Lithium colloids and color center creation in electron-irradiated Li2 NH observed by electron-spin resonance

We have irradiated Li2 NH powder with MeV electrons at room temperature and investigated the introduced defects with electron spin resonance. Conduction electron spin resonance indicates the presence of nanosize metallic Li colloids seen as a Lorentzian line with a g=2.0023 and a linewidth ΔH=50 μT. A second, broader signal (ΔH=3-4 mT) appears superimposed upon the Li line at low T (Curie-type behavior) which exhibits complex T dependence with a break near 180 K for its g value and ΔH. We are suggesting for the latter a vacancy-type defect in the NH sublattice, with freezing of its H component below 180 K. When heated both the Li colloids and the color centers anneal around 100 °C probably due to hydrogen evolution and subsequent chemical degradation.