Structural models for yttrium aluminium borate laser glasses: NMR and EPR studies of the system (Y2O3)0.2–(Al2O3)x–(B2O3)0.8−x

Abstract

The structure of laser glasses in the system (Y(2)O(3))(0.2){(Al(2)O(3))(x))(B(2)O(3))(0.8-x)} (0.15 ≤ x ≤ 0.40) has been investigated by means of (11)B, (27)Al, and (89)Y solid state NMR as well as electron spin echo envelope modulation (ESEEM) of Yb-doped samples. The latter technique has been applied for the first time to an aluminoborate glass system. (11)B magic-angle spinning (MAS)-NMR spectra reveal that, while the majority of the boron atoms are three-coordinated over the entire composition region, the fraction of three-coordinated boron atoms increases significantly with increasing x. Charge balance considerations as well as (11)B NMR lineshape analyses suggest that the dominant borate species are predominantly singly charged metaborate (BO(2/2)O(-)), doubly charged pyroborate (BO(1/2)(O(-))(2)), and (at x = 0.40) triply charged orthoborate groups. As x increases along this series, the average anionic charge per trigonal borate group increases from 1.38 to 2.91. (27)Al MAS-NMR spectra show that the alumina species are present in the coordination states four, five and six, and the fraction of four-coordinated Al increases markedly with increasing x. All of the Al coordination states are in intimate contact with both the three- and the four-coordinate boron species and vice versa, as indicated by (11)B/(27)Al rotational echo double resonance (REDOR) data. These results are consistent with the formation of a homogeneous, non-segregated glass structure. (89)Y solid state NMR spectra show a significant chemical shift trend, reflecting that the second coordination sphere becomes increasingly "aluminate-like" with increasing x. This conclusion is supported by electron spin echo envelope modulation (ESEEM) data of Yb-doped glasses, which indicate that both borate and aluminate species participate in the medium range structure of the rare-earth ions, consistent with a random spatial distribution of the glass components.

Additive Effects of Rare-Earth Ions in Sodium Aluminoborate Glasses Using <sup>23</sup>Na and <sup>27</sup>Al Magic Angle Spinning Nuclear Magnetic Resonance

“…Thus, we estimate the fraction of four-coordinated boron ( [4] B) in this glass system from the literatures. According to the earlier reports [24], 2Y 2 O 3 -5B 2 O 3 -3Al 2 O 3 glass similar composition to our glass contains 12% of [4] B. In the case of 2.5La 2 O 3 -5B 2 O 3 -2.5Al 2 O 3 , the amount of [4] B is about 11% [15].…”

Network Structure and Rare-Earth Ion Local Environments in Fluoride Phosphate Photonic Glasses Studied by Solid-State NMR and Electron Paramagnetic Resonance Spectroscopies

“…4 that can frequently be disentangled by a two-dimensional pulsed EPR technique called hyperfine sublevel correlation spectroscopy (2D-HYSCORE). [25][26][27][28] While some qualitative studies on crystalline and glassy laser host materials have shown the general feasibility of this approach, [29][30][31][32][33] no work on rare-earth doped fluoride phosphate glasses has been reported so far, to the best of our knowledge.…”

Spying with spins on messy materials: 60 Years of glass structure elucidation byNMRspectroscopy

“…The above pulsed EPR methods present a new approach to rare‐earth‐doped luminescent glasses . Figure shows results for a series of 25BaF 2 –25SrF 2 –(30− x )Al(PO 3 ) 3 – x AlF 3 −19.75YF 3 −0.25YbF 3 glasses.…”

“…[79][80][81][82][83][84][85][86] The above pulsed EPR methods present a new approach to rare-earth-doped luminescent glasses. 73,87,88 Figure 15 shows results for a series of 25BaF 2 -25SrF 2 -(30Àx)Al (PO 3 ) 3 -xAlF 3 À19.75YF 3 À0.25YbF 3 glasses. Here, the electron spins associated with the paramagnetic Yb 3+ ions serve as the spies of their electronic and nuclear environments.…”