Metals, alloys and compounds - high purities do make a difference!

The influence of impurity atoms, especially interstitial elements, on some of the properties of the pure rare earth metals and the stabilization of non-equilibrium structures of the metals (i.e. non-existent polymorphs) is discussed. The effect of impurities on rare earth intermetallic and non-metallic compounds is examined: this includes the composition and structure of line compounds; the nominal vs. true composition of solid solution intermediate phases; and the stabilization of non-existent binary phases (i.e. ternary compounds).