Refractive index of silica glass: influence of fictive temperature

Density of vitreous silica

“…Results of the present study agree with the contention by Haken, et al [18] that the room temperature densities of vitreous silicas do not exhibit the maxima reported by Bruckner [7][8][9] as a function of T f . Haken, et al studied four silicas, which they indicate were either Type II or III glasses.…”

“…Two other expressions relating the fictive temperature of vitreous silica with the position of the 2260 cm À1 absorption band have recently been published by Haken, et al [18] and by Kakiuchida, et al [20]. While there are small differences among values of T f calculated using each of these expressions, these differences are only significant for T f > 1400°C, which was the upper equilibration temperature used by Agarwal, et al [19].…”

“…Fictive temperatures were varied by simultaneously heat treating several samples of different types of silica on a strip of Pt at known temperatures for times exceeding their relaxation times at that temperature [18,19] and then either quenching the samples in water by dropping the Pt strip directly into a beaker of room temperature water or air cooling the samples by placing the Pt strip on a refractory brick and allowing it to cool freely to room temperature. These samples were 1.5 ± 0.1 mm thick, with masses of 0.2-0.5 g. The effect of sample size was studied by simultaneously heat treating three samples of the same glass of different thickness (1 to 3 mm) at 1500°C, followed by either water quenching or air cooling to room temperature.…”

“…The most unusual findings were reported by Bruckner [5][6][7][8][9], who indicated that the density of vitreous silica passes through a maximum at around 1500°C with increasing T f , in contrast to the conclusions of Douglas and Isard [3]. A recent study by Haken, et al [18] questions the maxima reported by Bruckner on the grounds that T f is not equal to the heat treatment temperature for temperatures exceeding 1300 to 1500°C. All of these studies agree that the density of vitreous silicas decreases with increasing water content, but the amount of this decrease is in question.…”

Structural relaxation of dense crown optical glass and soda-lime-silicate glass via Raman spectroscopy

“…13), 14) Top and bottom surfaces of these samples were mirror-polished. To investigate the relationship between fictive temperature and each property, each sample was kept in the furnace at specific temperature.…”