A procedure was developed for the determination of the locations of shoulders and singularities of polycrystalline nuclear magnetic resonance (NMR) powder patterns in the presence of both nuclear quadrupole and anisotropic magnetic shift interactions. This determination was performed for both the satellites and the central transition of the NMR spectra of nuclei with half‐integral spin I. Typical theoretical behavior of the powder pattern for the central transition in the presence of both quadrupolar and magnetic shift interactions is shown in a series of examples. In addition, a computer program was devised which calculated the powder pattern for arbitrary quadrupolar and magnetic shift parameters, convoluted it with a function that simulates the effects of dipolar broadening, and took the derivative of the result. The quadrupolar and magnetic shift parameters in three metavanadate compounds (NH4VO3, KVO3, and NaVO3) are determined using these methods.

Nuclear Magnetic Resonance Powder Patterns in the Presence of Completely Asymmetric Quadrupole and Chemical Shift Effects: Application to Metavanadates

51V Solid state NMR studies of vanadia based catalysts

51V MAS NMR spectroscopy: determination of quadrupole and anisotropic shielding tensors, including the relative orientation of their principal-axis systems

The 51V NMR of the diamagnetic V5+ and paramagnetic V4+ ions has been studied in the semiconducting V2O5–P2O5 glass system From computer‐simulation studies of the 51V NMR experimental spectra due to the V5+ sites, it has been determined that the spectra obtained at the higher spectrometer frequencies can be described by a skewed distribution of powder patterns arising from axially symmetric chemical shifts The most probable value of the chemical shift distribution (Σ‖)mp of the chemical shift parameter Σ‖ decreases with increasing V2O5 content and (Σ⊥)mp is independent of glass composition An estimate of the nuclear quadrupole coupling constant of the V5+ site has been made; it ranges from 10 to 15 MHz as the V2O5 content of the glass is increased The NMR data are interpreted in terms of two types of VO5 units in the glass One is a VO5 unit similar to that in crystalline V2O5 and the other is a VO5 unit with a PO4 unit substituted for the apex oxygen From ESR intensity measurements, the ratio of t

Magnetic Resonance Study of the V2O5–P2O5 Semiconducting Glass System

Magnetic Shielding and Susceptibility Anisotropies

The quadrupole‐coupling and the chemical‐shift tensors of 51V were measured in a single crystal of V2O5 at room temperature. The quadrupole‐coupling constant is 805(6) kc/sec and the anisotropy factor η is 0.04(1). The chemical‐shift tensor, relative to a solution of Na3VO4, has principal values of −1.8(4)×10−4, +6.5(3)×10−4, and −3.0(3)×10−4. Attempts to calculate the electric‐field‐gradient tensor at the vanadium nucleus, using a point‐charge model, led to results that did not agree with experiment.

C. V. Stager

Papers

Nuclear Magnetic Resonance Study of V2O5