Principal Vibration Modes of the La₂O₃–Ga₂O₃ Binary Glass Originated from Diverse Coordination Environments of Oxygen Atoms

Abstract

La 2 O 3 −Ga 2 O 3 binary glass exhibits unusual optical properties owing to its high oxygen polarizability and low vibration energy. These optical properties include high refractive indices and a wide transmittance range. In this study, we performed classical molecular dynamics simulations on La 2 O 3 −Ga 2 O 3 glass synthesized by an aerodynamic levitation technique. We have obtained structural models that reproduce experimental results, such as NMR, high-energy X-ray diffraction, and neutron diffraction. Based on our analysis, the structural features were clarified: 5-, 6-coordinated Ga, edge-sharing GaO x −GaO x polyhedral linkages, and oxygen triclusters. Additionally, the vibrational density of states was calculated by diagonalization of the dynamical matrix derived from the structural models and the results were compared with Raman scattering spectra. The mode analysis of the Raman spectra revealed that the principal bands at 650 cm −1 were mainly attributed to the stretching modes of the bridging and nonbridging oxygens. Meanwhile, the shoulder bands at the highest frequency of 750 cm −1 were mainly attributed to the stretching modes of the bridging oxygens and oxygen triclusters. The structural models obtained in this study well describe the characteristic local structures and vibrational properties of the La 2 O 3 −Ga 2 O 3 glass.

Modeling Oxygen Tricluster Formation in Calcium Aluminosilicate Supercooled Liquids and Glasses

“…A study done by Khanna et al suggests the possibility of tricluster formation in phospho-borosilicate glasses. It has also been proposed that oxygen triclusters act as charge compensating agents in La 2 O 3 –Ga 2 O 3 binary glasses . More research should be done to determine whether 3Si–0Al tricluster types reside in pure silica glass.…”

“…It has also been proposed that oxygen triclusters act as charge compensating agents in La 2 O 3 −Ga 2 O 3 binary glasses. 27 More research should be done to determine whether 3Si−0Al tricluster types reside in pure silica glass. Figure 3a−d shows that the fractions of these various tricluster types depend on silica content.…”

Gallosilicate glass and fiber for radiation detection

“…11,12 The Raman band at 850-1100 cm −1 is attributed to Si- O stretching mode associated with Si-O-Ga or Si-O-Si bridges. 13,14 In addition, a weak broad-shoulder signal below 430 cm −1 is ascribed to La-O-related vibrations. 15 The Raman spectra show no obvious change with different durations of UV light, indicating that high-energy irradiation does not induce changes in the chemical bonding structure of the glasses.…”

Glass forming regions, structure and properties of lanthanum barium germanate and gallate glasses

“…This effect is clearly visible in the infrared spectra showing that the asymmetric stretching of germanium units with non-bridging oxygens vibrating above 800 cm -1 decreases in magnitude when the germanium oxide content decreases and shifts from 825 cm -1 for Ge-68 to reach 760 cm -1 for the composition Ge-40. In the case of pure gallate sample (Ge-0), the contribution around  760 cm -1 could be related to ν (Ga-O -Ga) stretching mode [41], [42]. In this gallate glass composition, new contributions are observed around  630 cm -1 and  690 cm -1 in the Raman and IR spectra respectively which increases upon the addition of gallium oxide content.…”

“…In this gallate glass composition, new contributions are observed around  630 cm -1 and  690 cm -1 in the Raman and IR spectra respectively which increases upon the addition of gallium oxide content. Yoshimoto et al in binary lanthanum-gallate glasses have assigned the Raman band at around 630 cm -1 to ν (Ga [4,5,6] -O) stretching vibration arising from either gallium polyhedra (GaOx)4  x  6 with possibly non-bridging oxygens (NBOs) or gallate tri-clusters (Ga [4] -O [3] ) [41]. The key points for understanding the germanogallate glass structures and properties rely on the investigation of the charge compensation mechanism of charged gallate units, in particular the [GaO4]units and the formation of either by Qi = 1, 2, 3, 4 germanate or gallate units.…”