Novel Strategy toward Chromium-Based Thiospinel Multifunctional Magnetic Materials from Amorphous Chromites

Magnetic nanomaterials have a broad range of promising applications in mechanical, electronic, optical, magnetic, chemical, and biological fields due to their excellent physicochemical properties, especially their unique magnetic properties. Chromium-based chalcospinels exhibit a variety of magnetic and electrical properties and attract widespread attention. Although the physical properties of Cr-based chalcospinels have been extensively studied, the fabrication of their micro/nanostructures has always been a challenge. In the present work, we develop a novel method for the preparation of Cr-based chalcospinels. The representative ferrimagnetic semiconductor CoCr2S4, ferromagnetic metal CuCr2S4, and ferromagnetic semiconductor CdCr2S4 are successfully synthesized by direct sulfurization in a solvothermal system using amorphous metal chromites as the precursors. The phase structure, chemical composition, crystal morphology, optical absorption, and magnetic properties of the obtained samples are analyzed comprehensively. The experimental results demonstrate that the prepared CoCr2S4 and CdCr2S4 samples have direct band gaps of 1.71 and 2.49 eV, and their Curie temperatures are about 206 and 90 K, respectively, while the Curie temperature of the CuCr2S4 sample is higher than room temperature. More importantly, the as-established synthesis methodology is expected to be further extended to other Cr-based chalcospinels, thus opening a new avenue for the potentially universal preparation of this material system.