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.

11B and 89Y solid state MAS NMR spectroscopic investigations of the layered borides YTB4 (T = Mo, W, Re)

The YCrB4 type borides YTB4 (T = Mo, W, Re) were synthesized from the elements by arc-melting and subsequent annealing. The structures were refined from single crystal X-ray diffractometer data: Pbam, a = 602.84(8), b = 1164.5(1), c = 361.20(4) pm, wR2 = 0.0404, 624 F2 values, 26 variables for YMoB4, a = 603.00(7), b = 1165.1(1), c = 360.63(6) pm, wR2 = 0.0487, 474 F2 values, 26 variables for YWB4, and a = 596.67(6), b = 1154.4(1), c = 360.21(4) pm, wR2 = 0.0465, 544 F2 values, 26 variables for YReB4. The boron atoms build up planar networks which are a tessellation of slightly distorted pentagons and heptagons. Adjacent networks coordinate the transition metal and yttrium atoms in the form of pentagonal and heptagonal prisms, respectively. The four crystallographically distinct boron sites are differentiated by high-resolution 11B solid state isotropic magnetic shifts and nuclear electric quadrupolar coupling constants. Partial site assignments are possible based on comparisons with electric field gradient calculations using the WIEN2k code. 89Y MAS NMR spectroscopic studies suggest substantially weaker Knight shift contributions to the resonance frequencies when compared to other intermetallic yttrium compounds, including other ternary yttrium boride compounds measured previously.

29Si,47Ti,49Ti and195Pt solid state MAS NMR spectroscopic investigations of ternary silicides TPtSi, germanides TPtGe (T = Ti, Zr, Hf) and stannide TiPtSn

Silicides TPtSi, germanides TPtGe (T = Ti, Zr, Hf) and stannide TiPtSn show well resolved²⁹Si,⁴⁷Ti,⁴⁹Ti and¹⁹⁵Pt solid state MAS NMR spectra.

Equiatomic intermetallic compounds YTX (T = Ni, Ir; X = Si, Ge, Sn, Pb): a systematic study by 89Y solid state NMR and 119Sn Mössbauer spectroscopy

The equiatomic TiNiSi type tetrelides YTX (space group Pnma) with T = Ni, Ir and X = Si, Ge, Sn, Pb were synthesized from the elements by arc-melting or via high-frequency-melting of the elements in sealed niobium ampoules.