Electron transport and mobility analysis in La/Sr co-doped CaMnO 3–δ

The specific electric conductivity ( σ ) and Seebeck coefficient ( S ) are measured in electron-doped manganites Ca 1– х – у Sr x La у MnO 3– δ ( х = 0.4 and y = 0–0.1) in air within temperature ( Т ) range 350–1220 K. The new approach is suggested to explain the metallic-like increase of S with T based on combination of a small polaron theory with charge disproportionation and spin direction of manganese cations. The temperature-dependent variations of the charge disproportionation equilibrium constant, concentration, and mobility ( μ ) of charge carriers are derived from the experimental data for S ( T ) and σ ( T ). The obtained mobility values vary within 0.1–0.55 cm 2 V −1 s −1 .