Low temperature hydrothermal synthesis, structure and magnetic properties of RECrO3 (RE = La, Pr, Nd, Sm)

Abstract

Perovskite structured rare-earth chromites (RECrO₃) are an interesting family of functional materials due to their wide application in numerous areas. Various methods have been used to synthesize this family of materials; however, such methods usually need a high temperature crystallization process above 800 °C, and only produce polycrystalline ceramics. Herein, a series of RECrO₃ single crystal samples with uniform particle sizes were prepared via a mild hydrothermal method with temperatures as low as 240–260 °C, and the synthesis conditions were studied in detail. Samples of LaCrO₃, PrCrO₃, and NdCrO₃ were indexed to the Pnma space group, whereas SmCrO₃ was indexed to Pbnm. The shapes of the crystals changed from cubic to plate as a result of the crystal lattice distortions induced by the reduction in the size of the A-site rare-earth cation. Raman spectra of the samples showed characteristic vibration modes of CrO₆ clusters. Temperature dependent magnetization studies showed a transition from antiferromagnetism to paramagnetism in all the samples. Higher maximum and residual magnetization was achieved in all the hydrothermally prepared samples compared with those prepared by other methods.