Hydrothermal synthesis and characterization of LaCrO3

Abstract

The synthesis of perovskite-type LaCrO₃ under mild hydrothermal conditions is reported. The synthesized product was characterized by means of XRD, IR, SEM and elemental analysis. The results indicated that the phase corresponded to orthorhombic perovskite-type LaCrO₃, and the product had a narrow particle size distribution in the range of 1–3 µm. The effect of hydrothermal conditions on the synthesis of LaCrO₃ was investigated. Under the hydrothermal conditions used, the optimum crystallization temperature was 240–260 °C. For the formation of pure LaCrO₃, a higher alkalinity (≥ 8 mol dm^–3 KOH) is necessary because Cr³⁺ is significantly amphoteric. In the reactant mixing process, the optimum stirring time is 5–10 min because of the oxidation of CrO₂^– ion by oxygen in the air. CrO₄^2– does not show significant hydrothermal reactivity under the present conditions.