## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c} \hline  & & **9-CSZ** & **2 MnCSZ** & **3 MnCSZ** & **4 MnCSZ** \\ \hline \multirow{6}{*}{m-ZrO\({}_{2}\)} & volume \% & 27.1 & 7.8 & 17.2 & 9.3 \\ \cline{2-5}  & a (Å) & 5.145 & 5.212 & 5.171 & 6.084 \\ \cline{2-5}  & b (Å) & 5.194 & 4.928 & 5.903 & 4.989 \\ \cline{2-5}  & c (Å) & 5.309 & 5.55 & 5.26 & 5.324 \\ \cline{2-5}  & \(\alpha=\gamma\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) \\ \cline{2-5}  & \(\beta\) & 99.174 & 99.693 & 99.137 & 100.791 \\ \cline{2-5}  & lattice volume (Å\({}^{3}\)) & 140.058358 & 140.5152436 & 158.5211616 & 158.7421548 \\ \cline{2-5}  & chemical composition & ZrO1.995 \(\pm\) 0.008 & ZrO1.992 \(\pm\) 0.003 & ZrO1.993 \(\pm\) 0.011 & ZrO1.988 \(\pm\) 0.020 \\ \hline \multirow{6}{*}{t-ZrO\({}_{2}\)} & volume \% & 65.9 & 53.6 & 21.8 & 17 \\ \cline{2-5}  & a = b (Å) & 3.626 & 3.619 & 3.633 & 3.657 \\ \cline{2-5}  & c (Å) & 5.11 & 5.129 & 5.129 & 5.101 \\ \cline{2-5}  & \(\alpha=\beta=\gamma\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) \\ \cline{2-5}  & lattice volume (Å\({}^{3}\)) & 67.18564636 & 67.17533877 & 67.69607588 & 68.21898355 \\ \cline{2-5}  & chemical composition & ZrO1.983 \(\pm\) 0.013 & ZrO1.979 \(\pm\) 0.012 & ZrO1.977 \(\pm\) 0.009 & ZrO1.968 \(\pm\) 0.021 \\ \hline \multirow{6}{*}{c-ZrO\({}_{2}\)} & volume \% & 7 & 38.7 & 61 & 73.7 \\ \cline{2-5}  & a = b = c (Å) & 5.142 & 5.109 & 5.107 & 5.113 \\ \cline{2-5}  & \(\alpha=\beta=\gamma\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) & 90\({}^{\circ}\) \\ \cline{2-5}  & lattice volume (Å\({}^{3}\)) & 135.9553233 & 133.35451 & 133.19796 & 133.667979 \\ \cline{2-5}  & chemical composition & ZrO1.998 \(\pm\) 0.003 & ZrO1.995 \(\pm\) 0.017 & ZrO1.991 \(\pm\) 0.008 & ZrO1.983 \(\pm\) 0.016 \\ \hline MnO\({}_{2}\) & volume \% & - & 0 & 0 & 0 \\ \hline \multirow{6}{*}{MnO\({}_{2}\)} & R\({}_{\rm wp}\) & 16.599 & 17.205 & 19.18 & 17.156 \\ \cline{2-5}  & R\({}_{\rm p}\) & 12.902 & 13.28 & 14.79 & 12.973 \\ \hline \multirow{6}{*}{\(\chi^{2}\)} & \(\chi^{2}\) & 1.423 & 1.557 & 1.806 & 1.547 \\ \cline{2-5}  & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \\ \end{tabular}
\end{table} 
Table 3: Rietveld refinement results of 9-CSZ powder after thermal cycle (A400 \({}^{\circ}\)C). Figure 5: HRTEM images of **(a)** CSZ, **(b)** 2 Mn\({}_{-}\)CSZ, **(c)** 3 Mn\({}_{-}\)CSZ, and **(d)** 4 Mn\({}_{-}\)CSZ powder after thermal cycle (\(\triangle\)400 \({}^{\circ}\)C). a and b represent the interplanar spacings. The Vickers hardness values of each specimen before and after thermal shock are shown in Figure 6. The Vickers hardness of 9-CSZ before the thermal shock was 10,674 MPa. In contrast, the Vickers hardness of MnO\({}_{2}\)-doped CSZ substantially increased with doping levels of 2-4 mol% MnO\({}_{2}\), and were 24,662 MPa, 29,437 MPa, and 27,013 MPa, respectively. The highest value was observed in the 3 mol% MnO\({}_{2}\)-doped CSZ, while the 4 mol% MnO\({}_{2}\)-doped CSZ exhibited only a slight decrease. After thermal shock, the Vickers hardness decreased for all specimens, with values of 6247 MPa, 14,305 MPa, 20,294 MPa, and 18,637 MPa, respectively. However, the overall trend remained the same as that observed before thermal shock. Figure 7 shows the specific wear amount of each specimen before and after the thermal shock. The specific wear amount of 9-CSZ before thermal shock was 1.59 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, whereas for 2 to 4 mol% MnO\({}_{2}\)-doped CSZ, it was 0.28 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, 0.17 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, and 0.38 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, respectively. This demonstrates a significant reduction in the wear amount compared with 9-CSZ. After thermal shock, the specific wear amounts were 3.77 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, 0.82 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, 0.42 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, and 0.99 \(\times\) 10\({}^{5}\) mm\({}^{3}\)/Nm, respectively.