Nuclear Magnetic Resonance in Metal Tungsten Bronzes

Abstract

The nuclear magnetic resonances of Li⁷, Na²³, and Tl^203,205 have been studied in metal tungsten bronzes (M_xWO₃) in those composition ranges (x values) which possess metallic properties as evidenced by their electrical conductivity. In all cases, the shifts of these resonances with respect to diamagnetic reference compounds were found to be extremely small, indicating that the nuclei of the metal atoms do not interact with the conduction electrons as in the case of ordinary metals. This appears to result from the occurrence of either a radial or an angular node in the conduction band wave functions at the metal atom positions. In the case of the thallium tungsten bronze, linewidth results indicate the presence of indirect nuclear spin exchange interactions.