The stabilizing of ZrO2 by rare earth oxides of atomic number 58 to 71. Pt. 2

Investigations were made on the stabilizing of ZrO2 by all rare earth oxides (58-71) under constant conditions. It was found that all rare earth oxides stabilize the ZrO2 forming a solid solution. The only exception is PrO2, which under certain working conditions does not fully stabilize ZrO2. Furthermore, the limits of the mol% shares for complete stabilization of ZrO2 were determined. It was also found that the partial stabilization of ZrO2 takes place at fairly low mol% shares. It was observed that the oxides with lower atomic numbers (58, 59, 60) behave differently to the remaining rare earths. The stabilizing limits of these oxides deviate from oxide to oxide to such an extent that they bear no relation to any physical-chemical constants of these elements. It was furthermore attempted to additionally comment on the ZrO2 stabilization conditions already given by Ruff and Ebert as well as Dietzel and Tober, i.e. that the stabilizing ionic radii must be larger than those of the Zr4+ ions. This rule may be taken as valid with only two exceptions. (orig.)