Effect of high pressure and high temperature on the Na2O · 2CaO · 3SiO2 glass-ceramic’s structural properties

Crystallization in a soda–lime‐silicate glass after high pressure

“…As U is directly related to the diffusion coefficient in the material, 38 it can be said that the processing acted as an energy barrier for diffusion. This result is similar to previous works, where it was shown that in situ crystallization decreases the crystallite sizes when higher pressure values are used 11 …”

“…As it was observed in the low and intermediate frequency region, no significant shifts were observed in the high‐frequency region, indicating no changes in the SiO 4 bonds caused by the HP processing. The analysis of the Raman spectra indicates that vibrational modes of all samples are the same, as also observed when the glass was crystallized in situ, where the vibrational modes present after crystallizations were independent of pressure 11 ; therefore, the cause of N V ′s decrease cannot be associated with any changes in the vibrational modes.…”

“…In situ Raman spectroscopy in pressures up to 19 GPa has shown that HP causes a reduction in inter‐tetrahedral angles 10 as well as the enhancement of Q 2 units at the expense of Q 3 units 10,25 . In a previous work with large volume samples, after in situ crystallization with pressures up to 7.7 GPa, it was observed that the population of Q 2 units increased at the cost of the other Q n units, indicating that the same structure, chain or ring (cyclo) silicate systems, was obtained, and that this structure is highly stable under HP 11 …”

“…The high‐frequency region (800–1200 cm −1 ) is associated with the tetrahedral silica bonds, Q n . This region was deconvoluted in the Q 0 (≈861 cm −1 ), Q 1 (≈917 cm −1 ), Q 2 (≈975 cm −1 ), Q 3 (≈1059 cm −1 ), and BO (≈1028 cm −1 ) bonds, as Q 4 is not observed on this glass 11,24 . Table 2 shows a summary of all fits executed in this deconvolution.…”

In Situ High-Temperature Raman Spectroscopy via a Remote Fiber-Optic Raman Probe

“…Second, the increase in Q 2 bonding observed after heat treatment was at the expense of the decrease in all other Q n bonds, suggesting that the crystalline phase is a ring silicate. This conclusion is confirmed by previous studies on quenched and cooled samples [26], [27].…”