Nuclear magnetic resonance study of NbBex compounds

Nuclear magnetic resonance techniques have been employed to study powder samples of the compounds NbBe₂, NbBe₃, Nb₂Be₁₇ and NbBe₁₂. Nuclear quadrupole coupling constants and Knight shifts were determined for the Nb sites in these compounds. The ${}^{93}\text{Nb NMR}$ from NbBe₂ is a single unsplit line with zero quadrupole coupling constant and a Knight shift of 0.70 ± 0.03%. The ⁹³Nb NMR from a NbBe₃ sample shows the presence of three resonance lines having values of $\text{e}{}^2\text{qQ}\text{h}\text{= 0, 24.2 ± 0.2, 30.1 ± 0.3}\text{MHz}$ and corresponding Knight shifts of 0.69 ± 0.03, 0.72 ± 0.03, 0.53 ± 0.03%. One of these lines was identified as a NbBe₂ impurity. The ${}^{93}\text{Nb NMR}$ of Nb₂Be₁₇ exhibits a quadrupole coupling, $\text{e}{}^2\text{qQ}\text{h}\text{= 5.93 ± 0.15}\text{MHz}$, and a Knight shift, K_axiat = 0.014% and K_isotropic = 0.34 ± 0.02%. The ${}^{93}\text{Nb}$ resonance from NbBe₁₂ was split by a quadrupole interaction of $\text{e}{}^2\text{qQ}\text{h}\text{= 21.7 ± 0.3}\text{MHz}$ and a Knight shift of 0.55% ± 0.02%. The beryllium NMR was examined, yielding little information, since no measurable quadrupole interaction or Knight shift were present.