DIMENSIONAL INSTABILITY OF DOPED LANTHANUM CHROMITE

Lattice expansion, phase stability, and dimensional stability of doped lanthanum chromites have been examined over a wide range of temperatu res and oxygen partial pressures. Reduction of doped lanthanum chromit e resulted in a linear expansion of the sample that was dependent on t he acceptor (Sr, Ca) concentration, temperature, oxygen partial pressu re, and oxygen content within the sample. Additional doping with aliov alent B-site additives significantly reduced lattice expansion in redu cing environments. The lattice expansion in reducing environments was directly related to the loss of lattice oxygen and the simultaneous re duction of Cr2+ to Cr3+ to maintain electroneutrality.