Synthesis of LaCrO₃ and La_0.9Ca_0.1CrO ₃ by modified glycine nitrate process

LaCrO₃ and La_0.9Ca_0.1CrO₃ ceramics were synthesized in the modified glycine nitrate process (MGNP). The effect of the equivalence ratio Φ_e of precursor mixtures on the combustion reaction was investigated by means of DSC and TG-FTIR analyses. It was found that for Φ_e > 0.65 the combustion reaction proceeds in a self-propagating one-step process, resulting in the formation of well-crystallized single-phase powders. Further glycine addition (Φ_e < 0.65) leads to sluggish multi-step combustion, which is typical for fuel-rich combustion, and the formation of secondary phases suchas La₂CrO₆. Further more it could be found that the ignition temperature of the precursors rises with rising fuel content. An influence of the equivalence ratio on the specific surface area and particle size of synthesized powders could not be detected. The specific surface area of the powders was in the range of 5-10 m²/g and particle size 100-150 nm.