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 temperatures and oxygen partial pressures. Reduction of doped lanthanum chromite resulted in a linear expansion of the sample that was dependent on the acceptor (Sr, Ca) concentration, temperature, oxygen partial pressure, and oxygen content within the sample. Additional doping with aliovalent B-site additives significantly reduced lattice expansion in reducing environments. The lattice expansion in reducing environments was directly related to the loss of lattice oxygen and the simultaneous reduction of Cr2+ to Cr3+ to maintain electroneutrality.