Glass Formation and Structure-Property-Composition Relations of the RE2O3-Al2O3-SiO2 (RE=La, Y, Lu, Sc) Systems

• Published in: Journal of the American Ceramic Society 2011-08, Vol.94 (8), p.2429-2435
• Main Authors: Iftekhar, Shahriar, Grins, Jekabs, Gunawidjaja, Philips N, Edén, Mattias
• Format: Article
• Language: English
• Subjects: Cations; Crystallization; Density; Field strength; Glass; Nuclear magnetic resonance; Polyhedrons; Rare earth metals; Scandium
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1551-2916.2011.04548.x

We report the glass‐forming regions of the ternary Lu2O3–Al2O3–SiO2 and Sc2O3–Al2O3–SiO2 systems. The density, molar volume, compactness, Vickers hardness, refractive index, as well as the glass transition (Tg) and crystallization temperature are compared for two series of RE–Al–Si–O (RE=La, Y, Lu, Sc) glasses that display a constant molar ratio nAl/nSi=1.00, whereas nRE/nSi is equal to either 0.62 or 0.94. Several glass properties scale roughly linearly with the cation field strength (CFS) of the rare‐earth (RE3+) ion, except for the Tg values of the Sc‐bearing glasses that are significantly lower than expected. Magic‐angle spinning 29Si and 27Al nuclear magnetic resonance (NMR) reveal enhanced network disorder and increased relative populations of AlO5 and AlO6 polyhedra in the aluminosilicate glasses for increasing RE3+ CFS, but overall similar Si and Al local environments (chemical shifts and quadrupolar couplings) in all samples associated with a constant nRE/nSi ratio, except for unexpectedly shielded 29Si NMR signals observed from the Sc–Al–Si–O glasses.