Beschreibung:
<jats:title>Abstract</jats:title><jats:p>In the present work, our aim is to decipher the cationic ordering in the octahedral and tetrahedral sheets of two Al‐rich synthetic materials, namely, phlogopites of nominal composition K(Mg<jats:sub>3‐x</jats:sub>Al<jats:sub>x</jats:sub>)[Al<jats:sub>1+x</jats:sub>Si<jats:sub>3‐x</jats:sub>O<jats:sub>10</jats:sub>](OH)<jats:sub>y</jats:sub>F<jats:sub>2‐y</jats:sub> and lepidolites in the system trilithionite–polylithionite with composition K (Li<jats:sub>x</jats:sub>Al<jats:sub>3‐x</jats:sub>)[Al<jats:sub>4‐2x</jats:sub>Si<jats:sub>2x</jats:sub>O<jats:sub>10</jats:sub>](OH)<jats:sub>y</jats:sub>F<jats:sub>2‐y</jats:sub>, by directly probing the aluminium distribution through <jats:sup>27</jats:sup>Al and <jats:sup>17</jats:sup>O magic‐angle spinning, multiple‐quantum magic‐angle spinning, and <jats:sup>27</jats:sup>Al‐<jats:sup>27</jats:sup>Al double‐quantum single‐quantum nuclear magnetic resonance (NMR) experiments. Notably, <jats:sup>27</jats:sup>Al‐<jats:sup>27</jats:sup>Al double‐quantum single‐quantum magic‐angle spinning NMR spectra, recorded at 9.34 and/or 20.00 T, show the spatial proximity or avoidance of the Al species inside or between the sheets. In both studied minerals, the ensemble of NMR data suggests a preference for <jats:sup>[4]</jats:sup>Al in the tetrahedral sheet to occupy position close to the <jats:sup>[6]</jats:sup>Al of the octahedral sheets.</jats:p>