Direct evidence of dopant segregation in Gd-doped ceria

Abstract

Microstructures and segregations of dopants and associated oxygen vacancies in gadolinium-doped ceria (GDC) have been characterized by high-resolution transmission electron microscopy (HRTEM) and scanning TEM (STEM). Diffuse scattering was detected in 25 at. % GDC (25GDC) in comparison to 10GDC, which is ascribed to nanodomain formation in 25GDC. HRTEM, dark-field, and STEM Z-contrast imaging investigations all provide direct evidence for dopant segregation in doped ceria. It is illustrated that dopant cations cannot only segregate in grain interior forming larger nanodomains but also at grain boundary forming smaller ones. Detailed analyses about nanodomain formation and related dopant segregation behaviors are then elucidated.

The diffusions and associated interfacial layer formation between thin film electrolyte and cermet anode in IT-SOFC

“…The homogeneous 20GDC nanopowder was synthesized by ammonium carbonate coprecipitation method [21] and used as starting powders. NiO, 20GDC, and acetylene black were milled by zirconia balls in ethanol for successive 12 h with a rotation rate of 2 r/s.…”

Incubational domain characterization in lightly doped ceria

“…Also, the segregation of dopant to surfaces, interfaces and grain boundaries has been verified as playing an important role that can strongly affect the ionic conductivity of doped ceria [11]. Recently, the domain model has been described to elucidate this non-monotonic phenomenon that occurs in conductivity evolution as a function of dopant concentration [12][13][14][15]. It has been illustrated that the aggregation/segregation of dopants and accompanied charge-compensating oxygen vacancies will induce the formation of nanometersized (or nano-sized) domains in doped ceria with short-range ordered structures.…”

An Interdisciplinary View of Interfaces: Perspectives Regarding Emergent Phase Formation

“…High resolution scanning transmission electron microscopy has revealed evidence of Gd segregation in both the bulk as nanodomains as well as at the grain boundaries [27][28][29][30]. Figure 3 graphically illustrates the aggregation of M þ3 dopants substituted on M þ4 sites at the grain boundary resulting in decreased oxygen vacancy concentration at the interface.…”