Evidence of molecular-oxygen inclusions in electron-irradiated Li2O crystals through magnetization measurements

We have measured the temperature-dependent magnetization of electron-irradiated Li2O crystals exhibiting metallic lithium colloids as determined by conduction-electron spin resonance. While diamagnetic before irradiation, the sample is paramagnetic afterwards, with an antiferromagnetic ordering transition at 38 K. The magnetism is attributed to less than or equal to 1 mol% of molecular oxygen produced together with the Li colloids. It is supposed to be contained in relatively incompressible cavities and to form a solid under "negative" pressure when freezing.