The mechanism of the enhancement in the ionic conductivity resulting from cubic phase stabilization in MgO partially stabilized zirconia (MgPSZ) by Mn doping was studied by examining the local Zr-O structure. Cubic phase (14 vol%) in MgPSZ was increased with the addition of MnO₂, and 10 mol% Mn-doped MgPSZ exhibited the highest cubic phase fraction (98.72%), which was analyzed by Rietveld refinement. In addition, only the cubic phase, not the monoclinic and tetragonal phases, was observed in the TEM-SAED pattern of 10 mol% Mn-doped MgPSZ. Doped Mn exhibited a high Mn²⁺/Mn⁴⁺ ratio, which was identified by X-ray photoelectron spectroscopy (XPS). In addition, it indicates that oxygen vacancy formation by substitution of Mn²⁺ in the Zr⁴⁺ site in MgPSZ increased cubic phase fraction. Ionic conductivity of MgPSZ was improved by the cubic phase increase attributed to Mn doping, and 10 mol% Mn-doped MgPSZ exhibited higher ionic conductivity than MgPSZ. To investigate the mechanism of the ionic conductivity improvement, Zr-O local structure in Mn-doped MgPSZ was analyzed by Zr K-edge EXAFS of MgPSZ, and the number of bonding of the Zr-O first shell decreased with increased Mn substitution. Therefore, it was considered that the oxygen vacancy generation led to an increase in the cubic phase and the number of ionic conduction sites.

中文翻译：

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Mn掺杂的MgO部分稳定的氧化锆中的价态和离子传导

通过研究局部Zr-O结构，研究了通过Mn掺杂提高MgO部分稳定的氧化锆（MgPSZ）中立方相的稳定性而导致的离子电导率提高的机理。通过添加MnO _2可以增加MgPSZ中的立方相（14体积％），并且10摩尔％的Mn掺杂的MgPSZ表现出最高的立方相分数（98.72％），这通过Rietveld精炼进行了分析。另外，在10mol％Mn掺杂的MgPSZ的TEM-SAED图中，仅观察到立方相，而不是单斜相和四方相。掺杂的Mn表现出高的Mn ²⁺ / Mn ⁴⁺比率，这通过X射线光电子能谱法（XPS）鉴定。另外，这表明通过Zr中Mn ²⁺的取代形成氧空位MgPSZ中的⁴⁺位点增加了立方相分数。MgPSZ的离子电导率由于Mn掺杂引起的立方相增加而得到改善，并且10 mol％Mn掺杂的MgPSZ的离子电导率比MgPSZ高。为了研究离子电导率改善的机理，通过MgPSZ的Zr K边缘EXAFS分析了Mn掺杂的MgPSZ中的Zr-O局部结构，并且随着Mn取代量的增加，Zr-O第一壳的键合数量减少。因此，认为氧空位的产生导致立方相和离子传导位点数量的增加。