Growth of a Hexagonal Α-Fe1−xcrxse (x ≥ 0.4) Alloying Phase with Room-Temperature High Coercivity by Cr Introduction

3d transition metal chalcogenides have gradually become candidates for magnetic materials due to their unique d-electronic structures. However, a relatively lower Curie temperature (TC) and coercivity (HC) limit their widespread applications. Here, we report a high-temperature organic-solvent-phase method for the synthesis of hexagonal alpha-Fe1-xCrxSe (0 <= x <= 0.6) alloyed nanosheets with high TC through Cr introduction. Without Cr introduction, FeSe nanosheets appear as a mixture of tetragonal beta-FeSe and hexagonal alpha-FeSe phases with a soft/hard decoupled hysteresis loop of HC similar to 3.35 kOe at 5 K. With an increase in the Cr content, alpha-Fe1-xCrxSe gradually becomes dominant. The tetragonal-to-hexagonal phase transition is completed at the optimum doping of Cr (x = 0.4), and alpha-Fe1-xCrxSe exhibits hard magnetic behavior. The coercivity (HC) can be as high as 15.80 kOe at 5 K and 4.98 kOe at 300 K when the Cr concentration reaches 60%. The synthesis of alpha-Fe1-xCrxSe alloy provides a potential material for hard magnets. Therefore, the doping-induced phase transition is an effective way to synthesize ideal phase nanomaterials.(c) 2022 Elsevier B.V. All rights reserved.