Nuclear magnetic resonance study of NbBe x compounds

Abstract

Nuclear magnetic resonance techniques have been employed to study powder samples of the compounds NbBe 2, NbBe 3, Nb 2Be 17 and NbBe 12. Nuclear quadrupole coupling constants and Knight shifts were determined for the Nb sites in these compounds. The 93 Nb NMR from NbBe 2 is a single unsplit line with zero quadrupole coupling constant and a Knight shift of 0.70 ± 0.03%. The 93Nb NMR from a NbBe 3 sample shows the presence of three resonance lines having values of e 2qQ h = 0, 24.2 ± 0.2, 30.1 ± 0.3 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 NbBe 2 impurity. The 93Nb NMR of Nb 2Be 17 exhibits a quadrupole coupling, e 2qQ h = 5.93 ± 0.15 MHz , and a Knight shift, K axiat = 0.014% and K isotropic = 0.34 ± 0.02%. The 93Nb resonance from NbBe 12 was split by a quadrupole interaction of e 2qQ h = 21.7 ± 0.3 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.