Structural Characterization of Rare-Earth Doped Yttrium Aluminoborate Laser Glasses Using Solid State NMR

Abstract

The structure of laser glasses in the system (B 2 O 3 ) 0.6 {(Al 2 O 3 ) 0.4-x (Y 2 O 3 ) x } (0.1 e x e 0.25) has been investigated by means of 11 B, 27 Al, and 89 Y solid state NMR as well as Y-3d core-level X-ray photoelectron spectroscopy. 11B magic-angle spinning (MAS) NMR spectra reveal that the majority of the boron atoms are three-coordinated, and a slight increase of four-coordinated boron content with increasing x can be noticed. 27 Al MAS NMR spectra show that the alumina species are present in the coordination states four, five and six. All of them 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, nonsegregated glass structure. For the first time, 89 Y solid state NMR has been used to probe the local environment of Y 3+ ions in a glass-forming system. The intrinsic sensitivity problem associated with 89 Y NMR has been overcome by combining the benefits of paramagnetic doping with those of signal accumulation via Carr-Purcell spin echo trains. Both the 89 Y chemical shifts and the Y-3d core level binding energies are found to be rather sensitive to the yttrium bonding state and reveal that the bonding properties of the yttrium atoms in these glasses are similar to those found in the model compounds YBO 3 and YAl 3 (BO 3 ) 4 . Based on charge balance considerations as well as 11 B NMR line shape analyses, the dominant borate species are concluded to be meta-and pyroborate anions.

Characterization of the glass-to-vitroceramic transition in yttrium aluminum borate laser glasses using solid state NMR

“…In the glassy state, the dominant fraction of boron is three-coordinated, giving rise to a broad structured lineshape characterized by second-order quadrupolar perturbations. As previously discussed, the lineshape suggests a non-axially symmetric electric field gradient, consistent with the formation of mostly metaborate (three-coordinate boron with one non-bridging oxygen) and pyroborate (three-coordinate boron with two non-bridging oxygen) groups [20]. The chemical shift difference between the latter two units appears to be obscured by a wide distribution of quadrupolar coupling parameters and chemical shifts.…”

“…40), containing Yb at variable dopant levels were prepared as described previously [6,20], by the conventional melt-quenching technique, using a resistive furnace open to the atmosphere. To obtain a water free starting material, glassy boron oxide was prepared by annealing commercial B 2 O 3 (ALDRICH, 99%) at 450 1C for 2 h, with a heating rate of 5 1C/min, for the evaporation of water.…”

“…In contrast to diffraction techniques, solid state NMR methods are equally sensitive to the glassy and crystalline constituents, resulting in quantitatively representative spectra. Benefitting from the potential of advanced double resonance solid state NMR strategies to provide useful structural information on a local level [18,19], we have recently developed a detailed description of the framework structure of yttrium aluminoborate glasses [20]. While 11 B and 27 Al magic-angle spinning (MAS) NMR experiments are informative regarding the coordination states of the boron and aluminum atoms, complementary 11 B/ 27 Al double resonance NMR studies have given quantitative information regarding the boronaluminum connectivities in the network.…”

YPdSn and YPd2Sn: Structure, 89Y solid state NMR and 119Sn Mössbauer spectroscopy

“…While continuing our systematic exploration of 45 Sc NMR interaction parameters in relation to the local environments and electronic structures of ternary Sc x T y X z (T¼ transition metal; X¼element of the 3rd, 4th, and 5th main group) intermetallic compounds [6] we are now also pursuing parallel 89 Y investigations on structurally related yttrium compounds. While highresolution solid state 89 Y NMR spectroscopy of diamagnetic insulators has been well-developed by now [7][8][9][10][11][12][13][14], NMR applications to metallic systems have thus far been limited mostly to low-resolution work on the electronic and magnetic properties of yttrium hydrides [15][16][17][18][19], yttrium-iron based alloys [20][21][22] and borocarbides [23]. The only structurally focused high-resolution Mössbauer spectroscopy.…”

Thermo-optical characteristics and concentration quenching effects in Nd3+doped yttrium calcium borate glasses

“…Recently, we have reported on the luminescence and thermo-optical properties of Nd 3+ -doped YAl 3 (BO 3 ) 4 (YAlB) glasses with higher fluorescence quantum efficiency than the Nd:YAB crystal, 9 and on a detailed structural investigation of the glasses, and their corresponding vitroceramics, as a function of compositional changes. 11,12 However, to the best of our knowledge, there have been no reports on the spectroscopic and thermo-optical characterization of undoped and Nd 3+ -doped YCa 4 O(BO 3 ) 3 (YCaB) glasses, which have been recently introduced by some of us. 10,19 A structural study of samples with compositions xY 2 O 3-8xCaO-(100−9x)B 2 O 3 (x = 4, 5, and 6 mol%), via Raman and infrared reflectance spectroscopies, has shown that the glasses contain a complex distribution of three-coordinated ortho and pyroborate groups and four-coordinated pentaborate groups, and as the CaO a) Electronic mail: andreasc@ifsc.usp.br.…”