Single-crystal electrolytes grain boundary

Intense research efforts have been devoted to characterize the electronic trap states in single crystal and colloidal Ti02 [173-176], although it is still unclear whether these states originate from defects in the bulk and surface regions, from the grain boundaries of the particles, from Coulomb trapping due to interactions of electrons with the cations of the electrolyte, or from a combination of all these factors. 

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