Reaction characteristics of La0.84Sr0.16CrO3 formation

We studied the kinetics of La0.84Sr0.16CrO3 formation from a precursor consisting of La and Sr chromium oxides and carbonates made by spray roasting. Pure LaCrO3 becomes cubic at temperatures exceeding 1900 °C. Strontium doping lowers the transition temperature, for example, that of La0.84Sr0.16CrO3 is 1700 °C. This transition is gradual and occurs over a 700 °C range upon heating and cooling. Low temperature (LT) air calcination (450 °C) of the precursor yields a mixture of LaCrO4 and SrCrO4, which following 20 h of heating at 1440 °C produces a homogeneous powder. Secondary electron images of this precursor reveal dense spheres with 95% of the theoretical density of La0.84Sr0.16CrO3. High temperature (HT) calcination (800 °C) yields a mixture of LaCrO3 and SrCrO4, which following 40 h of heating at 1500 °C produces a uniform product. The LT and HT calcination causes oxygen loss.