Evidence for a crossover from multiple trapping to percolation in the high-temperature electrical conductivity of Mn-doped LaCrO_{3}

We explain the deep electrical conductivity minimum near x=0.05 in the perovskite-type ceramic ${\mathrm{LaCr}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$ ${\mathrm{O}}_3$ as a crossover between two different regimes of hopping conduction. At low Mn concentrations the diffusion of small polarons among Cr ions is limited by multiple trapping at energetically lower Mn sites. At higher concentrations a percolating path of Mn sites forms and direct transport between Mn ions dominates the conduction process.