“…Rocksalt EuO is the only rare earth monoxide known to be thermodynamically stable at ambient pressure (i.e., it will not decompose to Eu and Eu 2 O 3 , although it will oxidize in the presence of oxygen and, as all rare earth oxides, will react with water vapor, forming hydroxides). EuO has been synthesized by direct combustion of the metal, reaction of Eu with Eu 2 O 3 , and grown as single crystals with varying stoichiometry from Eu-Eu 2 O 3 melt [ 90 , 91 ]. Close to stoichiometric EuO is a semiconductor, but EuO 0.7 shows metallic conductivity.…”