Crystal Structure Studies by Single-Crystal NMR Spectroscopy. ⁷¹Ga and ⁶⁹Ga Single-Crystal NMR of β-Ga₂O₃ Twins

Abstract

71 Ga and 69 Ga single-crystal NMR spectra of a -Ga 2 O 3 twin have been analyzed in terms of the 71 Ga/ 69 Ga quadrupole coupling and chemical shielding anisotropy (CSA) interactions. Analyses of the magnitudes and orientations of the interaction tensors for the two distinct crystallographic gallium sites in the two twin crystals resulted in accurate values for the parameters describing the quadrupole coupling and CSA tensors. Moreover, it has been possible to determine the actual twin-law of our sample crystal. Along with a recent 71 Ga single-crystal NMR investigation of YGG, this work shows that gallium CSA generally has to be taken into account in addition to the dominant quadrupole coupling interaction.S0002-7863(98)01666-7 CCC: $15.00

Solid-state NMR calculations for metal oxides and gallates: Shielding and quadrupolar parameters for perovskites and related phases

“…Experimental values Q = -0.02558 and 0.106 barns have been used for the 17 O and 71 Ga electric quadrupole moments, respectively [27,33]. For reference, the C Q -values presented for 71 Ga sites may be converted to those appropriate for 69 Ga by multiplying by a factor Q( 69 Ga)/Q( 71 Ga) = 1.598. The full and diagonalised shielding and electric field gradient tensors computed for each site in all of the materials studied are presented in the Supplementary Information.…”

“…Moreover, there remain important questions as to the improvements obtainable from treatments of electron exchange and correlation beyond the pure DFT functional applied here, though it is noted that the deployment of such methods within the GIPAW approach is not yet routine. Table 4 Comparison of the experimental and computed properties related to the anisotropy of, asymmetry in and relative orientation of the chemical shift and electric field gradient tensors at 71 Ga sites [48,[59][60][61][62][63][64][65][66][67][68][69]. …”

An overview of selected current approaches to the characterization of aqueous inorganic clusters

“…With these advancements, ssNMR offers a unique modality for the characterization of molecular clusters for multiple reasons. 59,61,62 Gallium has two NMR active isotopes, 69 Ga and 71 Ga, which are quadrupolar, and both have spin I = 3/2. ssNMR is both element-selective and a quantitative spectroscopic technique where the NMR resonances can be recorded such that the signal is proportional to the number and type of sites present for the isotope being probed in the material.…”

High-resolution two-dimensional NMR spectra of half-integer-spin quadrupolar nuclei from one-dimensional projections

“…--- Figure 4 here ---While the MQMAS and STMAS techniques fail for nuclei with large quadrupole couplings due to low sensitivity in the case of MQMAS [32] and excessive line-broadening for STMAS [33], there is no such limitation to CQ-PRODI. To investigate this appealing property of CQ-PRODI we have applied this technique to 71 Ga spectra of β-Ga 2 O 3 which contains a Ga VI and a Ga IV site with quadrupole couplings of 8.3 MHz and 11.2 MHz, respectively [12,34]. These values are well beyond the size of the quadrupole couplings amenable to MQMAS or STMAS, and only DAS [27] and single-crystal NMR [34] have achieved complete resolution of the two sites.…”