Electrical conductivity of La_0.8Sr_0.2Co_1–xMn_xO₃ nanoceramics

Abstract

Abstract The Solid Oxide Fuel Cells (SOFCs) are promising sources of clean, environmental friendly energy. The major obstacle in commercialization of such devices is high operating temperature (in the range of 800 °C), which imposes appreciable constraints on the constituent materials. However, the lowering of operating temperature leads to insufficient efficiency of fuel cell, mainly due to the substantial reduction of electrochemical activity of electrode materials. Bringing down the SOFCs’ operating temperature to 600 °C is the motivation for developing of new materials, which satisfy the electrical conductivity and catalytic activity requirements. The most promising group of materials are perovskite‐based oxides. In the present paper, electrical properties of the La 0.8 Sr 0.2 Co 1–x Mn x O 3 ceramics are reported. Samples were in form of pellets prepared from the nanopowders obtained by the Pechini method. Different sintering temperatures of ceramics lead to differences in resulting grain size up to 60 nm, as determined by Scherrer formula. Electrical measurements performed with Keithley 2400 General‐Purpose Source Meter in temperature range of 27–800 °C in air. Two regimes with different activation energies could be distinguished, originated in spin transitions usually observed in perovskite oxides containing transition metals ions. Dependence of these activation energies on the grain size was observed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)