PROTONIC LOCATION IN HYDROGEN MOLYBDENUM BRONZES HXMOO3 AS STUDIED BY PROTON NMR LINESHAPE ANALYSIS

Rigid lattice proton NMR spectra are observed in four types of hydrogen molybdenum bronzes HxMoO3 with pulsed NMR. Lineshapes of the spectra are analyzed by computer-simulation. We conclude that the spectrum of type I (0.21 ≦ x ≦ 0.40) is a superposition of the spectrum originating in a two-spin system (Pake-doublet) and the one originating in a three-spin system. On the other hand, the spectra of types II (0.85 ≦ x ≦ 1.04), III (1.55 ≦ x ≦ 1.72), and IV (x {reversed tilde equals} 2.0) consist of a Pake-doublet, a Gaussian, and a Lorentzian. The Gaussian and the Lorentzian are attributed to isolated and immobile protons, and mobile protons, respectively. From the analyses, portions of hydrogen contents of different locations and distances between nearest neighbor protons are determined for all four types of the bronzes. Transition of the protonic structure from type I to II is discussed. © 1992 Academic Press, Inc.