The structure of SiO2–GeO2 glasses: A spectroscopic study

Dependence of the emission properties of the germanium lone pair center on Ge doping of silica

“…In figure 7, we report [10], it can be concluded that the vibration mode associated to the D 1 band is not connected to this process. However, it can be guessed that for high Ge concentration, when the Ge distances are below 2 nm, the presence of Ge prevents the formation of the four member rings, as previously suggested [21,23], also introducing modifications in the matrix. On these bases, it can be suggested that the presence of large concentrations of Ge also affects the S 1 -T 1 coupling, so modifying the K ISC rate.…”

“…Taking into account the data in figure 4 and the above considerations, we can conclude that the GLPC optical proprieties are mainly affected by the local environment, within a sphere of radius of ~ 2 nm. Considering this structural effect, it is known that increasing the Ge doping content the Raman spectra of the silica change as a consequence of matrix modifications [21][22][23]. One of the Raman spectral features that can be used to investigate the Ge content effects on the silica glass matrix is the D1 band, peaked at about 490 cm -1 .…”

Atomic structure of a metal-supported two-dimensional germania film

“…There is a discussion in the literature that germania in comparison to silica will have different properties, in particular with respect to the formation of vitreous, i.e., glassy, phases [5][6][7]. Also, doping of germanium into silica or a mixed phase of both might lead to promising materials in a number of applications [8][9][10][11]. Given the detailed information derived from thin-film studies for silica, it is likely that one will be able to reveal the network structures for germania and germania-silica mixtures at the atomic level.…”

The structure of GeO2–SiO2 glasses and melts: A Raman spectroscopy study

“…The principle differences between the two oxide glasses is that GeO 2 glass has a narrower distribution of T-O-T (T = Ge or Si) angles ($132°versus $148-151°), longer T-O bonds (1.74 versus 1.61 Å), and appears to contain significantly more small 3-membered tetrahedral rings (cf., [3,4,7]). Recently, there has been growing interest in glasses along the SiO 2 -GeO 2 join (cf., [8,9]) due to their photonic properties [10], as well as, their potential for polyamorphic transformations [11][12][13][14]. Majérus et al [8] found that with increasing pressure, Ge in SiO 2 -GeO 2 glasses changes coordination from 4-to 6-fold, with the transformation occurring over larger pressure ranges when the SiO 2 content increases.…”

“…They inferred the presence of polyamorphism based on the pressure-composition domains in which Ge was predominantly 4-fold, mixed 4-and 6-fold, and 6-fold coordinated. More recently, they have reinvestigated these glasses at low temperature using Ge K-edge EXAFS and Raman spectroscopy [9]. Their results indicate mixing of the GeO 4 and SiO 4 tetrahedra in a continuous random interconnected network.…”