Preparation and characterization of high purity Zn-doped (La_(0.8)Sr_(0.2))AlO_(2.9)) electrolyte for intermediate temperature solid oxide fuel cells

摘要

Ionic conductivity of perovskite oxides La_(0.8)Sr_(0.2))AlO_(2.9) with different size of B-site ions were measured. In addition, the behavior of lattice parameter with dopant content was investigated in terms of the size of the B-site ions and the tolerance factor of the perovskite structure; the ionic conductivity of La_(0.8)Sr_(0.2)Al_(1-x)Zn_xO_(3-δ) (LSAZ) was measured at various operating temperatures, from 500 to 800℃ in air. Ionic conductivity was found to be significantly increased by adding small amount of Zn doping. The La_(0.8)Sr_(0.2)Al_(0.8)Zn_(0.2)O_(2.8) specimen showed ionic conductivities at 0.0304Scm~(-1) at 800℃ in air. The average thermal expansion coefficient (TEC) of La_(0.8)Sr_(0.2)Al_(0.8)Zn_(0.2)O_(2.8) was 10.07 × 10~(-6) K~(-1) in the temperature range from 40 to 800 ℃ in air. As a result, the La_(0.8)Sr_(0.2)Al_(0.8)Zn_(0.2)O_(2.8) is a prospective candidate as electrolyte material for solid oxide fuel cells in intermediate temperatures.