Nanocrystalline Chalcospinels: Synthesis and Investigation of Magnetocaloric and Thermoelectric Properties
ABSTRACT :
Magnetic nanomaterials have been intensively investigated because of their unique nanosize-dependent properties and broad applicability in different areas including spin-based electronics, recording media, magneto-optics, magnetocaloric refrigeration and biomedical applications. Thus far, the majority of magnetic nanomaterials that have been studied are focused on metals, alloys, and oxides. The synthesis and properties of chalcogenide-based magnetic nanomaterials remain largely unexplored. Chromium (Cr)-based spinel chalcogenides (chalcospinels), ACr2X4 (A=Cu, Cd, Zn and Co; X=S, Se, and Te), have generated renewed interest in recent years since they exhibit a rich variety of physical phenomena including colossal magnetoresistance, giant red-shift of the absorption edge, magnetic field-induced structural transformation, multiferroicity, spin and orbital frustration, unique magneto-transport, magnetodielectric, magnetocaloric and thermoelectric properties due to their exhibition of an enormous range of magnetic exchange strengths, different magnetic ground states and flexible crystal structures. Besides, spinel structure in general is highly adaptable to substitutions. A large combination of divalent and trivalent cations at the tetrahedral and octahedral sites and the close interrelation between structural, magnetic, optical, thermal and transport properties makes chalcospinels an appealing system of choice for investigating the effect of particle size reduction on the fundamental physical properties. Thus, in the first part of the talk bulk, macroscopic properties of selected chalcospinels will be discussed. In the later part, the plans for the immediate future are outlined.