High-resolution low-field nuclear magnetic resonance (NMR) spectroscopy has found wide application for characterization of liquid compounds because of the low maintenance cost of modern permanent magnets. Solid-state NMR so far is limited to low-resolution measurements of static powders, because of the limited space available in this type of magnet. Magic-angle sample spinning and low-magnetic fields are an attractive combination to achieve high spectral resolution especially for paramagnetic solids. Here we show that magic angle spinning modules can be miniaturized using 3D printing techniques so that high-resolution solid-state NMR in permanent magnets becomes possible. The suggested conical rotor design was developed using finite element calculations and provides sample spinning frequencies higher than 20 kHz. The setup was tested on various diamagnetic and paramagnetic compounds including paramagnetic battery materials. The only comparable experiments in low-cost magnets known so far, had been done in the early times of magic angle spinning using electromagnets at much lower sample spinning frequency. Our results demonstrate that high-resolution low-field magic-angle-spinning NMR does not require expensive superconducting magnets and that high-resolution solid-state NMR spectra of paramagnetic compounds are feasible. Generally, this could introduce low-field solid-state NMR for abundant nuclei standard as a routine analytical tool.

由于现代永磁体的维护成本较低，高分辨率低场核磁共振 (NMR) 光谱已广泛应用于液体化合物的表征。迄今为止，固态核磁共振仅限于静态粉末的低分辨率测量，因为此类磁体的可用空间有限。魔角样品旋转和低磁场是实现高光谱分辨率的有吸引力的组合，特别是对于顺磁性固体。在这里，我们展示了可以使用 3D 打印技术将魔角旋转模块小型化，从而使永磁体中的高分辨率固态 NMR 成为可能。建议的锥形转子设计是使用有限元计算开发的，并提供高于 20 kHz 的样本旋转频率。该装置在各种抗磁性和顺磁性化合物（包括顺磁性电池材料）上进行了测试。迄今为止，已知的唯一可比较的低成本磁体实验是在魔角旋转的早期使用电磁体以低得多的样品旋转频率进行的。我们的结果表明，高分辨率低场魔角旋转核磁共振不需要昂贵的超导磁体，并且顺磁性化合物的高分辨率固态核磁共振谱是可行的。一般来说，这可以引入低场固态核磁共振作为常规分析工具来获取丰富的核标准。