TITLE:
Additive Effects of Rare-Earth Ions in Sodium Aluminoborate Glasses Using 23Na and 27Al Magic Angle Spinning Nuclear Magnetic Resonance
AUTHORS:
Shunichi Kaneko, Yomei Tokuda, Hirokazu Masai
KEYWORDS:
NMR, Aluminoborate, Rare-Earth
JOURNAL NAME:
New Journal of Glass and Ceramics,
Vol.7 No.3,
July
7,
2017
ABSTRACT: We
conducted structural analysis of xNa2O-yY2O3-5B2O3-3Al2O3 and xNa2O-yLa2O3-5B2O3-3Al2O3 glasses
to elucidate the additive effects of rare-earth ions in these sodium
aluminoborate glasses, and investigated the local environment surrounding Na+ in
them by using 23Na and 27Al magic angle
spinningnuclear magnetic resonance (MAS NMR) spectroscopy. The amount of
higher-coordinated Al species ([5]Al and [6]Al)
gradually increased in response to an increase in the ratios of Y2O3 to
Al2O3 and La2O3 to Al2O3 in each type of glass, respectively. Moreover, the difference in the
cation field strength (CFS) between Y3+ and La3+ was
observed to affect the generation of [5]Al and [6]Al,
especially when the amount of these ions in the glasses increased. In addition
to the above, the coordination number of Na+ ions increased
with an increase in the number of rare earth ions, confirmed by comparing
results with NMR spectra of crystalline Na2Al2B2O7.
The latter possibly occurred due to the oxygen concentration on Al[5] and
Al[6]. Finally, it was confirmed that the formation of [5]Al
and [6]Al decreases molar volume in oxide glasses, which might
be partially due to better atomic packing of [5]Al and [6]Al.