Influence of Ce3+ polarons on grain boundary space-charge in proton conducting Y-doped BaCeO3

Abstract In this work, we report that modification of the chemical composition of grain boundaries of La2/3-xLi3xTiO3 double perovskite, one of the most promising Li-ion conducting solid electrolytes, can be a convenient and versatile way of controlling the space charge potential, leading to a mitigated electrical resistance of the grain boundaries. Two groups of additives are investigated: lithium-enriching agents (Li3BO3, LiF) and 3d metal ions (Co2+, Cu2+), both expected to reduce the Schottky barrier. It is observed that Li-containing additives work effectively at a higher sintering temperature of 1250 °C. Regarding copper, it shows a much stronger positive impact at lower temperature, 1150 °C, while the addition of cobalt is always detrimental. Despite overall complex behavior, it is documented that the decreased space charge potential plays a more important role in the improvement of lithium conduction than the thickness of the grain boundaries. Among the proposed additives, modification of La2/3-xLi3xTiO3 by 2 mol.% Cu2+ results in the space charge potential reduction by 32 mV in relation to the reference sample, and the grain boundary specific conductivity increase by 80%, as measured at 30 °C. Introduced additive allows to obtain a similar effect on the conductivity as elevating the sintering temperature, which can facilitate manufacturing procedure. Graphic abstract

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Isn't the space-charge potential in ceria-based solid electrolytes largely overestimated?

Physical Chemistry Chemical Physics ◽

10.1039/c6cp02177h ◽

2016 ◽

Vol 18 (29) ◽

pp. 19787-19791 ◽

Cited By ~ 12

Author(s):

Sangtae Kim

Keyword(s):

Grain Boundary ◽

Space Charge ◽

Potential Barrier ◽

Solid Solutions ◽

Solid Electrolytes ◽

Ceria Solid Solutions ◽

Space Charge Potential ◽

Charge Potential

The height of the potential barrier at the grain boundary in concentrated ceria solid solutions found in the literature is largely overestimated.

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Dynamics Of Grain Boundary Space-Charge Potential In Electroceramics

Microscopy and Microanalysis ◽

10.1017/s1431927600013829 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 100-101

Author(s):

Kevin D. Johnson ◽

Vinayak P. Dravid

Keyword(s):

Grain Boundary ◽

Electrical Activity ◽

Charge Density Distribution ◽

Complex Interplay ◽

Band Bending ◽

Space Charge Potential ◽

Downward Shift ◽

Charge Potential ◽

Barrier Model ◽

Boundary Space

A large number of bulk and thin-film electroceramic systems contain electrically active interfaces which dictate the various useful electronic properties of these devices. The electrical activity of these interfaces stems from a complex interplay among various interfacial attribute but often involves formation of some form of electrostatic potential at the interfaces which is modified under applied bias of current and/or voltage.Figure la schematically shows charge distribution at a model grain boundary (GB), while Figure 1(b) shows its corresponding potential distribution. As shown in Figure 1(c), the energy band structure bends opposite to this built-in potential, causing a downward shift at the grain boundary . The difficulty with evaluating the Schottky barrier model, which is often invoked to explain GB electrical activity, is that the charge density distribution and therefore the band bending is expected to dynamically alter as bias is applied across the grain boundary. This variation adds another level of complexity to theoretical descriptions of the barrier behavior

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