“…This simplifies recording such spectra and also contributes to improved sensitivity. For example earlier studies in three crystalline ZrO 2 phases, monoclinic, tetragonal, and orthorhombic, required recording 91 Zr NMR spin-echo spectra in a frequency-stepped manner [29,90,92]. Later work employed 91 Zr NMR frequency-stepped QCPMG technique to record such spectra at 9.4 T with much better quality and in shorter time [24,87].…”