Valence electron structure and properties of stabilized ZrO2

To reveal the properties of stabilizers in ZrO₂ on nanoscopic levels, the valence electron structures of four stable ZrO₂ phases and c-ZrO₂ were analyzed on the basis of the empirical electron theory of solids and molecules. The results showed that the hybridization levels of Zr atoms in c-ZrO₂ doped with Ca and Mg dropped from B17 to B13, the hybridization levels of Zr atoms in c-ZrO₂ doped with Y and Ce dropped from B17 to B15, and that the four stabilizing atoms all made the hybridization levels of O atoms drop from level 4 to level 2. The numbers of covalent electrons in the strongest covalent bond in the descending order are c-ZrO₂>Zr_0.82Ce_0.18O₂>Zr_0.82Y_0.18O_1.91>Zr_0.82Mg_0.18O_1.82>Zr_0.82Ca_0.18O_1.82. The bond energies of the strongest covalent bond and the melting points of the solid solutions in the descending order are Zr_0.82Ce_0.18O₂> c-ZrO₂>Zr_0.82Y_0.18O_1.91>Zr_0.82Mg_0.18O_1.82>Zr_0.82Ca_0.18O_1.82. The percentages of the total number of covalent electrons in the descending order are c-ZrO₂>Zr_0.82Y_0.18O_1.91> Zr_0.82Ce_0.18O₂>Zr_0.82Mg_0.18O_1.82> Zr_0.82Ca_0.18O_1.82. From the above analysis, it can be concluded that the stabilizing degrees of the four stabilizers in the descending order are CaO> MgO>Y₂O₃>CeO₂. Supported by the Major Project of the National Natural Science Foundation of China (Grant No. 90505015)