Valence state and ionic conduction in Mn‐doped MgO partially stabilized zirconia |
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| Authors: | Buyoung Kim Heesoo Lee |
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| Affiliation: | Department of Materials Science and Engineering, Pusan National University, Busan, South Korea |
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| Abstract: | 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. |
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| Keywords: | conductivity manganese/manganese compounds phase transformations X‐ray methods zirconia: partially stabilized |
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