STABILIZATION OF CUBIC ZIRCONIA WITH MANGANESE OXIDE

A directionally solidified eutectic (DSE) of MnO-ZrO2 has been investi gated using a variety of electron optical techniques. It is found that considerable MnO goes into ZrO2 to form a substitutional solid soluti on. About 14 wt% of MnO is soluble in ZrO2 close to the eutectic tempe rature. The solubility of ZrO2 in MnO, however, is quite low, less tha n 0.50 wt%. Electron diffraction experiments indicate that ZrO2 (MnO) has the cubic fluorite structure. Diffuse scattering, similar to other cubic zirconias (e.g., CaO, MgO stabilized zirconia), is also observe d in manganese-stabilized zirconia. Diffuse scattering indicates the p resence of oxygen vacancies and thus confirms the defect nature of the fluorite structure. Electron energy loss spectrometry (EELS) fine str ucture analysis of the Mn L23 edge provided clear evidence that Mn is present as Mn2+ in Mn-stabilized cubic ZrO2.