Premium
Valence state and ionic conduction in Mn‐doped MgO partially stabilized zirconia
Author(s) -
Kim Buyoung,
Lee Heesoo
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15333
Subject(s) - ionic conductivity , tetragonal crystal system , materials science , rietveld refinement , x ray photoelectron spectroscopy , monoclinic crystal system , ionic bonding , doping , analytical chemistry (journal) , valence (chemistry) , cubic zirconia , crystallography , phase (matter) , crystal structure , ion , chemistry , ceramic , nuclear magnetic resonance , metallurgy , physics , optoelectronics , organic chemistry , electrode , chromatography , electrolyte
The mechanism of the enhancement in the ionic conductivity resulting from cubic phase stabilization in MgO partially stabilized zirconia (Mg PSZ ) by Mn doping was studied by examining the local Zr‐O structure. Cubic phase (14 vol%) in Mg PSZ was increased with the addition of MnO 2 , and 10 mol% Mn‐doped Mg PSZ 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 Mg PSZ . Doped Mn exhibited a high Mn 2+ /Mn 4+ ratio, which was identified by X‐ray photoelectron spectroscopy ( XPS ). In addition, it indicates that oxygen vacancy formation by substitution of Mn 2+ in the Zr 4+ site in Mg PSZ increased cubic phase fraction. Ionic conductivity of Mg PSZ was improved by the cubic phase increase attributed to Mn doping, and 10 mol% Mn‐doped Mg PSZ exhibited higher ionic conductivity than Mg PSZ . To investigate the mechanism of the ionic conductivity improvement, Zr‐O local structure in Mn‐doped Mg PSZ was analyzed by Zr K ‐edge EXAFS of Mg PSZ , 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.