On the nuclear magnetic resonance in metals and alloys

Abstract The shift of the nuclear resonance and the line width has been measured in α- and β-tin, thallium, lead and several alloys. While gray tin has no shift relative to the resonance in insulating compounds, white tin has an anisotropic shift of 0.79 per cent along the tetragonal axis and 0.74 per cent perpendicular to it. A theory for the anisotropy and asymmetry of the observed line is given. Thallium has an anomalously broad resonance line with a shift of 1.54 per cent. In thallium alloys the shift varies continuously with composition in each phase and has discontinuities when phase transitions occur. A maximum shift of 2.1 per cent has been found in a TlMg-alloy, while the NaTl structure exhibits a negative shift of −1.0 per cent. Quadrupolar effects are important when the nuclear spin I > 1 2 . The intensity of the copper resonance in pure copper can be increased by annealing and decreased by cold work. In alloys like α-brass and copper-silver the intensity decreases rapidly with increasing zinc or silver content. At 25 per cent zinc the copper resonance becomes unobservable. These effects are explained in terms of quadrupole interaction and can give information about the state of order or disorder on an atomic scale in the alloy.