Muon motion in titanium hydride
Citations Over TimeTop 21% of 1989 papers
Abstract
Motional narrowing of the transverse-field muon-spin rotation signal has been reported previously for \ensuremath{\gamma}-${\mathrm{TiH}}_{\mathrm{x}}$ with x=1.83, 1.97, and 1.99. An analysis of the results for ${\mathrm{TiH}}_{1.99}$ near room temperature indicates that the mechanism responsible for the motion of the muon out of the octahedral site is thermally activated diffusion with an attempt frequency comparable to the optical vibrations of the lattice. The motional narrowing in ${\mathrm{TiH}}_{1.97}$ near 500 K is interpreted with the aid of Monte Carlo calculations which simulated the effect of muon and proton motion upon the field-correlation time for the muon. The results of these simulations coupled with published proton nuclear-magnetic-resonance ${T}_{1}$ measurements indicate that the field-correlation time for the muon can be explained if the rate of motion for the nearest-neighbor protons is decreased relative to the hopping rate for the unperturbed lattice.