Electrical properties of perovskite-type La(Cr1-xMnx)O3+δ

Perovskite-type La(Cr1-xMnx)O3+delta (0.0 less than or equal to x less than or equal to 1.0) was synthesized using a sol-gel process. The crystal structure of La(Cr1-xMnx)O3+delta changes from orthorhombic to rhombohedral at x = 0.6. The Mn4+ ion content increases monotonically in the range 0.2 less than or equal to x less than or equal to 1.0. The magnetic measurement of La(Cr1-xMnx)O3+delta indicates that a Mn3+ ion is a high-spin state with (d epsilon)(3)(d gamma)(1). The variation of the average (Cr, Mn)-O distance is explained by ionic radii of the Cr3+, the Mn3+, the Mn4+ ions. Since the log sigma T-1/T curve is linear and the Seebeck coefficient (alpha) is independent of temperature, it is considered that La(Cr1-xMnx)O3+delta is a p-type semiconductor and exhibits the hopping conductivity. (C) 1999 Elsevier Science B.V. All rights reserved.