Cr-based chalcogenide spinels CuCr2S4, CuCr2Se4 and CuCr2Te4 are metallic with TC's of 377, 430 and 360 K, respectively. Because of their high Curie temperatures, these materials are potential candidates for spin-based electronics and other applications. Nanocrystals of the room temperature magnetic spinel CuCr2S4 have been synthesized using a facile solution-based method for the first time. The synthesis involves hot injection of an excess of 1-dodecanethiol (1-DDT) into a boiling coordinating solvent containing CuCl2 and CrCl3.6H2O. The synthesized material is superparamagnetic at room temperature, but exhibits ferromagnetic behavior at low temperatures. We have extended the work to the synthesis of Cu1-xCoxCr2S4 (x = 0-1) nanocrystals over the entire composition range. While CuCr2S4 is a ferromagnetic metal, CuCo2S4 is known to be ferrimagnetic semiconductor. Systematic changes in the lattice parameter, morphology and magnetic properties of the nanocrystals are observed with composition. The nanocrystals are magnetic over the entire range, with a decrease in the magnetic transition temperature with increasing Co content.

Colloidal synthesis and magnetism of chromium-based chalcospinel nanocrystals

245th National Meeting (2013)

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