Synthesis and characterization of polycrystalline fe_1.025se prepared using mechanical alloying followed by powder in a sealed tube method

In this work, preparation of Fe1.025Se samples was done using a solid-state reaction. Iron and selenium powder were used as raw materials. The raw materials were milled using a shaker mill for 5 hours after weighed in an atomic ratio of Fe:Se=1.025:1. To find out the formation of polycrystalline Fe1.025Se, the milled powder was then compacted in a stainless-steel tube and sintered at a temperature of 355°C (for sample 1) and 745°C (for sample 2) for 6 hours. All samples were sintered in the air atmosphere and cooled rapidly in the air. XRD was used to analyze the phase formation. Based on the diffraction pattern calculation, the sintered sample at a temperature of 745°C has a higher mass fraction of the tetragonal phase than the sample sintered at 355°C. The lattice parameters of the sample sintered at a temperature of 745°C are a = 3.7688 Å and c = 5.5236 Å. According to the resistivity measurement results, it appears that the sample sintered at 745°C has a critical temperature onset of ~13.28 K.