Figure shows the phase percentage of the detected cubic, tetragonal, monoclinic phases. The samples sintered at 1000 °𝐶 and 1100 °𝐶 showed a relatively small weight fraction of monoclinic phase which decreased by increase in sintering temperature and didn't appear in other XRD patterns. Samples sintered at 𝑇 > 1200 °𝐶 showed the only two phases of cubic and tetragonal. The weight percentage of the tetragonal decreased by increase in the temperature from 𝑥 H ≈ 80 𝑤𝑡% at 1100 °𝐶 to 𝑥 H ≈ 30 𝑤𝑡%. This phenomenon implied that increase in sintering temperature is beneficial to maintain the highly-conductive cubic and tetragonal phases of 6Sc1CeZr and avoid formation of monoclinic and (less probable) rhombohedral phases. Raman spectra of the sintered samples from 1000 °𝐶 to 1650 °𝐶 with the corresponding phases labeled using square (cubic), circle (tetragonal), and triangle (monoclinic) markers. The 𝑐 ↔ 𝑡 phase transition happens by oxygen ion displacement from fluorite ideal sites (8C sites) . The X-ray atomic scattering of oxygen is fundamentally smaller than that of 𝑍𝑟, 𝐶𝑒 and 𝑆𝑐 to detect tetragonal regions . Therefore, obtaining Raman data is strongly recommended as a complimentary technique indenting to phase analysis of 𝑍𝑟𝑂 ! -based solid solutions. The Raman spectra of investigated areas readily showed the polymorphism of zirconia with the presence of cubic, tetragonal, and monoclinic phases. The tetragonal phase was detected to be the prevailing phase in all samples. Thus, Raman spectra of the investigated samples is in a good agreement with the obtained XRD data. The primary Raman shift peaks of the tetragonal phase occurred at 265, 331, 469, and 640 𝑐𝑚 51 and that of the cubic phase was detected at 640 𝑐𝑚 51 which are in a good agreement with literatures . The monoclinic peaks were detected at 362, 415, 538, and 678 𝑐𝑚 51 which is in a good agreement with literatures . In samples sintered at The obtained Raman modes didn't considerably differentiate in the location and width of the tetragonal peaks by increase in the sintering temperature. However, the primary cubic peak of the first order active Raman mode at 640 𝑐𝑚 51 (𝑇 : = 1000 °𝐶) changed to 642 𝑐𝑚 51 (𝑇 : = indicator peak. The slight decrease in the average bond length of the 𝑍𝑟 6% ⋯ 𝑂 65 should cause the increase in the bond strength and consequently shift the Raman modes toward higher vibrational frequencies. The shift can be also related to a mass effect of the constitutional cations on the vibrational modes in binary and ternary systems. In scandia-ceria-zirconia ternary system, 𝑆𝑐 (44.955 𝑢) is more than three times heavier than 𝐶𝑒 (140.116 𝑢). Therefore, the small shift in the modes should be influenced by small dopant amount of 1𝑚𝑜𝑙% 𝐶𝑒. Doping 𝑍𝑟𝑂 ! with 𝐶𝑒𝑂 ! shifted the Raman bands related to the stretching modes of 𝑍𝑟 -𝑂 (at ~640 𝑐𝑚 51 ) shift toward lower wavenumbers implying that the average cation-oxygen bond distances are lengthened as 𝐶𝑒 &% content increases. However, addition of 𝑆𝑐 ! 𝑂 " shifted the 𝑍𝑟 -𝑂 (at ~640 𝑐𝑚 51 ) to higher wavelengths. Since the 𝑆𝑐 content is higher than 𝐶𝑒, a gradual shift of the main cubic peak to the higher frequencies was observed. Kim et al. observed that the degree of tetragonality of the cell ( 𝑐 𝑎 ⁄ ratio) plays a crucial role in the phase transition in zirconia systems in a way that 𝑍𝑟𝑂 ! solid solution stability increases by a decrease in tetragonality toward unity and vice versa. It has been well-discussed that a significant inductive load effect resulted from the leads and instrument induction always presents in high-frequency data points . The main transport properties of the ionic conductors are represented in the high-frequency regime of the EIS data. Therefore, it is crucial to subtract the inductive load effect from the obtained data to eliminate the instrumentation and leads resistance as Bauerle in his well-known paper discussed in details . This inductance appears as an imaginary part of the impedance data in the positive direction of the imaginary part of the impedance axis (direction), as shown in figure . It is noteworthy that, unlike the samples' behavior, there is not a significant dependence of inductance on temperature. At low temperatures, the effect of the inductance is not effective although it is present, but in high temperatures, the inductance effect is obvious as the highest frequency data points lying below the x-axis. The fitting in this manuscript is restricted to the high-frequency regime of the impedance spectra after subtracting the lead inductance using resistors, capacitors, and constant phase element (CPE). after subtraction of the induction load acquired at 400 °𝐶 and 800 °𝐶, respectively. As can be seen, the inductive load effect at higher temperatures significantly contribute to the sample resistance, contrary to low temperatures. The insets show the fit and R-C circuit used for the fit. As can be seen, the data before subtraction of inductance, need to be fit using a resistor and a CPE element which deviate from an ideal capacitor. However, after removing inductance load, a good fit is achieved just using resistor and capacitor. From the EIS data it was observed that the grain, grain boundary, and total resistivity have analogous behavior. This high electrical conductivity is attributed to the high achieved relative density and most minuscule contribution of grain boundary resistivity to the total resistivity as sintering temperature increased. However, the bulk resistivity is not significantly dependent on grain size and sintering conditions, while two semicircles were observed in the low-temperature regime of the impedance plots. The high-frequency arc corresponds to the grain (bulk) resistance, and the intermediate frequency semicircle corresponds to the grain boundary resistance component. Solid electrolytes such as scandia-ceria-doped zirconia have a negligible electronic conductivity. Although mathematically the electronic conductivity cannot be identically equal to zero, owing to local equilibrium thermodynamic where