Combustion synthesis and characterization of Ln1−xMxCr0.9Ni0.1O3 (Ln = La and/or Nd; M = Sr and/or Ca; x ≤ 0.25) perovskites for SOFCs anodes

Abstract

A series of chromite perovskites with the general formula Ln 1−x M x Cr 0.9 Ni 0.1 O 3 (Ln = La and/or Nd; M = Sr and/or Ca; x ≤ 0.25) has been prepared by three combustion synthesis routes using a different combustible substance each time: glycine, urea and sucrose. In order to isolate the effect of divalent dopant concentration from the A cation steric effects, the whole group has a fixed mean A cation radius, < r A > ≈ 1.22 Å, and cation size disorder, σ 2 (r A) ≈ 0.0001 Å 2 , but variable doping x. Their crystal structure, microstructure, electrical properties and expansion coefficients have been investigated on the basis of their possible use as anode materials for intermediate temperature solid oxide fuel cells (SOFC). Cell parameters, grain sizes, expansion coefficients and conductivities all are found to be dependent on x and the combustible substance used. The most interesting relationship is the negative dependence of the conductivity with x under H 2 atmosphere: conductivity decreases with doping which is the opposite to the expected behavior for a p-type doped perovskites and has not been reported before.

Influence of A-Site Modifications on the Electrical and Crystallographic Properties of Ln0.2Sr0.7-XCaxTi0.95Fe0.05O3-δ (Ln=La, Nd) Based Fuel Electrode for Solid Oxide Cell

“…Nowadays Solid Oxide Fuel Cells (SOFCs) are known as an efficient, energy-saving, fuel flexible, and environmentally-friendly power generating device and they can be considered as one of the key components of the future energy concept (1)(2)(3). In particular, one of the most active area is the study of SOFC anodes due to the operation of commercial SOFC devices is strongly dependent on the behavior of this electrode, which is in contact with the fuel and its impurities (4,5). Ni-cermet as typical SOFC hydrogen electrode material displays outstanding catalytic performance in hydrogen, but the main concern for current nickel-cermet anodes is that because of carbon deposition onto surface, they are unable to work efficiently with hydrocarbon fuels at intermediate operating temperature range (600-800 °C).…”

“…Ni-cermet as typical SOFC hydrogen electrode material displays outstanding catalytic performance in hydrogen, but the main concern for current nickel-cermet anodes is that because of carbon deposition onto surface, they are unable to work efficiently with hydrocarbon fuels at intermediate operating temperature range (600-800 °C). Additionally, poor sulfur tolerance and Nicoarsening might cause instability of electrode (5)(6)(7)(8). Therefore, there is a growing interest to explore new materials and replace the Ni-cermet fuel electrodes in order to eliminate mentioned above drawbacks.…”