A Review of 91Zr Solid-State Nuclear Magnetic Resonance Spectroscopy

Solid-state NMR (SSNMR) is a powerful probe of the molecular-level geometric, electronic, and magnetic environment about a target nucleus. Significant advances have been made in Zr-91 SSNMR spectroscopy since its inception, particularly within the past 25 years. Zr-91 is an unfavorable nucleus for SSNMR studies, owing to its small gyromagnetic ratio, low natural abundance, and moderate quadrupole moment. In the past, studies were limited to Zr nuclei residing in high-symmetry local environments, such as metals and Laves-phase materials. The availability of high magnetic fields and advanced pulse sequences, in addition to significant progress in complementary theoretical characterization techniques such as ab initio quantum chemical calculations, has rendered a plethora of Zr environments amenable to Zr-91 SSNMR experiments. In this review, we first discuss the background and applications of zirconium, followed by a brief introduction of relevant SSNMR parameters. Zr-91 SSNMR experimental techniques employed over the years, along with their benefits and drawbacks, are then discussed in detail. Historical accounts of zero-field and field-swept Zr-91 SSNMR experiments from 1964 to 1990 are reviewed, followed by modern pulsed-Fourier transform Zr-91 experiments from 1990 to 2000, and recent advances from 2000 to 2014. The wealth of information available from modern Zr-91 SSNMR experiments holds great promise for future applications to a variety of Zr systems.