General synthesis of magnetic binary transition metal telluride nanocrystals

Binary transition metal telluride (MTe2−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 MTe2−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 MTe2−x NCs, including Cr2Te3, MnTe2, FeTe2, CoTe2−x, and NiTe2−x. Specifically, a series of NiTe2−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 MTe2−x NCs can be elucidated through the tellurization of preformed metal oxide nanoparticles. The binary MTe2−x NCs displayed different magnetic behaviors including ferromagnetic FeTe2 and Cr2Te3, paramagnetic CoTe2−x and NiTe2−x, and antiferromagnetic MnTe2. Our work establishes a foundation for the synthesis of magnetic MTe2−x NCs with precisely tailored morphology and composition and emergent magnetic characteristics.