Raman spectrum of pressure compacted fused silica

Abstract

Raman spectra of compacted fused silica are presented. Fused silica was sujected to a pressure of 9.0 GPa for 1 hr at 23 °C. The density of the compacted silica was 2.40 g cm−3 compared to 2.22 g cm−3 for the uncompacted glass. Various interesting features of the spectrum are discussed. (AIP)

Raman and XANES spectroscopy of permanently densified vitreous silica

“…The spectrum of the undensified glass (top of Fig. 2) is consistent with those of many previous studies [3][4][5][6][7][8][9], with a strong broad band near 430 cm À1 , narrow 'defect' bands at 490 and 600 cm À1 , a broad asymmetric band near 800 cm À1 and two weak bands in the high-frequency region near 1060 and 1190 cm À1 . With increasing densification, most apparent is the behavior of the broad band centered near 430 cm À1 , which becomes narrower and shifts to higher frequencies with increasing density.…”

“…This behavior is similar to that observed by McMillan et al [6], who densified SiO 2 glass at 4 GPa and 530°C. In contrast to these hightemperature experiments, glasses compressed up to about 8 GPa at room temperature and later recovered at ambient pressure exhibit negligible changes in their Raman spectra [4,7,9]. While comparable changes in permanent densification can still be achieved at room temperature, the lack of effect on the sensitive angle bending region of the Raman spectrum suggests that densification at lower temperatures is manifested in medium-range structural features rather than shortrange features such as Si-O bond lengths and Si-O-Si bond angles.…”

“…A number of structural studies have been conducted using Raman spectroscopy to understand this phenomenon [3][4][5][6][7][8][9]. Walrafen and Krishnan [4] densified SiO 2 glass at room temperature and noted that its Raman spectrum remained relatively unchanged, but this can be explained in part by the lower pressures applied in that study. Studies of permanently densified v-SiO 2 at room temperature have demonstrated changes to the Raman spectrum only after having reached pressures above 8 GPa [7][8][9].…”

Raman Spectra of High‐κ Dielectric Layers Investigated with Micro‐Raman Spectroscopy Comparison with Silicon Dioxide

“…However, the contribution of the crystalline structures is so small that their intensities do not exceed the signal-to-noise ratio [12]. D 1 band has the maximum at about 490 cm −1 in non-densified structure and at about 520 cm −1 in densified structure [6, 12, 14]. This band is placed so close to the one-phonon Si line that it is impossible to recognize it without mathematical analysis of the spectrum.…”

“…The other advantage of this experimental technique is its nondestructive character. Examples of application of Raman spectroscopy for investigation of structural deviations are: analysis of mechanical stress distribution [5] and monitoring structural changes like densification caused by technological processes [6]. …”