Low-temperature and high-temperature experiments on electron-irradiated Li2O: Molecular-oxygen freezing and metallic-lithium melting

Magnetization measurements of Li2O crystals between 1.4 and 300 K reveal a diamagnetic-to-paramagnetic transformation of the samples, containing Li-co lloids after electron irradiation near room temperature, and exhibit a brea k near 50 K as well as an antiferromagnetic ordering transition at 38 K. Th e magnetism is attributed to less than or equal to 1% of molecular oxygen g as, freezing at 50 K, which is contained in micron-size cavities and produc ed simultaneously with the Li colloids. The earlier Li-7 NMR experiments we re extended to higher temperatures, in the range 300-520 K. The Knight-shif ted Li-metal signal at similar to 260 ppm is weakening during heating, due to annealing, but maintains its split double structure. The separation betw een the two peak components diminishes by similar to 10%, after crossing th e Li melting point at 453 K. The interpretation of these observations is di scussed. (C) 2000 Elsevier Science B.V. All rights reserved.