Characterization of Li-colloids in electron-irradiated Li2O-crystals by neutron scattering

Abstract : Lithium oxide crystals containing metallic Li-colloids created by MeV-electron irradiation around room temperature were analyzed by elastic neutron scattering. High-resolution scans on a triple-axis spectrometer show that the main Bragg peaks of the irradiated Li2O crystals are broadened and exhibit diffuse shoulders due to the introduced lattice damage. Extensive search in reciprocal space reveals the presence of weak, yet well-defined, point-like intensities which can be identified as Bragg reflections of bulk bcc lithium. The Li precipitates are aligned according to the orientational relation [1 1 0]Li//[1 1 1]Li2O and may correspond to the large (>1 µm) Li-colloids observed earlier by conduction electron spin resonance (CESR) and by optical microscopy. Small-angle neutron scattering on the same crystals indicates an anisotropic distribution of non-spherical precipitates whose diameters lie in the range of several hundred angstroms and which possibly represent the small Li-colloids ("1 µm) characterized by CESR.