Dynamic nuclear polarization NMR of low-γ nuclei: Structural insights into hydrated yttrium-doped BaZrO₃

We demonstrate that solid-state NMR spectra of challenging nuclei with a low gyromagnetic ratio such as yttrium-89 can be acquired quickly with indirect dynamic nuclear polarization (DNP) methods. Proton to ⁸⁹Y cross polarization (CP) magic angle spinning (MAS) spectra of Y³⁺ in a frozen aqueous solution were acquired in minutes using the AMUPol biradical as a polarizing agent. Subsequently, the detection of the ⁸⁹Y and ¹H NMR signals from technologically important hydrated yttrium-doped zirconate ceramics, in combination with DFT calculations, allows the local yttrium and proton environments present in these protonic conductors to be detected and assigned to different hydrogen-bonded environments.