Nuclear magnetic resonance study of the transition metal monoborides. II. Nuclear electric quadrupole and magnetic shift parameters of the metal nuclei in VB, CoB, and NbB

Abstract

Measurements are reported of the nuclear electric quadrupole interaction parameters (coupling constant and asymmetry) and the several anisotropic Knight shift parameters of the ⁵¹V, ⁵⁹Co, and ⁹³Nb nuclear magnetic resonance spectra in VB, CoB, and NbB monoborides, respectively. A detailed account is given of the method of extracting these parameters from the experimental spectra. The quadrupole coupling constants and asymmetry parameters are ⁵¹VB, 1.75 MHz, 0.95; ⁵⁹CoB, 25.2 MHz, 0.74; and ⁹³NbB, 20.4 MHz, 0.065. The isotropic components of the Knight shifts are all positive: ⁵¹VB, 0.32%; ⁵⁹CoB, 0.69%; and ⁹³NbB, 0.24%. Despite the close similarity in the structures of these compounds, neither the quadrupole nor Knight shift parameters scale in a simple manner with the nuclear properties. Thus, even in the cases of VB and NbB, it appears that a rigid‐band type approximation furnishes a poor description of the actual changes in the electronic structure.