Growth process and magnetic properties of α-FeSe nanostructures

Growth process and magnetic properties of PbO-type α-Fe x Se nanostructures with shape changing from nanocacti to nanopetals and then to nanosheets are investigated. With iron acetylacetonate [Fe(acac) 3 ] and Se powder as raw materials, the diffusion process of Fe atoms dominates the synthesis of α-Fe x Se nanocacti following phase transitions from FeSe 2 to Fe 3 Se 4 and finally to α-Fe x Se. When a mixed solution containing Se precursor and Fe(acac) 3 was used as the raw material, the formation of FeSe 2 and Fe 3 Se 4 can be avoided and, bended α-Fe x Se nanopetals can be prepared at 345 °C, which became flat nanosheets with a [001] preferred orientation as extending the reaction time from 1 to 4 h. No superconducting transition occurs in the α-Fe x Se (0.84 ≤ x ≤ 1.05) nanostructures due to composition heterogeneity or size effect. Magnetic measurements indicate that an antiferromagnetic component with a Néel point at about 45 K dominates the magnetic properties of the α-Fe 0.87 Se nanosheets.