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Fermi level pinning in Co‐doped BaTiO 3 : Part II. Defect chemistry models
Author(s) -
Bowes Preston C.,
Ryu Gyung Hyun,
Baker Jonathon N.,
Dickey Elizabeth C.,
Irving Douglas L.
Publication year - 2021
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.17938
Subject(s) - dopant , doping , barium titanate , electrical resistivity and conductivity , stoichiometry , barium , materials science , fermi level , degradation (telecommunications) , condensed matter physics , analytical chemistry (journal) , chemistry , ceramic , physics , composite material , metallurgy , computer science , optoelectronics , telecommunications , quantum mechanics , electron , chromatography
Abstract A first‐principles informed grand canonical defect chemistry model capable of accounting for non‐stoichiometry and partial equilibration of different sub‐lattices is developed and used to study Mg and Mn doped, and (Mg+Y) and (Mn+Y) co‐doped BaTiO 3 to elucidate the role of Mn and Y in improving the resistivity and resistance degradation of BaTiO 3 as observed by Ryu et al. in Part I of this series of papers. The model qualitatively captures the behavior of the samples in all conditions, reproducing the observed carrier plateau and increased resistivity of (Mn+Y) co‐doped BaTiO 3 , and expected trends in the concentrations of free oxygen vacancies with doping. These trends reflect the observed differences in degradation characteristics, and help explain the substantially improved degradation resistance of the (Mn+Y) co‐doped samples. Our model adds to the mechanism proposed by Yeoh et al. that the Fermi level is pinned by the multivalent character of Mn Ti in (Mn+Y) co‐doped BaTiO 3 by giving insight into the role of barium vacancies, the site preferences of the dopants, and defect complexes in this mechanism. These insights provide a set of criteria in the search for sets of co‐dopants with similar behaviors.