Illustration from Scientific Research

Simplified schematic illustration of the redox response of the STNNi host lattice and its impact on the diffusion of charged dopants (such as NiTi) to the surface. Negatively charged Sr vacancies are formed under oxidizing conditions, which are kinetically trapped in the near-surface region, and hence a negative space charge potential is established. A positive space charge potential may be formed under highly reducing conditions by the generation of oxygen vacancies energetically trapped in the near-surface region. Kroger–Vink notation is used in the sketch; e –, electron. In SrO sp , sp is the surface phase.

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