TY - JOUR
T1 - Nano-phase separation and structural ordering in silica-rich mixed network former glasses
AU - Liu, Hao
AU - Youngman, Randall E.
AU - Kapoor, Saurabh
AU - Jensen, Lars Rosgaard
AU - Smedskjær, Morten Mattrup
AU - Yue, Yuanzheng
PY - 2018/5/22
Y1 - 2018/5/22
N2 - We investigate the structure, phase separation, glass transition, and crystallization in a mixed network former glass series, i.e., B
2O
3-Al
2O
3-SiO
2-P
2O
5 glasses with varying SiO
2/B
2O
3 molar ratio. All the studied glasses exhibit two separate glassy phases: droplet phase (G
1) with the size of 50-100 nm and matrix phase (G
2), corresponding to a lower calorimetric glass transition temperature (T
g1) and a higher one (T
g2), respectively. Both T
g values decrease linearly with the substitution of B
2O
3 for SiO
2, but the magnitude of the decrease is larger for T
g1. Based on nuclear magnetic resonance and Raman spectroscopy results, we infer that the G
1 phase is rich in boroxol rings, while the G
2 phase mainly involves the B-O-Si network. Both phases contain BPO
4- and AlPO
4-like units. Ordered domains occur in G
2 upon isothermal and dynamic heating, driven by the structural heterogeneity in the as-prepared glasses. The structural ordering lowers the activation energy of crystal growth, thus promoting partial crystallization of G
2. These findings are useful for understanding glass formation and phase separation in mixed network former oxide systems, and for tailoring their properties.
AB - We investigate the structure, phase separation, glass transition, and crystallization in a mixed network former glass series, i.e., B
2O
3-Al
2O
3-SiO
2-P
2O
5 glasses with varying SiO
2/B
2O
3 molar ratio. All the studied glasses exhibit two separate glassy phases: droplet phase (G
1) with the size of 50-100 nm and matrix phase (G
2), corresponding to a lower calorimetric glass transition temperature (T
g1) and a higher one (T
g2), respectively. Both T
g values decrease linearly with the substitution of B
2O
3 for SiO
2, but the magnitude of the decrease is larger for T
g1. Based on nuclear magnetic resonance and Raman spectroscopy results, we infer that the G
1 phase is rich in boroxol rings, while the G
2 phase mainly involves the B-O-Si network. Both phases contain BPO
4- and AlPO
4-like units. Ordered domains occur in G
2 upon isothermal and dynamic heating, driven by the structural heterogeneity in the as-prepared glasses. The structural ordering lowers the activation energy of crystal growth, thus promoting partial crystallization of G
2. These findings are useful for understanding glass formation and phase separation in mixed network former oxide systems, and for tailoring their properties.
UR - http://www.scopus.com/inward/record.url?scp=85048605389&partnerID=8YFLogxK
U2 - 10.1039/c8cp01728j
DO - 10.1039/c8cp01728j
M3 - Journal article
SN - 1463-9076
VL - 20
SP - 15707
EP - 15717
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 23
ER -