## 3 Results and Discussion
### Microstructural Analysis of the Sintered Specimens  
The microstructure of a sintered sample is shown in Figure 5. The structure of the specimen was found to be homogeneous with several small dark inclusions of distinguishable size. The three areas selected for the elemental analysis are illustrated in Figure 5b, and the numerical data are listed in Table 1.  
The data in Table 1 suggest that some non-uniformity of cera distribution in the zirconia matrix took place. However, its scale does not threaten the strength characteristics of the sintered material. From the perspective of fracture toughness, the proportion of tetragonal to monoclinic zirconia appeared more important. Overall, the \(t\)-ZrO\({}_{2}\) phase constituted ca. 95%, while the content \(m\)-ZrO\({}_{2}\) phase was ca. 5% in the sintered specimen. An increase in the monoclinic phase content upon cooling of zirconia sintered at temperatures higher than 1400 \({}^{\circ}\)C was reported in [41], which should not be expected in the present experiments with the zirconia sintered at 1400 \({}^{\circ}\)C. Thus, the negative effect of the monoclinic phase could be considered negligible.  
The presence of the different phases (i.e., monoclinic, tetrahedral, and cubic) is evidenced in the experimental studies. The histogram shown in Figure 6 provides a concise overview of these data. The horizontal axis shows the mol% value, while the \(Y\)-axis is utilized to demonstrate the number of mentions of these structures in the literature.  
When the mol% of CeO\({}_{2}\) in a given composite falls between 10% and 80%, the existence of the composite in various phases has been reported. The higher CeO\({}_{2}\) content, the higher the symmetry (for mol% \(<\) 8% formulation, it is typically monoclinic, 8 \(<\) mol% \(<\) 75% tetrahedral, or cubic and mol% \(>\) 75% cubic). The nanopowders with mol% equal to 10, 25, 50, and 75% exhibit tetrahedral symmetry, while with mol% equal to 90% exhibits cubic symmetry. Consequently, elevated mol% is associated with higher symmetry.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Spectrum No.** & **O, wt.\%** & **Ce, wt.\%** & **Zr, wt.\%** \\ \hline Spectrum 1 & 30.5 & 5.39 & 64.1 \\ Spectrum 2 & 30.8 & 4.99 & 64.2 \\ Spectrum 3 & 31.9 & 4.27 & 64.8 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Elemental analysis of sintered ZrO\({}_{2}\)–5 wt.% CeO\({}_{2}\) specimen.  
Figure 5: The sintered specimen ZrO\({}_{2}\) stabilized with 5 wt.% CeO\({}_{2}\): (**a**) Microstructure; (**b**) Spectra areas for elemental analysis.  
The addition of CeO\({}_{2}\) results in a significant enhancement of the stability, high-temperature resistance, and mechanical properties of ZrO\({}_{2}\). In contrast, the higher amounts of CeO\({}_{2}\) enhance the mobility of grain boundaries and increase the grain size following sintering. Therefore, the CeO\({}_{2}\) addition should be minimized. As demonstrated in Figure 6, at low molar percentage values (below 8 mol%), the m-phase has thus far been achieved. The electroconsolidation method outlined in this study facilitates the production of a t-phase composite comprising only 5 mol% of CeO\({}_{2}\), a distinctive feature.