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

Recent progress in solid-state NMR of spin-½ low-γ nuclei applied to inorganic materials

Significant technological and methodological advances in solid-state NMR techniques in recent years have increased the accessibility of nuclei with small magnetic moments (hereafter termed low-γ) underpinning an increased range of applications of such nuclei. These methodological advances are briefly summarised, including improvements in hardware and pulse sequences, as well as important developments in associated computational methods (e.g. first principles calculations, spectral simulation). Here spin-½ nuclei are the focus, with this Perspective complementing a very recent review that looked at half-integer spin low-γ quadrupolar nuclei. Reference is made to some of the original reports of such spin-½ nuclei, but recent progress in the relevant methodology and applications to inorganic materials (most within the last 10 years) of these nuclei are the focus. An overview of the current state-of-the-art of studying these nuclei is thereby provided for both NMR spectroscopists and materials researchers.

Nanoscopic yttrium oxide fluorides: non-aqueous fluorolytic sol-gel synthesis and structural insights by 19F and 89Y MAS NMR

Nanoscopic yttrium acetate fluorides Y(CH(3)COO)(3-z)F(z) and yttrium oxide fluorides YO(3-z)/(2)F(z )were prepared with tunable Y/F molar ratios via the fluorolytic sol-gel route. All samples were characterized by X-ray diffraction, elemental analysis and thermal analysis. In addition, local structures of all samples were studied by (19)F MAS, (19)F-(89)Y CP MAS and (1)H-(89)Y CP MAS NMR spectroscopy and the respective chemical shifts are given. For both classes of compounds, only the fluorination using one equivalent of F (z = 1) leads to defined, well crystalline matrices: yttrium acetate fluoride Y(CH(3)COO)(2)F and r-YOF.

C-REDOR curves of extended spin systems

The convergence of simulated C-REDOR curves of (infinitely) large spin systems is investigated with respect to the number of spins considered in the calculations. Taking a sufficiently large number of spins (>20,000 spins) into account enables the simulation of converged C-REDOR curves over the entire time period and not only the initial regime. The calculations are based on an existing approximation within first order average Hamiltonian theory (AHT), which assumes the absence of homonuclear dipole-dipole interactions. The C-REDOR experiment generates an average Hamiltonian close to the idealized AHT behavior even for multiple spin systems including multiple homonuclear dipole-dipole interactions which is shown from numerically exact calculations of the spin dynamics. Experimentally it is shown that calculations accurately predict the full, experimental C-REDOR curves of the multi-spin systems (31)P-(19)F in apatite, (31)P-(1)H in potassium trimetaphosphimate and (1)H-(31)P in potassium dihydrogen phosphate. We also present (13)C-(1)H and (15)N-(1)H data for the organic compounds glycine, l-alanine and l-histidine hydrochloride monohydrate which require consideration of molecular motion. Furthermore, we investigated the current limits of the method from systematic errors and we suggest a simple way to calculate errors for homogeneous and heterogeneous samples from experimental data.