Structural relaxation and quasi-elastic light scattering in glass: Approach by ferroelectric and ion-conducting phases

Abstract

Inelastic light scattering has been utilized for examining the structure of glass and its relaxation. However, the quasi-elastic-light-scattering (QLS) phenomenon has not been addressed in much detail. In this study, we observed pronounced QLS-intensity variations in two temperature domains—supercooled liquid (SCL) state (α-relaxation regime) and below the glass-transition temperature (β-relaxation regime)—in niobium-oxide (Nb2O5)-rich glass. These variations may be interpreted on the basis of the concept of ferroelectric and ion-conducting phases. It was suggested that the observed QLS originates as a result of the polarization fluctuation of NbO6 units, which is due to the dynamics of the nanometric phase separation in the SCL phase (α-regime), and the fluctuation due to the migration/hopping of conductible ions that are localized in the vicinity of the NbO6 units (β-regime).

Structural stability of NaPON glass upon heating in air and nitrogen

“…5a. A similar behavior has been observed during in situ high temperature Raman measurements on phosphoniobate glass, in which niobate NbO 6 polyhedra with different degrees of distortions corresponding to two Raman bands exhibit an opposite dependence on temperature in peak intensity, also ascribed to "nanometric phase separation" [48]. The same trend observed here might suggest a similar scenario, in which structural separation at nanoscale takes place within the oxynitride sub-network.…”

Low frequency Raman study of the Boson peak in a Tellurite-tungstate glass over temperature

“…Experimental data available in the literature shows us that BP position usually ranges from ∼ 40cm −1 to ∼ 80cm −1 [19], depending on composition. The BP Temperature dependence have been investigated in Silica [26], Calcium-aluminosilicate [19], Germania [27], Phosphate [28], Borate [29], Tellurite-Zinc [30] and Tellurite-Oxyhalide [31] glasses, and the results agree that increasing temperature red shifts the peak. This last observation does also agree with the "blobs" idea, once that increasing temperature the material is expanding, which is in favor of longer wavelength phonons, i.e.…”

“…In the low energy range of Raman spectra Quasi-elastic light scattering (QES) may also be expected [23,24,25,26,27,28,29] at this low energy range. In liquids the QES originates from the Doppler shift of the light reflected by one moving particle with speed v relative to the detector, and this phenomena is the basis of a few experimental techniques, such as laser doppler velocimetry.…”

“…In liquids the QES originates from the Doppler shift of the light reflected by one moving particle with speed v relative to the detector, and this phenomena is the basis of a few experimental techniques, such as laser doppler velocimetry. In solids however, the QES origin is still on debate [26] and it seems to be a concensus that this band is centered at 0cm −1 and may extent until ∼ 50cm −1 [28] in glasses. Experimental data available in the literature shows us that BP position usually ranges from ∼ 40cm −1 to ∼ 80cm −1 [19], depending on composition.…”

Multiferroic BiFeO3 glass-ceramics: Phase formation and physical property

“…2,3 Therefore, the processing has been studied intensively in order to produce the sophisticated functional materials, e.g., X-ray imaging plate, Pb-free nanoferroelectrics, and solid oxide fuel cell. [4][5][6] Recently, multiferroic material has absorbed much attentions because it enable us to develop the advanced device based on magnetoelectric (ME) effect: Perovskite-type BiFeO 3 (BFO) possesses both ferroelectric and antiferromagnetic properties, which appear above room temperature (Curie temperature: T c $ 827 C; N eel temperature: T N $ 367 C). 7 Furthermore, since BFO also shows photovoltaic and photocatalytic properties, 8,9 the BFO is expected to be used in various applications.…”