A variety of strontium-droped lanthanide chromite compositions were synthesized from a mixed lanthanide (Ln) precursor predominanty consisting of La, Nd, Ce, and Pr. /samples were initially analyzed to assess their sintering characteristics. The most promising sintering behavior was observed for samples of the general formula Ln0.85Sr0.15Cr1-zMzO3 were M = transition metal elements Co, Cu, Ni and V, and 0.0290% theoretical density was attained at 1450C. High density samples were subsequently analyzed with respect to phase stability, thermal expansion, electrical conductivity in air and reducing atmospheres and dilation at low oxygen partial pressures. Virtually all samples indicated an orthorhombic to rhombohedral phase transformation between 750-850C, and non-linear arrhenius electrical conductivity behavior with a positive inflection around 650C indicative of increased carrier concentrations. Both phenmena are related to the influence of the additional A-site cations (in particular Ce in the case of increased conductivity at elevated temperatures). Ln0.85Sr0.15Cr0.95Cu0.05O3 was the only sample that exhibited linear conductivity behavior and no discernible structure transformation, believed to be related to the precipitation of a Ce0.5Nd0.5O1.75 second phase.
Revised: May 3, 2001 |
Published: April 1, 2001
Citation
Simner S.P., J.S. Hardy, and J.W. Stevenson. 2001.Sintering and Properties of Mixed Lanthanide Chromites.Journal of the Electrochemical Society 148, no. 4:A351-A360.PNNL-SA-33801.