Examination of the orientation dependence of the quasielastic scattering of neutrons by pellicular zirconium phosphate film

Abstract

Variable-temperature quasielastic neutron scattering (QNS) measurements on a time-of-flight spectrometer have been used in investigation of the orientation dependence of quasielastic scattering by a film of pellicular zirconium phosphate [p-ZrP, Zr(HPO₄)₂·1.3H₂O]. The partially oriented film, in the plane of which the lamellae of the ZrP structure lie, was produced by intercalation and deintercalation reactions of n-propylamine with microcrystalline α-zirconium phosphate. QNS spectra were recorded with the plane of the film inclined at 135°(‘transmission’) and 45°(‘reflection’) to the incident neutron beam. Quasielastic broadenings consistent with hydrogenic species undergoing motions with a timescale ≈10^–12 s in p-ZrP were observed at T>318 K, and the scattering law was also found to be dependent on sample orientation. The dependence on scattering vector magnitude, Q_el, of the scattering law with the sample in ‘transmission’ geometry [in which scattering was dominated by motion in the plane of the film (parallel to ZrP lamellae)] indicated detection of both reorientational and translational (diffusion in the plane of the film) motions. Quasielastic scattering with the sample in ‘reflection’ geometry was less intense and could not be modelled with a simple scattering law.