in the vicinity of 3370 kg/m 3 . Fig.…”

“…However, not only will there be a net reduction in the index of refraction due to an elevated fictive temperature, but the density is also expected to be slightly lower as well [11], modifying the influ- is the mass density, and a is the acoustic attenuation coefficient (m À1 ). m is a volume fraction in a well-mixed glass.…”