General synthesis of magnetic binary transition metal telluride nanocrystals

Abstract

Binary transition metal telluride (MTe_2−x, 0 ≤ x ≤ 1) nanocrystals (NCs) display fascinating structure- and composition-dependent magnetic properties for potential applications in spintronic devices. However, achieving precise control over the morphology and composition of MTe_2−x NCs during synthesis poses significant challenges due to the limited reactivity between the metal and Te as well as the ambiguous reaction mechanisms. Here, we demonstrate a general synthetic approach to produce a diverse range of MTe_2−x NCs, including Cr₂Te₃, MnTe₂, FeTe₂, CoTe_2−x, and NiTe_2−x. Specifically, a series of NiTe_2−x nanosheets were synthesized by manipulating the feed ratio of Te : Ni and reaction temperature. Our results indicate that the formation mechanism of these binary MTe_2−x NCs can be elucidated through the tellurization of preformed metal oxide nanoparticles. The binary MTe_2−x NCs displayed different magnetic behaviors including ferromagnetic FeTe₂ and Cr₂Te₃, paramagnetic CoTe_2−x and NiTe_2−x, and antiferromagnetic MnTe₂. Our work establishes a foundation for the synthesis of magnetic MTe_2−x NCs with precisely tailored morphology and composition and emergent magnetic characteristics.