Controllable synthesis and magnetic property of BiMn2O5 crystals

Uniform submicron BiMn2O5 particles were prepared via a facile one-step hydrothermal route at low temperature. Bi(NO3)3, MnCl2·4H2O and KMnO4 were used as starting materials; KOH as a pH adjustor and also as a mineralizer. Single-crystalline orthorhombic BiMn2O5 sample with controllable morphology was obtained. The microstructure strongly depends on the molar ratio of the starting materials, KOH concentration and reaction temperature. X-ray photoelectron spectroscopy shows the existence of Mn4+ state. Magnetic measurement indicates Néel temperature TN at 44 K. The susceptibility above TN obeys the Curie–Weiss law, χ = C/(T − θ), with θ = −350 K. The effective paramagnetic moment μeff = 4.66 μB/Mn, demonstrating the coexistence of mixed Mn3+ and Mn4+ valences.